The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

THE WORKS Of the HONOURABLE ROBERT BOYLE, Esq EPITOMIZED. (Book 2)

BOOK II. (Book 2)

CHAP. I. Of the Systematical, or Cosmical Qualities of Things.

* 1.1CONSIDERING that the Particu∣lar Qualities of Bodies, depend on a certain Relation, which they have one towards another, by which they are adapted to Act or to be Acted on; I the ra∣ther chuse to call the Qualities consider'd in this Chapter, Systematical or Cosmical Qualities; they not being the Effects of those primary Af∣fections of Bodies consider'd barely as such, viz.

Motion, Size and Shape; but of Bodies so di∣versify'd by those primary Affections, Acting mutually on one another: As Quicksilver is en∣dew'd with a Power to dissolve both Silver and Gold, and an Aptitude to be dissolv'd in Aqua fortis. So that I would not be understood to mean, by Cosmical Qualities, such as may be at∣tributed to the mutual Actions and Passions of Bodies, plac'd in some imaginary Spaces beyond the World, but plac'd in the Universe, as now Constituted, with a vast Variety of Bodies about them.

This I have already hinted in the foregoing Chapters of Forms and Qualities; and there∣fore my design in this Chapter, is, to consider what Qualities a Body may Aquire, by the Im∣pressions or Influence of Agents whose Effects are unknown, or not taken notice of.

And though all these Phaenomena, which are usually attributed to the Laws of Nature, might properly be considered, in a Chapter that bears this Title; yet since those Agents most concern∣ed in the Effecting of these Phaenomena are either the Stars, the subterraneal Parts, or the Aether and Atmosphaere we live in; I shall wave those, and only here consider, what is requisite to prove, that there are such real Qualities, depending on unheeded Agents, and the Ordinary Course of Nature;* 1.2 but before I proceed, I shall briefly in∣timate, that our Notion of Cosmical Qualities is grounded upon these three Propositions.

• 1. That some Bodies are altogether inactive, till they are acted on; and that others, are put into Action, chiefly by the Influence of these Ca∣tholick and unheeded Agents.

• 2. That there are several Bodies, which when put into Action, are subtle enough to insinuate themselves into the Pores of other Bodies, which they are by the Established Laws of Nature for∣ced to act on.
• 3. That an Alteration of the Mechanical Tex∣ture of the Body, is enough to dispose it, or ren∣der it unapt to be worked on, by those unheeded Agents. And these three Propositions I shall en∣deavour to make out by the following Phaenomena and Experiments.

To begin then with the first Proposition, viz. That some Bodies are altogether inactive, till they are acted on; and that others are put into Action,* 1.3 chiefly by the Influence of these Catholick and Ʋnheed∣ed Agents.

The first Part of this Proposition, I presume undeniable, if we consider, That till a Hammer, or some other Body be struck upon a Wedge, it wants the Power or Faculty of cleaving Wood, but when forced by the Impulse of that Body, which strikes upon it, the Wedge presently in∣sinuates it self betwixt the Parts of that Solid, and divides them; As also, that a Knife is alto∣gether unable to attract a Needle, till it hath re∣ceived that Power from a Loadstone.

But to proceed to the second Part of the Pro∣position; I shall, to what I have elsewhere ob∣served (viz. That the Property of a Burning-Glass, in respect of it's Effects, does not proceed from the Convex Figure, considered as such, but the Rays of the Sun cast into a Point) add the fol∣lowing

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Instances. The first is, That a Bar of I∣ron, by standing a considerable time in a Win∣dow, in a perpendicular Line, will acquire a considerable degree of Magnetism, by the In∣fluence of Invisible Agents; and several Mag∣netical Qualities which it had not before. Second∣ly, That tho' a flat Piece of Marble, considered barely as such, hath not a Power to raise any Body by a bare Contact; yet if it be applyed to another, whose Superficies is adapted to it; by virtue of the Constitution and Fabrick of the World, and the concurrent Causes of Bodies a∣bout it, it may acquire such a Faculty, the lower Stone being boyed up by the Weight and Pressure of the ambient Air; yet, if these two Stones were contained in a Vacuum, they would not have such a Power to lift up one another. But to pro∣ceed to

* 1.4The second Proposition; which is, That there are several Bodies, which, when put into Action, are subtle enough, to insinuate themselves into the Pores of other Bodies, which they are, by the Established Laws of Nature, forced to Act on. And here, though some of the Experiments to be related, might be also alledged in favour of that Aether or Mate∣ria coelestis, which some Philosophers have sup∣posed to be dispersed throughout the World; yet the Invisible Agents, which are here to be mentioned, are only such as the Magnetical Ef∣fluvia of the Earth, and also the Air, in reference to it's Spring and Weight.

And first, Tho a Bar of Silver, and another of Steel, be exposed to cool, when red hot, with their ends directly North and South; yet the Textures of these two Metals being different one

from another, the Pores of the Steel, being ope∣ned, and the Metal made plyable, it is by the In∣sinuation of Terrestrial Effluvia, endued with se∣veral Magnetical Qualities; and particularly, when poised, to point North and South; where∣as Silver acquires no such Properties. And that it may be less strange, that the Earth should af∣ford Magnetical Effluvia, which are imagined by some to be very spirituous Ones, I shall add, that having heated an Oblong Loadstone, and expo∣sed it to the Air to cool, with it's Ends pointing North and South, and so deprived it of it's Mag∣netical Qualities; I could make either End to tend to the Southern or Northern Pole, as, upon Ignition, I suffered it to cool with one end dire∣cted either North or Southwards.

To this it may be added, That if the Air be exhausted in some measure out of a Vial with an oblong Neck, and, upon it's Immersion in Water, ones Finger, which prevented the retroadmission of the Air, be presently taken away; the Wa∣ter will contrary to the Tendency of it's own Gravity, presently fly up in the Bottle, being squeezed in by the External Pressure of the Air, lying upon the Surface of the Water, the Spring of the Internal Air, being so weakned, as not to be able to oppose the force of it; whereas in a Vacuo the Water would not be so raised, having no external Agent to boye it up.

* 1.5Again, being desirous to know the Causes of Germination, and from what Causes, that pow∣erful Intumescence of Seeds, when sown, proceed∣ed, I filled several Vessels of Glass, as well as Earth, with common Beans, filling up the Inter∣vals with Water, and tying the Corks fast with

Strings; which being done, when the Beans had imbibed Water enough, their Intumescence was so powerful, as not only to break several of the Vessels, but a great many of the Strings which hindred the raising of the Corks. But that I might be more exact in estimating the Power of that Expansive Force, I put a sufficient Quantity of Beans and Water into a Brass Cylinder, whose Diameter was two Inches, and it's Length six; which being done, and the Orifice of the Cylin∣der being likewise fitted exactly with a Plug, a Trencher was placed upon it, which was broad enough to bear a half hundred weight of Lead: In which Experiment it was to be observed, that in two or three days, the Expansive Force of the Beans had raised the Plug a considerable Height. And it may further be noted in such Tryals, that as the Diameter of the Cylinder is larger, so the Expansive Force of the Beans are able to raise a more considerable Weight.

How far these Experiments may confirm the Corpuscularian Philosophy, or whether that Force may be Mechanically explained by it, I shall leave the Reader to consider, and shall here only observe, That the Air, together with the Aether, may in a great Measure concur to the producing of some of the Phaenomena of Nature, which we imagin it very little concerned in; for besides the Effects which may be ascribed to the Pressure of the Air, it contributes to the producing of some upon another Account; it being easy to be observed, that Flesh may be preserved lon∣ger from Putrefaction, by being secluded from the Contact and Influence of the Air; and also, that the Light which flows from rotten Woods,

and some putrefyed Fishes, will appear and dis∣appear upon the Contact or Separation of ambi∣ent Air.

* 1.6But for a further Proof, that the Air may ef∣fect several things, besides what it produces by virtue of it's weight by the Insensible Motions of it's Parts; I might add, that whereas a Piece of Paper being wet with Oyl, hath it's Pores so al∣tered, as to be capable of transmitting more ea∣sily the Rays of Light; and the Air being impelled, by the Laws of Nature, presently acts upon it, and represents a great many Objects, by being reflected from those Bodies beyond it, which could not appear through it before.

And if a large Box be so contrived, as to have one end of it open, and a Hole in the other end, covered with a Lenticular Glass; if the open end be made up with a fine sheet of Paper, and a small Hole be likewise made upon the Top of the Box; by placing ones Eye to the Lenticular Glass, one may discern upon the Paper the Lively Repre∣sentations of External Objects, and their vari∣ous Motions as well as Shape and Colours; which Phaenomena could by no means be exhibi∣ted, were not either some Insensible Corpuscles, transmitted in the Form of Effluvia from those Objects, or some other subtle Particles of Matter, directed by Local Motion from the Object to the Paper, and from thence to the Eyes.

* 1.7From whence it appears, that the Established Laws of the Universe, in a great measure, con∣tribute to the producing of several Phaenomena, which arise from the Operations of insensible and unheeded Causes: For a further Confirmation of which I shall add, That if a Bar of Iron be held

in a perpendicular Line; so that the lower end of it touch the Northren Point of a Magnetical Needle, it will presently drive it away; where∣as, if the Position of that Iron Bar be so altered, as to touch that Point with the other end, it will, by a contrary Faculty, attract it, except the Iron Bar hath stood a considerable time in a Perpendi∣cular Posture, exposed to the Air and the Magne∣tical Effluvia of the Earth, or hath lain a consi∣derable time, pointing North and South, and so hath acquired a more durable Verticity. And if it should be asked;* 1.8 why, by such Postures, the Magnetical Qualities of Iron should be so much increased? it might probably be answered, that it proceeded from hence, viz. Because the Pores of the Iron, by lying nearer the Magnetical Efflu∣via of the Earth, have their Pores rendred more apt to receive and transmit the Effluvia of the Needle; so that consequently, that Part of the Iron which is most affected by those Steams, must become the stronger, and consequently the North Point of the Needle; for which reason, it must drive away the North Point of the Needle, and attract the South. But if on the contrary, the o∣ther end of the Bar be applyed to the Needle, by a contrary reason, it being less Magnetical, it must attract it. But not to insist upon this Explanation of the Magnetical Qualities of a Bar of Iron, I shall only observe, that it is necessary in order to acquire a durable Magnetical Virtue, that the Iron should stand long in that Perpendicular Po∣sture, which is sufficient to prove what I contend for, viz. That the established Laws of Nature are requisite for the Production of several Phaeno∣mena, which would not be effected, were not those Laws observ'd.

* 1.9But to proceed to the third and last Propo∣sition, viz. That an Alteration of the Mechanical Texture of a Body is enough to dispose it or render it unapt to be work'd on by those unheeded Agents. This is evident from what is practis'd at Sea, it being the usual Custom for the Sea-men, to throw Water upon their Sails to quicken the Motion of their Vessels, when pursu'd by Pi∣rates; for the Threeds of the Sails being swel∣led with Water, and the Pores by that Means made less, the Wind, not finding so free a Pas∣sage through them, must consequently have the greater Force upon the Sail-Clothes, and so drive the Ship forwards more swiftly. Another In∣stance of considerable Effects succeeding a very slight Alteration in Texture may be observed, when, on a windy day, a Chamber-Window is left open; for the Wind, which before only shook the Glass, will presently blow the Curtains about and other things in the Chamber, which are in a Disposition to be easily moved, as Dust, Papers, &c.

But to proceed to Examples altogether not so gross, we may take notice, That though com∣mon Tartar will neither dissolve in the Air, nor easily in Water, yet when Part of it is dri∣ven away by Calcination, it readily dissolves and runs per Deliquium in a moist Air. To which may be added, that tho' a Loadstone by being heated in the Fire and cool'd again, underwent no visible Change as to Shape or Size, nor for as much as could be perceiv'd by the Eye, lost none of it's Parts; yet, by an invisible Change of Tex∣ture, effected by the Magnetical Effluvia of the Earth, it may alter its Verticity according to

the different Postures it is permitted to cool in: And the like Change I have observed in Iron, whose Verticity was altered by a Change of Tex∣ture, wrought by so weak an Agent as the Earth.

To these we may add several Instances in li∣quid Bodies; and first, That, tho' Honey and Water mix'd together in an undue Proportion, reserve each their distinct Natures; yet if four or five Parts of Water be added to one Part of Honey, by some subtle Agents or other, they are presently fermented, and unite into one common Mass; and I am assur'd, by a Mer∣chant who liv'd several Years in the Canary Islands, That if a Hogshead of Wine close stop'd be violently roll'd along; the Texture of the Liquor would be so chang'd, that, if it were but about a Month old, one of the Ends would be burst out, and the Liquor lost. Ano∣ther Instance in which the Texture of the Body disposes it to be so powerfully work'd upon, we have in Glass, which upon a sudden Removal from the Fire into cold Water, is subject to fly in Pieces.

But an Instance which is more remarkable is, That a hot Plate of Copper being permitted to cool upon some which were more moderately hot in the Fire, and thence remov'd upon a Plate; several Pieces like Scales would fly off it, when expos'd to the Atmosphere; and

To conclude this Chapter, I shall add, That the Bolonian Stone acquires such an admirable Quality by Calcination, that, by being plac'd in the Sun-beams for some time, it gets such a Degree of Luminousness, as to retain it a

considerable time, when remov'd into the dark.

CHAP. II. Of Cosmical Suspicions.

THE World about us being stock'd with such a Variety of Objects, and other things, too small or subtle to be discern'd; it may not be unuseful, upon some Accounts, to propose Conjectures, where the Subject con∣sider'd admits of no clearer Discoveries.

* 1.10And First, it is not without Reason I suspect, that, besides those uniform Parts of Matter, of which the Aether, by some Philosophers, is thought to consist, there are also several other Parts of Matter, which are differently dispos'd to work upon Bodies, according to the various Textures of those Bodies they chance to work upon; or according to the different Agents they chance to work concurrently with: And this Suspicion is not improbable, since the inquisitive Gilbert hath not only discover'd the Magnetical Qualities of the Earth to be diffus'd on every side, but also it is commonly known that upon the Hunting of a Deer, several subtle Effluvia are left behind in the Air; which we should pass by unobserv'd, were there not such Creatures as Blood-hounds, endow'd with Organs fitted to receive those subtle Steams.

* 1.11And it is not a little strange, that several Persons should have such peculiar Temperaments,

as to be able to discover Pestilential Steams in the Air, for a considerable time before they are dispos'd to affect other Men; and that those Constitutions should be so dispos'd to be work'd upon by Effluvia, by others not in the least discern'd. And that there are such Bodies, as well as unheeded Effluvia, may be evinc'd by several Instances; as one which was remarkable in the Year 1665, in which, a certain Man, three Months before the beginning of the Plague, was taken with a Swelling in his Groin; which he had likewise as a Forerunner to seve∣ral other Plagues. And Fabritius Hildanus re∣lates a Story no less remarkable of himself; who, when, in his Youth, he had had the Plague, could never pass any House infected with it without a sensible Pain in that Part. To which may be added, a third Instance from that Curi∣ous Physician, who observ'd the various Phaeno∣mena of Distempers at the Siege of Breda, and says, Annotandum hic meritò Naturae Facultatem ad Pestis Praeservationem Momenti esse maximi: Observavi in meipso contaminatos invisente statim inguina olere vel axillas; afficiebatur aliquando Caput, noctu inde Sudor, & secessus tres quatuorve; hoc & aliis accidit, qui fideliter mihi retulerunt. And these Testimonies I am rather inclin'd to depend on, because deliver'd by Men of Judg∣ment and Credit.

Another Suspicion which I am about to re∣late,* 1.12 is, That the Laws of Nature, which con∣tribute to the producing of several Phaenomena, are not only of larger Extent than what we are us'd to imagin; but likewise concur to the Pro∣duction of a greater Variety of Effects: For not

to spend much time in observing, That several Industrious Astrologers and Geographers, have, instead of Physical, given us Mathematical Hy∣potheses; having taken pains to describe the Situations and Motions of the fixed Stars and Planets; and likewise, that they have been Industrious in discovering the four little Pla∣nets, which move about Jupiter; as also the little Moon, which runs about Saturn, as well as several Phaenomena relating to Comets, with∣out considering the Frame and Constitution of those Bodies, which compose our Globe; I con∣ceive it not impossible to make it out, That there is a Commerce betwixt them and our Globe; as well as several Laws or Customs of Nature even in our own Globe not taken notice of by Scholastical and Mathematical Writers.

* 1.13And I am, not without Reason, induc'd to suspect, That this Globe of ours hath undergone several considerable Changes, not only in seve∣ral Countries, but the internal Parts of it; That which is call'd the Mariners Compass, having been, in several Places, observ'd to vary consi∣derably, in its Declension from the true North Pole; as for Instance, about London in the Year 1580 it declin'd eleven Degrees; in 1612 about six; and in the Year 1633 about four Degrees. And I have my self, at one time, observ'd little or no Declension, whereas at another I observ'd it to decline near half a Degree. And I am in∣form'd by one who often observ'd the Variation of the Compass at the Cape of good Hope, that, when he was a young Man, he observ'd it to decline two Degrees Westward; whereas of late, he found the Variation to be six Degrees

and about forty eight Minutes; so that, by his Observation, it had vary'd little less than five Degrees, in the times he hath sayl'd past that Place. From whence we may have Reason to think, That there are certain Agents very pow∣erful, tho' not to be taken notice of, which may work several, and very considerable Changes, even in the Terrestrial Globe it self; which whether regulated by any certain Laws of Na∣ture, we know not.

And besides these, there are several other unheeded Phaenomena, which we have troubled our selves very little to consider about; as the different Weight of our Atmosphere, and the Causes of that Difference; we having only no∣ted that they proceed from some subterraneal Effluviums mix'd with the Air; but what other Effects those Effluviums may have upon other Bodies hath been scarce discover'd.

* 1.14And it is not a little strange, what Monsieur de Rochfort relates, concerning those Hurricanes observ'd in the American Islands; for, whereas, for a long time, they were observ'd to come but once in seven Years; yet in a short time they grew so frequent, as to return two or three times in the same Year. And I have been in∣form'd by an Ingenious Gentleman, that, having liv'd in New England, he observ'd a considera∣ble Alteration in the Temper of that Climate; it being much less cold and more temperate than formerly. And Mr. W. Wood, in his Pros∣pect of New England, takes notice of no incon∣siderable Alteration; who says, That since the English Inhabitants settl'd there, the Showers

of Rain are much more moderate, though more frequent.

* 1.15And the Learned Magnenus observes, in his Tract de Manna, That about three hundred Years ago there was no Manna to be found in Cenotria; and it is not above two Ages since Manna hath been found in Calabria, a Country so famous for it. And the Ingenious French Writer in his History des Isles Antilles Lib. 4. Cap. 6. says, That if the Juice of a Fruit call'd Acajou, falls upon a Cloth, it presently stains it red, which continues till the Tree bears Flow∣ers again; which Phaenomenon will be the more to our Purpose, if it may be doubted, whether it proceeded from the Temper of the Air or Length of Time.

* 1.16But besides these Phaenomena, when I observe the exact time, that the ebbing and flowing of the Sea keeps; and how exactly coincident with the New and Full Moon Spring-Tides happen; as also what vast Spring-Tides are constantly observ'd every Equinox; together with those various Phaenomena, which may be observ'd in Sea-Water, which, in some Places and upon the blowing of some Winds, appears to be luminous, whereas other Parts are, at the same time, neither luminous, nor in the least affe∣cted, so as to become luminous by those Winds at any other time; I am very apt to believe, That these Phaenomena proceeded from some Cosmical Law of Nature; or that the Plane∣tary Vortex was not a little concern'd in pro∣ducing these Effects.

* 1.17And I am not unapt to believe, but that all those Distempers, which are either Endemic or Epidemic, proceed from a certain Influence, which those Globes which move about us, may have, together with some Terrestrial Effluvia, which are different in several Countries.

But not to engage in so fertile a Discourse as the Phaenomena, which every particular Region affords; I shall only add two Suspicions more, which may be further Instances of the Established Laws and Customs of Nature.

* 1.18And first, it is a Question, whether those Pla∣nets, which move about our Globe, keep such constant Bounds in their Motion, and move in such Lines as Astrologers teach they do. And if we consider the vast variety of Bodies, contai∣ned in and about our Globe, it can scarce be ima∣gined, that Nature should always keep to one constant and regular way of Acting, but that in several Particulars, she must deviate and ope∣rate variously; for not to mention, that Astro∣nomers have observed, even Natural Days to va∣ry in Length; and have disputed much concern∣ing the Anomalic assigned to the Motion of the Sun's Apogeum; The Sun it self hath been sometimes observed, to be even obscured by o∣pacous Matter, as in Caesar's time, and at the be∣ginning of Augustus his Government; when the Sun was for near a whole Year obscured. To which we may subjoyn the Number, Duration, and Vastness as well as Motion of some Co∣mets.

And I am informed, that in the Northern He∣misphere, in that part of the Galaxy, which is not to be discerned by us, there are certain

black, and near the Northern Pole, white Clouds, which move along with the Galaxy in twenty four hours; and these may be discerned by those that sail 18 Degrees South Latitude; but I shall not insist upon these as Arguments, since I suspect those black Clouds to be nothing but the Azure Sky appearing through the Galaxy, and those white ones, to be only Constellations, like those of the Galaxy or the Belt of Orion.

* 1.19But having hinted, that Nature may not al∣ways be exactly regular in the Motion of Planets, &c. I shall here intimate, that sometimes we may think, those Motions which are Periodical and return at set times, irregular; because we live not long enough to observe the frequent Returns of such Changes, as we usually esteem Prodigies in Nature; for it would as much be thought strange, to see Trees blossom, and Fruit in the Summer, to a Man that lived but one Year, as several other Phaenomena are strange to us, who have not lived long enough to have observed such Phaenomena in their Periodical Turns before: So before the different Appearances of Saturn had often been observed, they were thought Pro∣digies.

But it is most remarkable, that several Stars have Periodically appeared and disappeared se∣veral times in the same Place, as hath been ob∣served in the Girdle of Andromeda, and about the Swans Breast, and another amongst the fixed Stars in the Whales Neck. These I say are most remarkable, because they not only confirm what I have been saying of the Periodical Appearan∣ces of some Phaenomena; but invalidate the Phi∣losophical Systems of some, who allow of no

Vortices beyond the concave Surfaces of the Fir∣mament:* 1.20 But if rather than to allow of Vortices beyond the Surface of the Firmament, we would imagin the Stars, which appear and disappear, to have dark and light Hemispheres, which Perio∣dically turn towards our Globe; it will still be an Argument to question the Uniformity of the Motions of some of the Globes of the Universe; since at so vast a Distance, such considerable Al∣terations are observable.

But to conclude this Chapter; It may be a que∣stion, whether such prodigious Changes as are sometimus observed, may not by being frequent∣ly repeated, become a Custom, and have a Right to be reckoned amongst the Laws of Nature.

CHAP. III. Of the Temperature of Subterraneal Regi∣ons as to Heat and Cold.

FOr some Reasons, having been unable to ex∣amin into the Temper of the Air in subter∣raneal Regions my self, I shall rather give such an Account of it, as I have received from se∣veral Persons.

* 1.21And first, I shall relate a Story of the Tem∣per of the Air observed by a Chymist, who pur∣posely travelled into Hungary, which was the following: That going down into a Grove, at the first Entrance of it, he perceived the Air sensi∣bly warm; but presently after for a quarter of an

hour in his descent, he felt it considerably cold; which cold Region being passed, he began to perceive it sensibly warmer, and the lower he descended the hotter it grew; so that, in the low∣er Veins, it was hotter than the Air above ground is usually in Summer: And this Relation was confirmed by a like Observation made by a Physitian, who told me, that in a Mine, whose de∣scent did not much exceed an hundred Fathom, the cold Region was extended near to the bot∣tom of it. And this Relation is agreeable with what Morinus affirms, viz. That the Cold Regi∣on, in an Hungarian Mine, which he visited, was extended 80 Fathom, after which the Heat sensi∣bly increased, the lower he descended; and the same Author affirms, that besides the different Tempers of those Regions, there is likewise ob∣served, a different Degree of Heat, in the hot Region, correspondent to the different Seasons of the Year, viz. Winter and Summer.

* 1.22These things premised in General, I shall now proceed to consider the Particular Regions of the Earth in the four following Propositions.

PROPOSITION I.

The Bounds as well as Temperature of the first Region are very different. The Reason of both Parts of which Proposition are plain; since the Sun Beams must not only penetrate deeper in the Summer than the Winter; but also, because the solidity or porousness of several Parts of the Earth may dispose the Soil to Heat or Cold∣ness.

But to proceed, it is remarkable, that the up∣permost Region is much more temperate, because both the violent Impressions of Sun Beams, and rugged Winds, are kept off by the sides of those Subterraneal Cavities. And that the Power of the Sun Beams is much weakned by those sides, is plain; since, by such like means, the Heat of the Sun may be so broken, as to preserve Ice from thawing all Summer; and not only so, but if those subterraneal Cavities be sufficiently guarded with a Cover of Brick, well clayed over; and be, by that means, preserved from any Intercourse with the External Air, it may be preserved without digging deep into the Ground, as is observed in the South Part of France; so that, though the Coldness of Subterraneal Cavities may conduce, yet it is not altogether requisite to preserve Ice from a Thaw.

But the subterraneal Regions are not only pre∣served from excessive Heat, by preventing the Intercourse of the Internal and the External Air, but may be considerably lessned in such Cavities as are considerably exposed to the open Air: as I my self have observed in an Iron Mine not above twelve foot deep.

As as it is to be observed, that this cold Re∣gion of the Air is not apt to be influenced by external Heat in the Summer, so neither is the hot Region subject to be altered much by the ex∣ternal Cold in Winter; which appears from the smoaking of some Springs in Winter, which are supplyed with Water, which had run a conside∣rable depth in the ground, or passed through some Earth that was fitly disposed to warm it in it's Passage.

But further, that Winters Cold is much more disposed to influence the superficial Region of the Earth than the hot one which lyes under it, appears from Reason it self, and may be further confirmed by observing, that even Water in freezing los•••• it's Fluidity, and puts on the Form of Ice, first in those Parts which are most contiguous to the Air, and subject to the Influ∣ence of External Cold: And it is observed, not only in England, but also in Russia, that if Wine or Beer be kept in a Cellar well roofed over, and about twelve foot deep, it may be preserved from freezing, notwithstanding the Violence of external Cold; where it is to be observed, that the Warmth of those Vaults, does not only de∣pend on the Exclusion of External Air, but also on the Steams of those fermenting Liquors, toge∣ther with some subterraneal Steams, which are gathered there, and hindred from flying away.

PROPOSITION II.* 1.23

But to proceed to the Second Proposition, which may be comprized in the two following Members; As first,* 1.24 That the Temper of the Second Region of the Earth seems to be colder than that a∣bove or that below it. This is both confirmed by Observations already cited, and also by Reason; by the latter, because the Earth, being a Body compounded of Parts less agitated than those a∣bout our Sensory, they must consequently cause a Sensation of Cold;* 1.25 and why that Region should have it's Parts less agitated, than those about it is plain, because it lyes remoter both from the In∣fluence

of External, as well as Subterraneal Heat.

But here it is to be noted, That though I say, the middle Region is coldest, yet I would only be understood to mean a comparative Coldness; for I by no means think that Region to be posses∣sed with the most intense Degrees of Coldness, since neither Ice or Snow have been ever obser∣ved to be found in it: And though it be compara∣tively colder than those Regions about it; yet, that it is not the coldest may be hence argued, be∣cause it is observed in the Summer, that the Ex∣halations which steam from the middle Region are sensibly warm at the Orifice of the Grove; which they could not be, were the middle Re∣gion through which they passed extreamly cold.

* 1.26But to pass to the second Member of this se∣cond Proposition; It is observed, That in several Places, which may be referred to this middle Region, the Temperature of the Air is different at the same Seasons of the Year. Which is evident both from Reason and Experience.

And first, from Experience it hath been learnt, by those who have often been in those Hungari∣an Mines, as well as some here in England. And indeed if we consider the different Heat in diffe∣rent Climates; but more peculiarly the Difference in Soils, it will not be less consonant to Reason; for the Soil may be more or less porous and com∣pact;* 1.27 and may have different Substances mixed with it, or run through it, which may alter the Temper of it; for there is not always that Re∣gular Order in Nature, which is in our Thoughts of her; since Salts, Marchasites and Minerals are

dispersed through the middle as well as the lower Regions of the Earth; and may, by impregnating those Fluids which run through the Earth, cause different Refrigerating Effluvia to affect various Parts of the same Region; as if, in one Place, it be impregnated with Nitre, and in another with Marchasitical Earth; the Coldness of the former must render that Part of the Region the colder of the two. Besides, the Temper of them may differ upon the account of the Soil it self, which varies according to the several Degrees of it's Maturi∣ty; so that for these Reasons, the Temper of Effluvia may be different in the same Place at one time from what they are at another in the same Place; not to mention those Differences which it may undergo by several other Accidents, and the Subterraneal Effluvia, which ascend more or less from the lower Regions.

And before I leave this Proposition, it may be necessary to advertise, That the different De∣grees of Heat or Cold, in the several Regions of the Earth, are not easily discover'd by those Thermoscopes, which are usually made use of, to distinguish such Differences; because the Pillar of Air, which presses upon the Liquor may dif∣fer in it's Pressure, according to the Length of it; it being longer, and consequently heavier, the lower it descends.

But to pass to the Third Region compriz'd in the following Proposition,* 1.28 viz. That the Temper of the Third Region is warm, which Warmth va∣ries in several places. That it is Warm, and that that Heat varies in several places, I think is suffi∣ciently attested, by the several Persons that have gone down into those Mines; but as for the

Causes of it, those are not so easily discover'd: for I am not a little inclin'd to suspect, That con∣sidering the Closeness of those Cavities in which they work, the Effluviums of their own Bodies, and of the Metal they work in, may in some mea∣sure contribute to it.

* 1.29But to pass by this Suspicion, I shall rather briefly intimate, That I conceive the Earth to be stocked with store of Subterraneal Fires; and that several Calorifick Qualities, being carry'd up through Clefts and Veins in the Earth, cause a Sensible Heat to be diffus'd through the whole. And that there are such Steams, appears mani∣festly from those Damps, which are often ob∣serv'd in Groves; not only in England, but Ger∣many, Bohemia, Hungary, &c. which are some∣times so Bituminous and Sulphureous in Smell, as to be apt to take actual Fire.

But one thing I must intimate here, which is, That tho' I am induc'd to believe, for some Rea∣sons, this Argument valid; yet, I am not without a Suspicion, that notwithstanding the Aptness which these Exhalations have to take Flame; yet, even several cold Steams may rise from the lower Parts of the Earth, which may acquire Heat in the Upper Regions; for we see, that several Substances, which are apt enough to take Flame, have not the least sensible Heat in their Parts before; nay, are so far from that, that Salt-Petre, which is so apt to flame, will, by being dissolv'd in Water, add a considerable Degree of Coldness to it: And the like may be observ'd in Spirit of Wine, whose Spirit, tho' easily in∣flammable, affects not the Touch with the least Heat, if rais'd in the Form of a Vapor.

But that which inclines me to be of the Opinion just now mention'd, is, That not only Morinus, but several others have observ'd, the Exhalations of Mines considerably hot in Summer time. And the Experienc'd Agricola hath oserv'd, That the Mi∣neral Steams which pervade the Earth, are so powerful, as not to permit a Hore-frost to lie upon the Ground which they lie under; and the like hath been observ'd upon Coal-Mines: And I remember, that an Acquaintance of mine shew'd me a piece of Land, which was so powerfully penetrated with warm Effluvia, that Snow would not lie upon it above two Days, were the Wea∣ther never so cold, which hath been confirm'd by frequent Observations; except where Layers of Rock, or some other Stony Concretes, obstruct∣ed the Passage of those Mineral Steams. To which may be added, That the Steams near Gold-Mines are so copious in Hungary, as to give the Leavs of the Trees a Golden-Colour.

But notwithstaning these Instances, I am apt to doubt, that there are several Parts of the third Re∣gion, which by reason of their Remoteness from such Subterraneal Fires, have not that Heat. But since these things are but uncertainly guess'd at, none having so great Curiosity, as to be at the Charges to dig deep enough without prospect of Gain, I shall rather proceed to consider, That,* 1.30 besides the foremention'd Causes, there is in some Mines such a degree of Heat, as cannot be ac∣counted for without another Cause; the Inca∣lescence being so great, as not to be produc'd without the Concourse of some other Mineral-Steams, or Water to work upon, and promote the mutual Actions and Operations of the Vo∣latile

and Active Parts of those Mines. And that such Incalescenses may be produc'd in the Bowels of the Earth, I have elsewhere observ'd: And further, That Immature Minerals, such as Marchasites, whose Parts are impregnated with Vitriol and Sulphureous Parts, may, by reason of their Aptness to be dissolv'd, be able to cause such Effects, we may be induc'd to believe, because Vitriol hath not only been found in several Mines in Hungary; but likewise such Strong and Cor∣rosive Effluviums, as were very offensive to Respi∣ration, and in a little time fatal to those that ven∣tur'd to work in them. And there is one thing further Remarkable, That several pieces of Vi∣triol, which were found in the Bottom of some of those Mines, of a soft Consistence, presently, when brought up and expos'd to the open Air, grew hard, retaining several Golden Streaks in it.

But there is one thing here to be noted, which is, That, in Groves which are very deep, the Air is so unfit for Respiration, as to want a frequent Ventilation; so that the Miners are wont to sink an Air-Shaft, as they term it, some Paces off the Grove, that the Air passing from the Grove to that, by a short of Channel, or Ventiduct, (which Agricola lib. v. and vi. de re Metallica, calls Cuni∣culus) might keep the Internal Air in such a Tem∣per, as to make it fit to breathe in; tho' the Mines were 200 Yards deep.

And Agricola, in his Book de re Metallica, gives further the following Account of the Course of the Air in these Cuniculi, or Air-Shafts, in these Words: Aer autem exterior se suâ sponte fundit in Cava Terrae, atque cum per ea penetrare

potest, rursus evolat foras. Sed diversa Ratione hoc fieri solet; Etenim Vernis & Aestivis diebus in altio∣rem puteum influit & per Cuniculum vel Fossam laten∣tem permeat, ac ex humiliori effluit similiter iisdem diebus in altiorem Cuniculum infunditur, ac interje∣cto puteo defluit in humiliorem Cuniculum atque ex eo emanat. Autumnali & Hyberno Tempore contra in Cuniculum vel Puteum humiliorem intrat & ex altiori exit: Verum ea fluxionum Aeris Mutatio in temperatis Regionibus fit in initio Veris, ac in fine Autumni; in frigidis autem, in fine Veris, & in initio Autumni: To which he adds, Sed Aer utro∣que tempore antequam cursum suum illum consuetum constanter teneat, plerumque quatuordecem dierum spatio crebras habet mutationes, modo in altiorem Pu∣teum vel Cuniculum influens, modo in humiliorem. And these things may give us some Reason to believe, That there are in the Earth seve∣ral Periodical Changes in the Temperature of those Regions, which deserve our Consideration. But having several times enquired about these things, I am inform'd that the Air generally goes in the same way, both Winter and Summer, en∣tring the Air-Shaft, and coming out of the Per∣pendicular Grove.

But to conclude this Chapter: From what hath been said, it may appear, That tho' in some Mines, the Earth seems to be distinguish'd into three Rgions, yet generally the Temperature of the whole is various and uncertain: And much more uncertain is it, what is the Constitution of the Central Parts of it; and whether that be divided into Distinct Regions, or what is the State and Texture as well as Consistency of its Parts, we must be content to be ignorant of; since one of

the deepest Mines we have heard of, being men∣tion'd by Agricola, in his Book call'd Bormannus; Cap. 12. was at Cotteberg, which exceeded not 500 Fathom; and if, according to Gassendus, the Semi-diameter of our Globe be 4177 Italian Miles, what a Superficial Knowledge must we have of it, who have not been able to make our Observations above 500 Fathom; and that too, in but a small Part of it's Orb.

CHAP. IV. Of the Temperature of the Submarine Re∣gions, as to Heat and Cold.

THE following Chapter relating to the Temper of Submarine Regions, I would be suppos'd to mean, by that Term, not such as are beneath the whole Ocean, but only such as are beneath its Superficies; concerning which, I shall not relate what follows, as upon my own Observation, but only as receiv'd by Informa∣tion from others, who have dived into them.

* 1.31And First, I shall only assign to this Element two Regions; the One bounded by the utmost Penetrations of the Rays of the Sun, and other Calorifick Causes; the other extending it self to the utmost Depth of the Water.

* 1.32According to which Division it will follow, that the Upper Region must vary in it's Extent; according to the Difference of the Climate, and the Heat of the Sun, (supposing the Warmth of it

not to proceed from Subterraneal Effluvia;) and not only in the Extent, but the Temperature of that Region; which may not only be vary'd by the Influence of the Sun, but also, by the dif∣ferent Nature of the Soil about the Shores, being either Nitrous, or Marchasitical; as also by the Shallowness of the Water, which may contribute to the Warmness of it, the Rays of the Sun be∣ing refracted by the Subjacent Sands. To which Causes may be added the Influence of Subter∣raneal Fire: An Observation favouring which, hath been made by Monsieur de Ponts, in his Voyage to New France; in the way to which he observ'd, That in one Place the Water was very warm, as well as the Wine, which lay in the Boat, tho' there was no sensible Alteration in the Air; and that this continu'd for three Days; whereas, on the 21^rst of the same Month, it was for 2 or 3 Days observ'd to be as cold.

* 1.33These things in short being premis'd, con∣cerning the Upper Region, I shall now pro∣ceed to the Lower, which is Cold; the Parts of Water being in a less violent Agitation than our Sensory: And that the Lower Region is sensibly cold, is not only consonant to Reason, but also confirm'd by the Observation of those, who have dived a considerable Depth, not only in the Northern Seas, in Africa and America; but it is also further evinc'd, by what is commonly practised at Sea, viz. to let down Bottles of Wine into the Sea all Night; which, by being immers'd in the Water, will acquire a considera∣ble Degree of Coldness. And I am also inform'd by an Observing Traveller, that having let down about 400 Fathom of Line, with about 30 pound of

Lead at it, thirty five Degrees North Latitude beyond the Line; the Lead, when drawn up, was as cold as Ice.

From which Instances it appears, that the Air and Water so far agree, that the Parts of them being put into Motion, by External Causes, they acquir'd each a considerable Degree of Warmth; but, being remov'd and separate from those Causes, put on a contrary Quality; so that the Air and Water seem chiefly in this respect to differ, viz. in their inverted Order.

But further: From what hath been deliver'd, it appears, That tho' the Submarine Regions be sensibly colder, the nearer the Bottom; yet their coldest Region does not, by any of the afore∣mention'd Phaenomena, appear to be the Summum Frigidum; for tho' I have several times frozen Salt∣water, yet it does not appear, that there is the least Ice generated in the Bottom of the Sea; since from the Bottom of the great Ocean 35 Degrees South Latitude, Gray Sand hath been brought up, where the Water was no less than two hun∣dred and twenty Fathom deep: But yet there is one Caution to be added, which makes this Observation the less to be rely'd on; which is, That one Reason why no Ice is to be found in the Bottom of the Sea, may be the Unaptitude of Salt-Water, more than of Fresh, to be congeal'd; it requiring a much greater degree of Cold to freeze Salt-Water, than Fresh.

CHAP. V. Relations about the Bottom of the Sea.

* 1.34THAT the Bottom of the Sea is usually Salt and Cold, is a very common Obser∣vation; but being desirous to be more nicely inform'd, about what occurs in that Region; I have been told by several, who have in long Voyages, fathom'd in several places, that the Bottom of the Sea is rough, with considerable Inequalities, and Precipices; so that in a small Space a little Depth of the Sea hath increas'd to a hundred Fathom, and decreas'd as suddenly: There being likewise found several other Ine∣qualities and Hills, observ'd in Places about 30 or 20 Fathom deep; where a Line of 16 Fathom, would upon the next Cast require 35 or 40 to reach to the Bottom of the Sea; and the like Observations I have receiv'd from seve∣ral Experienc'd Mariners: Amongst which, I transcrib'd the following Account, from some Notes left in England, by one who had made a Voyage to the East-Indies: The Account was this.

February 12. After our Observation, seeing the Ground under us, we heaved the Lead, and had but 19 Fathom Rocky Ground, then hal'd by N.N. E. the Wind at N.W. and found our Wa∣ter to shoal from 19 to 10 and 8 Fathom, hard Coral Ground; then suddenly deepned again from 8 to 20 and 22 Fathom Sandy Ground; and then suddenly saw Rocks under us, where

we had but 7 Fathom, and the next Cast 14 Fathom again; and so having run N. N. E. from 6 in the Morning, till 12 at Noon, about 19 Mileswe deepned our Water from 16 to 25, and the next Cast no Ground with 35 Fathom of Line.

* 1.35But besides the Inequalities to be taken No∣tice of at the Bottom of the Sea, there are several other Things to be observ'd; amongst which the Gravitation of the Water, is remarkable; and tho' it be disputed amongst Philosophers, whether there be such Gravitation or not; yet that there is, appears from several Experiments.

And First, If a Glass-Cylinder, with one End open, be immerg'd in a Glass-Vessel, it may be observ'd, That as the Cylinder is press'd lower, the Air by the Pressure of the Water, will be squeez'd higher and higher, the water rising gra∣dually below it in the Cylinder. And the like hath been observ'd by several Persons, who have dived in a Diving-Bell, not only in the Northern Sea, but upon the Coast of Africa; where as the Bell went deeper and deeper, the Air became more compress'd, and the Water accordingly rose higher and higher in the Bell. And some∣times the Pressure hath been observ'd to be so powerful, that I have been inform'd by one who let down a Glass-Vial into the Sea, near the Straight's Mouth, that, having let it sink about 40 Fathom, it was burst in pieces, by the out∣ward Pressure of the Water; to which he added, That, having let down an Aeolipile of Metal, and sunk it about 60 Fathom, he observ'd when it was drawn up, that the sides were in several places bruis'd and compress'd by the violent Pres∣sure of the Water.

* 1.36Another thing observable in the Bottom of the Sea, is, That tho' the Violence of Storms may disturb it, where it is shallow; yet where it is considerably deep, the nearer the Bottom, the more calm and undisturb'd it is. And this hath been confirm'd by the Observations of Divers, who have taken Notice, That tho' the Waves were six or seven foot high, yet, at fifteen Fa∣thom deep, the Water was very little disturb'd, only the Mud was rais'd, which made the Water dark; and what is very remarkable, is, that the Person that dived inform'd me, that having stay'd a considerable depth for some time, he found, when he came up again, a Tempestuous Storm, which had risen when he was in the Water, without being taken Notice of by him below. And the like hath been observ'd, near the shoar of Manar, in the East-Indies, where they dive for Coral, in a Sea, that lies be∣twixt the Island of Ceylon, and the Cape of Co∣mori, which is usually very much disturb'd; in∣asmuch as it lies near the Indian Ocean, and the Gulf of Bengala, formerly call'd Sinus Gangeti∣cus. And it hath elsewhere been observ'd, That, in considerable Storms, the Seas have not been disturb'd over the Depth of 4 Fathom.

* 1.37And to these Observations I might add, had I sufficient Evidence to build upon, That, having enquir'd, whether upon Ebbing and Flowing of Tides, the Motion of the Water was continu'd to the Bottom; I have been told by some, that it does almost stagnate, and by others, that the Current of the Water above, is different from the Tendency of that below. But not to rely upon these Relations, I have been inform'd,

by a Person who made his Observations beyond the Cape of Good Hope, in the Southern Sea, that, having let down his Plummet, about an hun∣dred Fathom, he found, that the Plummet be∣ing suspended in the standing Water, made the Boat turn to the Tide, as if it lay at Anchor. And that there is such a Stagnation of Water at the Bottom of the Sea, hath been likewise confirm'd to me, by Observations made near the Coral Fi∣shery, in the East-Indies.

CHAP. VI. Further Relations about the Bottom of the Sea.

THAT the Air, is not only necessary to the Preservation of Animals, but also promotes Vegetation, and the Growth of Plants, I have elsewhere observ'd; but since several Trees and Plants are observ'd to grow under Water, I shall further observe what Informa∣tions I have receiv'd concerning them.

* 1.38And First, To what hath elsewhere been de∣liver'd concerning the Growth of Coral under Water, I shall add, That I am inform'd by one, that saw it near Algiers, that Coral, when first taken up, is not only soft and flexible, but very pale; yet when the Bark is taken off, and it is expos'd to the Air, it's Natural Redness presently appears: To which he added, That

having broke several Pieces, he found it much paler within than on the outside; and that there were several black Knobs on the extream Parts of the Twigs; the place from whence this Coral was taken, being about nine or ten Fathom deep. And I have been further inform'd by one that sail'd to the East-Indies, that upon a certain sort of Coral he hath observ'd, certain round Berries of a very pleasant Colour.

* 1.39To these Relations I shall add, That Divers have not only observ'd Trees to grow under Water, near Manar, which bore Leaves like those of a Laurel, but that not far from the Coast of Mosambique, in Africa, several Trees are ob∣serv'd to grow under Water, whose Fruit and Leaves are like those of the Tree in America, which bears a Fruit call'd Acayu.

But an Observation more Valuable, is con∣cerning the Maldavian Nut, call'd Coco, which by experienc'd Divers, are found to be the Fruit of a Tree, which grows at the Bottom of the Sea, which are either gather'd by the Divers, or torn off by the violent Agitation of the Wa∣ter: In which Fruit it was observ'd, that, whilst it was under Water, it was very soft; but when it had been expos'd a considerable time to the Air, it became very hard.

CHAP. VII. Observations and Experiments about the Salt∣ness of the SEA.

* 1.40THE Saltness of the Sea, by several Peripa∣teticks, hath been judged to proceed from the Influence of the Beams of the Sun upon the Water; but with what little reason may easily appear from those standing Lakes and Ponds, whose Water, notwithstanding the Influence of the Sun, continues fresh: And that it neither pro∣ceeds from the Influence of the Sun, nor any o∣ther external Heat may be argued, since though some fresh Water be drawn off by Distillation, and consequently undergoes as great a Degree of Heat, as it can be supposed to do from the Sun Beams, it yields not so much Salt as is to be found in some Water, never exposed to such Heat; which Salt differs very little from Sea Salt, only that it is whiter, being more clear of it's faeces, and free from a Mixture of earthy Parts.

And though some alledg in favour of Aristo∣tle's Doctrin, That Scaliger affirms the Sea Wa∣ter to be saltest in it's upper Region; yet it will appear, by comparing the Saltness of the super∣ficial Parts of the Sea with the bottom, that the Observation was ill made, and does not general∣ly hold; neither will it favour his Doctrin, should it be alledged, that Sea Salt dissolved in Water, otherwise than common Salt christalizes at the Top of the evaporated Solution; for conside∣ring how much Salt Water must be impregnated

with; and that the Quantity of Salt in Sea Wa∣ter hath been observed by a Dutch Geographer to be only as One to Forty;* 1.41 it's Disposition to cry∣stalize can be no Argument of the swimming of Sea-Salt more on the top of the Water than the other Region.

But though I differ in this Point from the Pe∣ripatetick Philosophers; yet I do not believe, on the contrary, with some, that the Gravity of Salt makes them sink the more to the bottom; since the intestin Agitation of the Parts of the Water continually shifting Places must consequently car∣ry it along with them; which Consideration joyned with another, which is, that I have not u∣sually observed, Metalline Tinctures stronger at the top than bottom, might perhaps give a sus∣picion to some, that the present Argument is less cogent, notwithstanding the specific Gravity, be∣twixt Metals and their Menstruums does much exceed that betwixt Salt and Water.

But further in behalf of the Peripatetick Do∣ctrin, it is urged out of Linscotten, that, at Goa in Portugal, it is usual for their Slaves to dive, and fetch fresh Water from the bottom of the Sea; but tho' this Matter of Fact were true, yet no ge∣neral Rules could be drawn thence; because Ex∣perience tells us, that in other Places it is contra∣ry. Besides it might be probably guessed, that,* 1.42 were it true, that fresh Water might rise by cer∣tain Springs covered over with Sea Water, as well as that several Springs in other Places should be under Water upon the flowing of the Sea: And that there may be such Springs is so far probable, that the curious Hungarian Gover∣nor de admirandis Hungariae Aquis, says, That in

the River Vagus, near the Fortress Galgotium, Veins of hot Water rise up in the very bottom of the Water; his Words are these, Ne{que} in Ripa tan∣tum eruuntur calidae, sed etiam intra amnem, si fun∣dum ejus pedibus suffodias; calent autem immodicè, &c. And the like hath been observed upon the Neapolitan Coast.

But not to urge these Relations, I shall inti∣mate briefly, That an ingenious Acquaintance of mine, who lives in that City, hath informed me, that that fresh Water is not fetch'd so deep as to be suspected to rise from such Springs; but that it is rather the fresh Water which runs into the Sea from a River not far off, before it is mixed with the Salt Water; which Conjecture I the ra∣ther believe, because near Mouths of Rivers it hath elsewhere been observed, that fresh Water hath for some time floated together, without being perfectly mixed with the other Stream.

And as for Scaliger's Opinion, it might be ur∣ged against it, that by a Vessel so artificially contrived, that it might be opened at the bot∣tom of the Sea to take in Water, the Water drawn up hath been found to be Salt. But since it may be urged against this, that the Salt Wa∣ter being heavier than the fresh, as it was draw∣ing up might be mixed with it, by pressing into the Vessel; I shall add Instances not lyable to such Objections; for it hath been observed, not only at the Cape of Comori, but elsewhere, by Divers, that the Water is as Salt at the bottom as at the top; and I am informed, that Divers have not only under the Torrid Zone observed the Wa∣ter exceeding Salt, but have brought several Lumps of Salt from the bottom with the Sea:

And the like Saltness of the bottom of the Sea hath been discovered near the Straights of Gi∣bralter's Mouth: And further, that I might not only be sure, that the Sea was thus Salt at the bottom, I procured two Quarts of Sea Water, the one taken up at the bottom of the Sea and another at the top; in which, though there was some Difference in Colour; yet being Hydrosta∣tically tryed, there was no sensible difference in the specifick Gravity of them.

But to make out what I have before intimated, viz. That the Freshness of the Water in the bot∣tom of the Sea near Goa might be produced by the Rise of some Springs under Water; though it may be objected, that the specifick Gravity of the Salt Water, would in some measure obstruct the Rising of fresh Water: Yet this Objecti∣on will easily be answered, if we consider, that according to what we have delivered in our Hy∣drostatical Paradoxes, and also what Stevinus hath observed, let the Quantity of Water be never so great, no more can resist the Rising of such Springs, but that Pillar of Water which lyes o∣ver them in a perpendicular Line; and if the Spring takes it's Rise from some high Place, so that the Weight of that Water which lyes in the Vein, be heavier than the perpendicular Pil∣lar of Sea Water, the Rising of it can by no means be hindered by the Pressure of that incumbent Water.

But to explain and confirm this Paradox, I shall add, that having procured a long Glass Syphon, part of it being inverted so as to form a short Leg, I filled it with Claret, stopping the Orifice of the longer Leg with my Thumb, which Sy∣phon,

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being immersed in Salt Water contained in a Glass Vessel, and the Orifice of the longer Leg being opened, the Claret, notwithstanding the Pressure of the Salt Water, presently rose up in it in the Form of Clouds, which lasted till the Liquor in the Pipe was brought to a just Aequi∣librium with the incumbent Pillar of Salt Wa∣ter.

* 1.43But to pass on to the Cause of the Saltness of Sea VVater, I deny not what Gassendus and other Moderns teach; but grant, that the Saltness pro∣ceeds from a Solution of Salt in the VVater; yet I am apt to suspect, that that Saltness is not only supplyed by those Salt Rocks, which may be con∣tiguous to, or near the Water; but that the Sea is in a great Measure supply'd, by Salt wash'd away and carry'd into it, by Springs and Rain-water, which float into the Ocean. And I am the more confirm'd in this Suspicion, because several Chymists have not only found Salt in some Waters; but have obtain'd a good Quan∣tity of common Salt upon refining of Salt-Pe∣tre, which according to Sir Francis Bacon, is in most Soils, which are not spent in Vegetation, or wash'd and consum'd by the Sun and Rain.

But not to insist too long on these things, it is not only probable, That the Salts in the Earth, may, by this Means, contribute to the Saltness of the Sea; but that, from what hath been be∣fore deliver'd, such Salts may be communicated to it by latent Springs, not to be taken notice of or discern'd by us. And further, That such Salt as abounds in the Earth, may supply the Sea with most of the Salt which is perceiv'd to be in it; we are to render it further probable,

to consider, That the Sea-Salt, and that, are agreeable in the main, with each other; since they have almost the same Shape and Taste, &c. the former of which will appear by Evapora∣tion and Crystalizing them; and as for some small Difference to be perceiv'd betwixt them, that may easily arise from those Bituminous and other, as well as Nitrous Bodies, which flow into the Sea, and which may be mixed with them, both by the internal Agitation of the Parts of the Water, as well as the outward Action of the Sun and Air.

And that there is such Salt dissolv'd in Sea-Water, might be probable, if it were possible so to raise the fresh Water it was dissolv'd in, by Distillation, as to leave the Saline Parts be∣hind; but not now to mention, that not only I, but the Judicious Sir John Haukins, in his Voy∣age to the East-Indies, have, by distilling of Salt-Water, obtain'd from it a wholesome fresh Water; I shall, without making a long Digression, proceed to answer an Objection, which is urg'd against what I have deliver'd, viz. That if the Springs acquir'd such a Salt∣ness by running through the Earth, it would be discernible before they emptied themselves into the Ocean. To this I shall answer, That besides those fresh Springs which are visible to us, there may be several others which lye too deep for us to take Notice of: But here it may be requisite to take Notice, That I do not say, That the Saltness of the Sea wholly depends on such Sup∣plies; but that they contribute to the Saltness of it.

* 1.44Having said so much of the Saltness of the Sea and its Causes; it may be now seasonable to observe, from whence proceeds that Bitter∣ness remarkable in some, if not most Sea-Wa∣ter; which, we conceive, may proceed, part∣ly from the external Power of some Catholick Agent, and partly, from those Bituminous Bo∣dies which are carried along with Spring-Wa∣ter into the Sea, which hath been visibly appa∣rent in the Island Barbadoes, where that which they call Barbadoes Tarr, hath been seen to flow from the Rock into the Sea; and to these Causes may concur some Subterraneal Exhala∣tions and Effluvia, which I have elsewhere taken notice of to flow from and pervade the Earth. And as for those different Tastes which are per∣ceiv'd in the Sea at several Places, it is no less probable, that they proceed from other adven∣titious Bodies mix'd and incorporated with the Sea-Water; for that the Sea-Salt which is dis∣solv'd in it, is not a simple Salt, but a com∣pound, I have been induc'd to believe by a Salt which I obtain'd from it.

And that some Catholick Agents may work Changes in the Saltness of the Sea, which it would not otherwise have, by a bare Solution of those adventitious Bodies that are mix'd in it, I have Reason to believe, since I have found, That by keeping the Parts of Sea-Water in A∣gitation, by a continued digestive Heat, it hath considerably differ'd in Taste, from a bare Solu∣tion of Sea-Salt in Water. And for a further Confirmation, That the Saltness of the Sea is vary'd in several Places, I shall barely intimate those several Colours, different Qualities, and

stupendious Multitudes of adventitious Corpus∣cles which are mix'd with it.

* 1.45But to proceed, amongst the various Obser∣vations to be made about Sea-Water, it is worth our Notice, That if it be kept from A∣gitation, it will in a short time stink; which I have not only observ'd, by keeping some of it in a Runlet for some time; but also, I am in∣form'd by one, who, in a Voyage, was for some days becalmed, that the Sea, for want of Agitation, stunk so much in twelve or fourteen days, that the Smell was almost intolerable; which continued till the Winds put the Water into Agitation. Which agrees with what Sir John Hawkins hath observ'd, who relates the following Story: Were it not for the Moving of the Sea, by the Force of Winds, Tides and Currents, it would corrupt all the World. The Experience of which I saw Anno 1590, lying with a Fleet about the Islands of Azores, almost Six Months, the greatest Part of the time we were becalmed, with which all the Sea became so replenished with several sorts of Gellies, and Forms of Serpents, Adders and Snakes, as seem'd Wonderful; some green, some black, some yellow, some white, some of divers Colours, and many of them had Life, and some there were a Yard and a half, and some two Yards long; which had I not seen, I could hardly have be∣liev'd; and hereof are Witnesses all the Company of the Ships, which were then present, so that hardly a Man could draw a Bucket of Water clear of some Corruption. In which Voyage toward the End there∣of, many of every Ship fell sick of this Disease, and dy'd apace, but that the speedy Passage into our own

Country was a Remedy to the Crazed, and a Pre∣servative for those that were not touched.

* 1.46As for the different Degrees of the Saltness of the Sea, I shall deliver what I have been in∣form'd of, as briefly as I can. And First, It hath been observ'd, by one to whom I gave a Glass conveniently shaped to try the specifick Gravity of the Water, that it grew heavier and heavier as he came nearer the Line, till within about thirty Degrees Latitude; from whence to Ja∣maica he observ'd no Alteration in the specifick Gravity in the least. And in Confirmation of this I am likewise inform'd, by one, who for his own Satisfaction weigh'd the Water, both under the Aequinoctial and at Cape of good Hope, and found that the Weight of both was the same. To which may be added that it is com∣monly observ'd at Mosambique, one of the hot∣test Places in the World, that the Sea is so salt there, that it bears up the Ships a considerable Height out of the Water, more than in other Places; and that the Water may be much salter in one Place than another, by having more Salt dissolved in it, does not only appear from what hath been said, but also from what is frequently observ'd in the different Strength of Brine-Pits.

But to pass from what I have learnt by In∣formation, to what I have observ'd my self con∣cerning the Proportion of Salt to the Water it was dissolv'd in, which I have observ'd in Sea-Water, betwixt England and France.

* 1.47The first Experiment I made to discover the Quantity of Salt was this, that having, in a Viol, weigh'd an equal Proportion of Sea-Water taken up at the Surface of the Sea, with com∣mon

Water, the Weight of the former exceed∣ed the latter of forty fifth Part; but these Li∣quors being more Hydrostatically try'd, by weighing Sulphur in them, that which in the Sea-Water weigh'd ℥ss + 10 ½ gr. in Sea-Wa∣ter, fetch'd from the bottom, ballanced the same Weight; but being weigh'd in common Water, it weigh'd ℥ss + 15 ½ gr. so that the Sea-Water was a Fifty third Part heavier than the fresh; the Difference in which way of try∣ing it, from what was observ'd in the former Tryal, I could attribute to nothing, but some grosser Saline Parts mix'd with the common Water, or some evaporated Parts of the Sea-Water.

Another way we made use of to try the dif∣ferent specifick Gravity of these Liquors, was, by Distillation ad Siccitatem in a digestive Fur∣nace, in which a Pound Averdupoise Weight yeilded ℥ss 10 gr. of Salt; so that the Propor∣tion of the Salt to the Water was as 30 and 12/100 to one, being near the Thirtieth Part.

But suspecting that the Quantity of this Salt was much increas'd by imbibing Moisture from the Air, I caus'd it to be dry'd in a Crucible, and found it weigh'd ʒiij + ss, which is about a Thirty sixth Part.

How so much a greater Quantity of Salt should be obtain'd by Distillation, is difficult to con∣jecture; yet I am apt to think, that it might proceed from some Parts of the Water detain'd from flying away, by being enclos'd amongst the cubical Salts; and this I am apter to believe, First, Because I have elsewhere prepar'd a Salt, which would coagulate and embody it self with

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Water; and Secondly, Because I am told, That a Sort of Salt is brought from the Coast of Spain, which being here purify'd and dissolv'd, will yield a double Quantity.

* 1.48Whether the Sea-Water may at some times be more impregnated with Saline Parts than at others, I conceive probable, if we consider the Supplies that it receives both from the Earth, which are carry'd to it along with Springs, and also, the sudden Additions it may receive from Subterraneal Exhalations; but these Observa∣tions being very nice, it most commonly re∣quires other Measures than what Hydrostaticks afford; for it may be observ'd, That several volatile Salts which are of no considerable Weight above common Water, may be mix'd with it without being perceiv'd; so that one may easily be deceiv'd in judging of the Salt∣ness of the Sea altogether by Hydrostaticks; because, that which violently affects the Taste, may have but a small Influence in the Balance: To confirm which I shall add, That a Bubble of Glass, having Metal in it, weigh'd ʒiij ✚ 51 ¼ gr. in Spirit of Sal Armoniack, and but ʒiij ✚ 45 ¾ in common Water. But further, I weigh'd in the same Liquor an equal Proportion of Sea-Salt brought from the torrid Zone and Sal Ar∣moniack, and found, that the Bulk of the former was, to an equal Proportion of that Liquor, as two and a quarter to one, whereas the Sal Armoniack was not above a hundredth Part, a∣bove one, and 7/10 to one, which is the more strange, because Part of the Composition of Sal Armo∣niack is Sea-Salt.

But that I might be satisfi'd what was the great∣est Degree of Saltness, that Water would be impregnated with; I shook a Lump of Salt in Water, till it would dissolve no more; and found that a Brine might be made so strong, that the Salt would be dissolv'd in five times its weight of Water.

To conclude this Discourse, I shall add one thing which hath not been taken notice of by Hydrostaticians; which is, the weight of the Sea-Salt to its Bulk of Water, which I have found to be almost as two to one; and I likewise found, that a piece of Sal Gemm, which is more pure and weighty than Sea-Salt was to its Bulk of Water about as 2 2/8 to 1.

CHAP. VIII. Memoirs for the Natural History of Mineral Waters.

THE Use of Mineral Waters are so Uni∣versal, and the Methods which some Phy∣sicians take to try them so slight; that, tho' I am satisfied it is difficult, without Experience to Ascribe Virtues to them à priori, by Reason of the Great Variety of Minerals, which may im∣pregnate them with Particles of various and very different Natures; I cannot but think, but that if we were furnish'd with a sufficient Num∣ber of Quaeres, and several Methods in order to a Discovery of them, more nice Tryals might

much Contribute to the clearing up of a Na∣tural History of Mineral Waters; since by a competent number of Experiments it might be hoped, that the Nature of those Metalline Salts, with which Mineral Waters are Impregnated, might be discovered.

Wherefore I have lay'd down such sorts of Experiments, that might be most easily try'd, viz. chiefly Chimical Ones, which may be made at home, without the Inconveniencies of atten∣ding those Mineral Fountains from whence they spring.

And because my Design is rather to improve Physick by the following Observations, than to entertain Speculative Naturalists; I have chief∣ly made it my Business in the following Papers, to consider those Waters call'd Acidulae, rather than the other term'd Thermae, because the for∣mer are of more general Use.

* 1.49But perhaps some may think that the Quares hereafter propounded may be too troublesome, and more than requisite; since the Use of Mine∣neral Waters are thought so innocent, as to be of no ill Consequence if Unsuccesful. To which it may be answer'd, that tho' when skil∣fully given, they do a great deal of good; yet they are as prejudicial if unskilfully prescrib'd; and therefore, since there cannot be too much Caution, we cannot be too inquisitive to inform our selves of their Virtues; for there may be a great many hidden Qualities in them, and they may be impregnated with several Metalline Pro∣perties, which may not be discover'd to the Eye or by common Tryals.

Besides, were such Experiments industriously prosecuted, they might help to discover several other Qualities in Mineral Waters, which are as yet unknown; for from the following Expe∣riments it is evident, that the Earth, which a∣bounds with Minerals of a Martial Nature, may be more apt to impregnate subterraneal Waters than we can otherwise imagine; for upon pouring of a Tincture of Galls filtrated through Cap-paper upon filings of Steel,* 1.50 the Liquor in half an hour became Opacous, and almost as black as Ink: The like Phaenomena to which were exhibited by Steel in an Infusion of Brasil or Log-wood made in common Water. To which we may add, that several Waters have been discover'd under ground of very different Tastes; some of which have been found to be corrosive, and others as harmless, being endow'd with se∣veral Medicinal and Useful Qualities; and I am inform'd more particularly of one, which is a Mine of Coral in Devonshire about 360 foot deep, in which was found a Water very thick and red, yet cool and Diuretick, and not in the least nauseous to the Taste.

CHAP. IX. Titles propos'd for the Natural History of Mineral VVaters, consider'd whilst in their proper Channel.

* 1.51IN order to a natural History of Mineral Wa∣ters, they ought to be consider's in three dif∣ferent Capacities: First, as they are found in their natural Receptacles; Secondly, when drawn up for use; and thirdly, with Respect to their Effects on Human Bodies. To the first of which Heads the following Quaeres may be re∣fer'd.

• 1. Within the Precinct of what Climate or Parallel, and in what degree of Latitude the Mineral Waters are to be found?
• 2. To what point these Waters lie open most in their Receptacles?
• 3. Whether the Ground in which they are found be a Plain, or how much it differs from a Plain?
• 4. If the Ground be upon an Ascent, how far they are from the botttom of that Ascent?
• 5. Whether a Recrementitious Substance ad∣heres to Stones long contiguous to these Wa∣ters?
• 6. Whether subterraneal Fires be near such Waters, and what Phaenomena such exhibit?
• 7. Whether Brimstone or Sal-Armoniack, &c. be found about the Vents of such subterraneal Fires?

• 8. Whether instead of subterraneal Fires, there are other adjacent Aestuaries? and whether such be constant or intermitting? and if so, whether periodical or irregular?
• 9. Whether Mineral Fumes of particular co∣lours or smells arise from such Aestuaries?
• 10. Of what Temper the neighbouring as well as the Soil they pass through is of?
• 11. Whether and of what Nature those Mi∣nerals are of which they pass through?
• 12. Whether the Mineral Waters be origi∣nally fresh, and derive their Virtues from the Soil they afterwards pass through?
• 13. Whether if it acquir'd its Virtues so, there were upon the Impregnation any Efferves∣cence? or whether any such Effect succeeded its Mixture with another Liquor?
• 14. Whether there be a Spring of a contrary Nature near it, viz. as to Heat and Cold, as it is observ'd in France.
• 15. Whether an oyly or bituminous inflam∣mable Substance float in it?
• 16. Whether the Seasons of the Year, or Tem∣perature of the Weather alters them? and what Qualities they lose or acquire by such? For after Rain I have observ'd such Waters incapable of turning a Tincture of Galls black: But as to its Medicinal Virtues, I have found that Rain after long Droughts, hath rather increas'd than dimi∣nish'd their Strength, by dissolving and diluting those Salts, which were fix'd in the Earth for want of a Vehicle; but if the Waters be weak, and the Rain much, those Salts being the more diluted, render the Waters less Effe∣ctual.

• 17. Whether the Qualities of the Waters may be Chymically and Mechanically discover'd? as also of what Colour and Weight, and with what Menstruums their Salts may be mix'd? and likewise what Substances they will yield when expos'd to different Degrees of Fire, and what other Chimical Tryals those as well as the Caput Mortuum may undergo?

CHAP. X. Containing Titles for the Natural History of Mineral Waters when drawn out of their Receptacles.

* 1.521. WHether the Mineral Water propos'd be actually Hot or Cold? From whence we may judge from what Depth those Waters rose? and whether they were impreg∣nated with a Salt-Peter or Sal-Armoniack in their Ascent? And the several Degrees of Heat or Cold may be either try'd by immerging a Ther∣moscope, or by trying whether they will Coagu∣late Oyl of Aniseeds or melt Butter?

2. Of the specifick Gravity; which, being compared with that of common Water, will shew what Quantity of Mineral Substance the Water hath dissolv'd in it; and whether Me∣talline or more Volatile, as it is heavier or ligh∣ter; where we are to observe, that Mineral Waters are sometimes lighter than common Wa∣ter; partly, because they are impregnated with

Volatile Parts; and partly, because they are void of Saline Parts, which makes common Water something heavier. But to discover the different Weight of several Mineral Waters, I caus'd a Glass-Viol with a flat Bottom and a long Neck, three Inches long, to be blown, which was so light, as to weigh but ʒvi + 42 Grains; tho' it was capable of containing ℥iij ss and 43 Grains of Water; which made it more proper for a Nice Ballance, by which I found the following Mineral Waters to differ thus in Weight.

Waters	Ounces	Drachms	Grains
Common	3	4	43
Common distill'd	3	4	41
Acton	3	4	48 ½
Epsom	3	4	51
Dulwich	3	4	54
Staton	3	4	55
Barnet	3	4	52
North-Hall	3	4	50
German-Spaw	3	4	40
Tunbridge	3	4	38
Islington, from the Musick-House.	3	4	36
Islington, from the Vault with Steps.	3	4	39
Islington, from the Cellar.	3	4	39

3. Of their different Degrees of Transpa∣rency or Opacity.

4. Whether without being exposed to the Air, it will afford a Pracipitate. By which Ob∣servation

the different Soils through which they pass, will not only be discover'd, but hence we may learn to distinguish such from the true Ca∣put Mortuum of the Water. German Spaw Wa∣ter yielded a good Quantity of yellowish Oker. N. B. the Water so try'd must not be expos'd to the Air, for if it be the Air will precipitate a considerable Quantity of Matter in most Waters.

5. What Microscopes can discover in Mineral Waters?

N. B. those moving Corpuscles discernible in a Solution of Pepper, &c. in Water, are Animalcula, and not Portions of Inanimate Mat∣ter, which swim up and down such Liquors; which is apparent if those little Animals be touch'd with Spirit of Salt, for being kill'd by it, they move much more slowly.

6. Whether there be any variety of Colours in several Mineral Waters?

7. Of their different Odours. These are to be perceiv'd at the Spring-Heads, where not only a Bituminous and Sulphurious Smell may easily be perceiv'd; but I am inform'd, that there is a Mineral Spring in France which hath a mani∣fest vinous Odour.

8. Concerning the different Tastes of Mineral Waters.

9. Whether taking it up, or keeping it stop'd or unstop'd? or whether freezing or thawing it will alter the Colour, Smell or Transparency of it?

For tho' some Waters retain their Purgative Virtue a good while; yet, I have observ'd an Exhalation of some fugitive Parts from those which are lighter than Water, and abound with

Spirituous Parts; so that, tho' they were car∣ry'd but a little way from the Fountain, they pre∣sently lost their Power of turning a Tincture of Galls into a Purple, and instead of that, turn'd it red; and even the Strongest Waters, if kept un∣stopp'd, or not kept close, presently lose that Property.

10. Concerning the different Consistency of such Waters.

11. Whether they be more apt to Expansion and Condensation, or Heat and Coldness, than Common Water?

12. Whether they are apt to Putrify, and how soon, and what Phaenomena they afford?

13. What Alteration in Colours ensues the Mixture of Astringent Juices with them, as also their Mixture with several Juices of the Body.

N. B. in trying of Mineral Waters, it is usual to make use of a Tincture of Galls, without con∣sidering the Alterations which may be made in the Tryal, by an Uncertain Proportion of Galls: Wherefore I usually make use of a settled Propor∣tion, as 5 Grains to an Ounce; tho' Mineral Wa∣ters may be try'd with much more Expedition, and Certainty, by making use of the Powder it self, suspending about three Grains of Powder in an Ounce of the Waters; and I have found by Experience, that so small a Quantity as a Grain, hath given German Spaw-Water a deep Purple Co∣lour. But it is not always necessary to make use of Galls in such Tryals, since Rose Leaves, or the Flowers and Bark of Pomgranates, will have much the same Effect, affording a Cloudy and Blackish Tincture.

And it is further to be noted, That I made it one Part of this Quaere, what Colours would be pro∣duc'd by a Mixture of Mineral Waters with Ani∣mal Juices; because I have observ'd the Root of the Tongue sometimes Blackish upon the taking of Large Doses.

But to return to what I have observ'd concern∣ing the trying of Mineral Waters, by an Infusion of Galls; I not only doubt whether all Martial Wa∣ters will turn a Tincture of Galls black, but whe∣ther all liquors which will, are to be esteem'd Mar∣tial; for I have found that a Mineral of a Diffe∣rent Nature from Steel, would give it a Black Colour; and that a Liquor, which was a Prepa∣ration of Steel, would not; which induc'd me to think, that such a Tincture was rather the Ef∣fect of some Acid Fumes, which had work'd on the Mars, with which those Mineral Waters are Impregnated.

To which it may be added, That I have found, that if a Vitriolate Water be impregnated with Copper, instead of Iron, instead of turning a Tin∣cture of Galls Blackish, it only would render it Muddy and Thick. And I had a sort of white Earth, which I found by Tryals to be Lead, that would turn a Tincture of Galls Blackish, tho' it was altoger void of Martial Parts, and probably would have very bad Effects, if taken inwardly. To which I might further add, That a Tincture of Gold in Aqua fortis, likewise turn'd an Infusion of Galls Black.

And those Observations I have been the willinger to lay down, because, tho' I would not be thought by them to slight the Use of Galls, in such Tryals, yet I would thence

urge them to make such Tryals to be more wari∣ly made.

* 1.53And because it may be of some Use to observe the different Colours exhibited by such Tryals, I shall add, the following Considerations, as Re∣quisite to be thought on by him, who designs to make such Experiments.

1. That he ought to observe the Changes of Colours, made by such Tinctures, in a good Light; which may help a Curious Observer to distinguish what Minerals such Tinctures are impregnated with. 2. It way be of Use to vary the Shades of Colours, produc'd by Mineral Wa∣ters, either by dropping such Waters upon Pa∣per, whose Pores are saturated with Vitriol pow∣der'd, or ting'd with a Decoction of Log-wood: Several Variations in Colours may be also made, by dropping other Medicinal Liquors, either into the Mineral Waters; or the Infusion of Galls, before Mixture, or after. 3. I would recom∣mend, for such Tryals, not only the Parts of Astringent Plants, but also Animal, and espe∣cially Mineral Substances: For, besides the A∣stringents, I have contriv'd a certain Substance, which would not only turn a Vitriol Water im∣pregnated with Iron black; but also One satura∣ted with Copper; a Succedaneum, to which may be made, by adding to Sulphur as it melts over the Fire, and equal Proportion of Salt of Tar∣tar finely powder'd, stirring them till they in∣corporate, and become red: Which Mixture, being put into a Glass Retort, with half it's weight of Sal-Armoniack, dissolv'd in Water; let it be distill'd in Sand, shifting the Receivers as the Liquor drawn off, is ting'd more or

less; so that the strongest may be preserv'd by it self.

And such Tryals as these will be of more use, than those usually made with a bare Tincture of Galls; since there are several Mineral Sub∣stances and other Bodies, which Mineral Waters may be impregnated with, which discover not themselves in an Infusion of Galls: As Sul∣phur or Copper, may be so lock'd up in these Wa∣ters, as not to be perceiv'd, till the Body of the Liquor is open'd by some proper Additament. And even Arsenick it self, may be so disguised, as not to be perceiv'd, when mix'd with the Wa∣ters; yet if Spirit of Urine, or Oyl of Tartar; per Deliquium, be dropp'd into a Solution of it, it presently precipitates in the Form of a white Powder; and so likewise, if a Solution of Subli∣mate be added to it.* 1.54 But to discover, whether Mineral Waters be impregnated with Arsenick or not, I put Dantzick, or English Vitriol into a Solution of it, either of which caus'd a dark precipitate gradually to subside.

14. Whether Spirituous Acids, volatile Al∣kalys, or Lixivial Salts will precipitate such Wa∣ters?

15. The Manner of Extracting Salts from such Waters, and what Quantities may be ex∣tracted? Guesses may be made concerning the Saltness of these Waters, by trying whether they will Lather with Soap? and if not, what Quantity of Curdled Matter they will yield? I have ob∣serv'd that even the lightest Waters will yield a small Quantity of common Salt.

16. How to discover what Acidity is to be found without Evaporation. Having taken a

peculiar Method to try the Acidity of Mineral Waters, by mixing them with an Infusion of Lignum Nephriticum in simple Water, I found, that tho' German Spaw, yielded a small Quan∣tity, yet in that of Action, there was none di∣scernible.

17. What may be observ'd by Distillation in Balnco?

18. What, and whether the same Quantity of Caput Mortuum, be afforded by Evaporation, and Distillation?

19. Whether Mineral Waters will acquire the same Qualities and Texture, by a Reunion of their Caput Mortuum, when distill'd to such a Consistence, in Glass-Vessels exactly luted, which they had before?

20. What Changes, if any, Mineral Waters undergo by being boil'd in Water, in a Glass Hermetically seal'd? From whence might be learn'd whether a Change of Qualities would succeed an Alteration of Texture, without a manifest loss of Parts? And whether an Agita∣tion of Parts, without the Influence of the Air, would precipitate any thing, or deprive it of it's Power to turn a Tincture of Galls Purple?

21. How much the Mineral Waters exceed their Caput Mortuum in Proportien?

22. What Parts are contain'd in the Caput Mortuum, and whether dissoluble in Water?

23. How much the Saline and Terrestrial Parts differ in Proportion?

24. Whether in strong Fires, the Salts be Volatile or Fix'd, and to what Degree?

25. Whether the Salts will Crystallize per se,

or with other Salts, and what's the Figure of the Genuine, or Compounded Crystals?

26. Whether Acid or Alkaline Qualities are most predominant? The Acidity will either appear to the Taste or Smell; or may be disco∣ver'd by turning Syrup of Violets red; as also, by making use of an Infusion of Lignum Nephriticum, which upon a Mixture of Acids loses it's Blue Colour: Their Acidity may likewise be disco∣ver'd by trying, whether they will be precipi∣tated by Alkalys, or ferment with them. And if Alkaly be predominant, it, on the contrary discovers it self by a Lixivial Taste and Smell; and may be discover'd, by turning Syrup of Vio∣lets Green, or precipitating a Solution of Subli∣mate, or Fermenting with Aqua fortis; or lastly, by increasing the Colour of a Tincture of Brasil or Log-wood in Common-water? And tho' we have no such Springs here in England, as afford Alkaline Salts; yet without question, in Egypt such may be found, since their Latron, or the Egy∣ptian Nitre, abounds with a Salt of an Alkaline Nature: and I have obtain'd such an Alkaly, from that Famous Water of Bourbon in France, which would turn Syrup of Violets green, and fer∣ment with Volatile Acids. If such Waters abound with Vitriol, they'll turn an Infusion of Galls black, and Vomit those that drink them; and, if an Alkaly be added, will yield a yellow Pre∣cipitate, upon dropping of Spirit of Ʋrine, or Salt of Tartar into them.

I have not found any of the Waters about Lon∣don, to be impregnated with Vitriol; and I am told, that in France the Mineral Waters are so far from being impregnated with Vitriol, that there is 〈1 page missing〉〈1 page missing〉

a Vitriolate Spring in that Kingdom. As for the Nature of the Salt, which most Mineral Wa∣ters are impregnated with, I think that it is not to be referr'd to any Glass, but is either sui gene∣ris, and a peculiar one, or a Compound Salt, made up of such as the Water is impregnated with, in it's Passage through the Earth; and that Purgative Salts may, by a Change of Texture, be made of Salts not at all Purgative, I the rather be∣lieve, because I have been told by an Ingenious Emperick, That a Salt which I made of Salt of Tar∣tar, and Common Sulphur mix'd together, had a gentle Purging Virtue.

27. In what Menstruums the Caput Mor∣tuum may be dissolv'd? and in what it may not? Whether Volatile or Fixt, and what Qualities it hath in Respect of Colour or Smell?

* 1.55It is to be admir'd, what a great deal of Caput Mortuum some Mineral Waters yield in Compa∣rison of others; since those Waters: which are purely Diuretick have very little, if compared with the Caput Mortuum of Purging Waters: For tho' a pound of Barnet Waters, yielded a Drachm, yet the same weight of Tunbridge afforded but a Grain. And,

It is not a little strange, that so small a Quan∣tity of a Mineral should impregnate so much Water, as I have, by Tryal, found a Grain of Iron Stone did, enabling it to Tincture an Infusion of Galls, deeper than Tunbridge or German Spaw Wa∣ter would. And I have try'd, that half a Grain of Marchasite, dissolv'd in Spirit of Nitre, com∣municated a Tincture to 61440 Parts of Water; tho' Part of that Marchasite was Sulphur, and Part of it Caput Mortuum.

And here it may be seasonable to take notice, That if so small a Portion of a Metalline Sub∣stance would, when grosly dissolv'd, impregnate so large a Quantity of Water; how much more may it, when rais'd in the Form of a Subtile Mi∣neral Fume? and as in such a Form, it may im∣pregnate a larger Quantity of Water, so will it be more apt to fly away, when expos'd to the Air. And that Vitriol may probably rise in the Form of a Vapour, without losing it's Qualities, is evident in Sublimate, which consists of Mer∣cury, chang'd by an Addition of Salt and Vitriol; for some Vitriolick Parts being carry'd up in the Preparation, turn Opacous upon an Affusion of Spirit of Sulphur.

But further, to make it evident, that the Par∣ticles of Iron may be considerably expanded, I dropp'd four Drops of a Vitriolick Liquor, made use of in Copperas-works, into twelve Ounces and a half of Water, and found, that it so much im∣pregnated 1500 times it's Proportion of Com∣mon Waters, as to make it strong enough to turn a Tincture of Galls Purple, tho' by Evaporation we found that 3 Parts of 4 of that Liquor were Water.

28. What Alterations the Earthy Parts of Mineral Waters undergo by Ignition; and whe∣ther they may be Vitrify'd per se? as also what Colours they impart to Venice Glass, if mix'd with the Powder before Fluxion?

29. Of what use they are in Baking, Brewing, Tanning, or Dying of Colours, &c.

30. How many ways they may be made Artificially, and with what Proportion of In∣gredients?

CHAP. XI. Titles for the Natural History of Mineral-Waters, consider'd as a Medicine.

IT may be worth Observing, in order to a more Compleat Natural History of Mineral-Waters, what Constitutions they agree with, and in what Distempers they are Proper or Dan∣gerous: What Sensible Operations they have; and whether their Effects be alter'd by Drink∣ing them Hot or Cold; at the Well, or at a Di∣stance from it: Whether Exercise, or the Warmth of a Bed, promotes their Operation: Whether they have any Occult Qualities.

It may likewise be requisite to observe; What good Effects may succeed a due Preparation of the Body that drinks them, and what Advantage it may be to drop some Strengthening Sto∣machick into the First Dose: What Quantity is enough for the First Dose, and how it must be vary'd: How long they may be Drunk, and whether constantly, or with Intervals; whether Purging sometimes may contribute to their good Effects: What Regimen in the Six Non-Naturals is to be observ'd, whilst they are a-taking: Which are the Signs that denote the kindly Ope∣rations of them; or their future ill Effects. What ill Accidents attend the taking of them, and how they may be Remedy'd, or Prevented. Whether it be proper to Purge after the Taking of them.

What Effects they will have by Mixing other Liquors with them; or, by Boiling Meat in them; Whether a Salt extracted will be of Equal Effect, when Diluted in Fresh Water. What External Effects they will have, and of what use their Se∣diment is when Externally apply'd: What Ef∣fects they will have on Dogs, if injected into their Veins, or if they be kept with such for constant Drink.

CHAP. XII. Of the Natural and Preternatural States of Bodies; especially the Air.

IT is the General Consent of most Men, that the Determinate States of Bodies are not on∣ly first fram'd by what they call Nature; but that they are likewise preserv'd in those States, by the Superintendency of that Power; and that whenever they lose that State, they are said to be put into a Preternatural One. But if we consider, that such Changes proceed from Natu∣ral Causes, and that those New States depend on the like Catholick Agents,* 1.56 and the Establish'd Laws of Nature; it will appear, That the Di∣stinction Men usually make betwixt the Natural and Preternatural.▪ States of Bodies, is but ill-grounded; and that Preternatural, is only a Re∣lative Term, intimating that that Body hath un∣dergone a Change, either by the Operation of some unheeded or more noted Agent. For

Matter being altogether void of Sense and Per∣ception, and not affecting one State more than another, the Changes it undergoes, depend on the Alteration of it's Textures, and New Po∣sition of it's Parts, alter'd afresh, by that Agent, which such a Body was last expos'd to. As a piece of Wax, is put into a New Form, by the last Impression, made by another Body upon it, without affecting one Form more than another it self.

* 1.57And that the States of some Bodies, which are said to be Preternatural, as truly depend on Natural Causes, and the Establish'd Laws of Nature as others, is evident in Ice and Wa∣ter: In which Bodies, the Forms of each de∣pend upon the Effects of External Agents; for, tho' in these Hotter Climates Water is Esteem'd a Natural, and Ice a Preternatural State of that Substance; yet I am inform'd, that in Siberia, a Province belonging to a Russian Emperour, Water is froze most part of the Year; and at a small▪ Depth, from the Surface of the Earth, the Soil is froze throughout; where Ice is look'd upon to be the Natural, and the Alterations made by a Thaw, and the Influence of the Ex∣ternal Temperature of the Air, and the Sun Beams, are esteem'd Preternatural States of Bo∣dies. And further, tho' Butter in our Clime be sold in a consistent Form, and when it is melted, is look'd upon to be in a Preterna∣tural State; yet I am inform'd, that amongst the Europeans it is fluid, and is sold by Mea∣sure, and not by Weight, as here in England. And it is further observ'd, That several Sub∣stances, as Rosin of Jalap, Gum Lacca, and even

Aloes it self, are considerablely softened in their Consistence, by the Temperature of the Air, and the Force of External Heat, whilst they pass under the Torrid Zone; so that I am told, that the former of the aforemention'd Drugs was melted into a sort of Balsam, whilst it con∣tinued in Africa, but when it was brought to Spain, it put on a Consistent Form again: And tho' Aloes was soft whilst carry'd through America, and those hotter Climates, yet when it approach'd our Climate, it presently became hard.

But to bring further Instances concerning the Natural and Preternatural States of Bodies, I shall observe, That according the Receiv'd Notion of Natural and Preternatural States, it is very difficult to determine the Natu∣ral State of the Air; for, not to insist on the different Temperature of the Air, as to Heat and Cold, in different Climes; It may be de∣manded, Since Heat and Cold, rarifie and ex∣pand the Air, what is to be esteem'd the Na∣tural State of it, in Reference to Rarity and Density? And it is no less Questionable, what Place is most fit to determine it's Natural State, since the State of it is not only different in several Countries; but in those Places at diffe∣rent Times: And that the Changes, as to the Density or Rarity of the Air, are very fre∣quent, appears by the several Degrees of the Atmosphere's Gravity, evident in the Torrecel∣lian Experiments, hereafter to be deliver'd.

* 1.58But further: Except the States of the Air be said to be Preternatural, only in a Relative Sense, with respect to the State it was in, before it

underwent the last Change, it is not impos∣sible to make it out, That the Air is always in a Preternatural, because always in a Forced State; the Lower Parts of the Air being con∣stantly press'd upon, and by the Weight of Incumbent Air, kept from expanding it self; but if the further it recedes from a forc'd State, the nearer it approaches to a Natural One, then the Force of the Fire must by Rarifying it, contribute to the Destroying of it's Preterna∣tural State; and by the same Reason the Air contained in our Pneumatical Receiver, when Part of it is drawn out, must approach to a Natural State, the Remaining Part having fur∣ther Liberty to expand it self.

To conclude this Chapter: From what hath been said, it appears, That that is truly the Na∣tural State of a Body, in which it is preserv'd by a Natural Concourse of External Agents: And likewise from what hath been said, we may infer, That it is a common Error, That nothing Violent is Durable; since it is evident, that the Atmosphere we live in, is always in a Forc'd or Compress'd State.

CHAP. XIII. The Description of the Pneumatick Engin, and it's Use. Physico-Mechanical Expe∣riments touching the Air, in a Letter to the Right Honourable Charles, Lord Vis∣count of Dangarvan.

My Dear Lord,

PErceiving that several of the Virtuosi at Paris, intent in Examining, how far the Air was concern'd in hindering the descent of Quick∣silver, in the Torrecellian Experiment, concern∣ing a Vacuum; I thought it seasonable to pro∣mote that Experiment; and to acquaint Your Lordship with my Attempts on that Subject, which may afford some Hints at least towards the Advancement of that Philosophy.

A Subject which I the rather make Choice of; because, the Air being of so general use in Re∣spiration, and, by it's almost Perpetual Conti∣guity, as well to our own Bodies, as those we are here concern'd with, having Considerable Effects, in Producing those Various Diseases in∣cident to Crazy Bodies, upon Changes of Wea∣ther, a Discovery of it's Nature may be of Mo∣ment; and likewise, because it may shew us how far it concurs in Exhibiting several other Pha∣nomena.

But before I present Your Lordship with the Experiments, it will not be improper to give

Your Lordship an Account of the Engine con∣cern'd in the making of them.

* 1.59It consists then of two Principal Parts; a Glass Vessel, and a Pump to suck out the Air contain'd in it. The First of which is a Glass, furnish'd with a Hole at the Top, to which a Cover is ad∣apted, and also a Stop-Cock, fitted to the Ex∣tremity of it's Neck below; the Cavity of it being large enough to contain about 60 lib. of Water, allowing ʒxvi. to each Pound.

The Diameter (B C) of the Top of the Vessel (A) is about four Inches, which is en∣compassed with a Lip, almost an Inch in Height; the Use of which is for the Cover to rest on; which is describ'd in the second Figure, where (D E) denotes a brazen Ring, which is to co∣ver and to be closely cemented on the Lip (B C) of the first Figure. To the Internal Orifice of this Ring is adapted a Glass Stopple, so exactly, as to prevent any considerable Access of exter∣nal Air: In the midst of this Cover there is a Hole (H I) about half an Inch Diameter in∣circl'd with a Ring or Socket, to which is a∣dapted a brazen Stopple (K) so exquisitely, that it may be turn'd round without admitting in the least Air. Through the lower end of it there is a little Hole (8) made for the Passage of a String (8, 9, 10) which is likewise to pass through a small brazen Ring (L) fix'd to the bottom of the Stopple (F G) the use of which String is to move what is contain'd in the exhausted Vessel, when stop'd.

That the Stop-cock (N) in the first Figure, might more exactly exclude the Air, a thin Plate of Tin (M, T, V, W) was soder'd on

the Shank of the Cock (X) of a Length pro∣portionable to the Neck of the Receiver, which was cemented, with a Cement made of Pitch, Rosin and Wood-ashes, pour'd hot into the Ca∣vity of the Plate; and to prevent the Cement from running into the Orifice (Z) of the Shank (X) it was stopp'd with a Cork, to which was fix'd a String, that it might be drawn out of the upper Orifice of the Receiver, and then the Neck of the Glass Receiver being press'd moderately hot into the Cement, it fill'd the Interstices betwixt the tin Plate and the Re∣ceiver, and also, betwixt the Receiver and the Shank of the Cock.

The lower Part to be describ'd is made up of an Air-pump, supported by a Frame of Wood with three Legs (111) so contriv'd, that, for the freer Motion of the Hand, on one side it may stand perpendicular; a-cross the midst of the Frame, a Piece of Board is nail'd (222) to which the Pump is fix'd.

The Pump is made up of four Parts, viz. An exact and strong Cylinder, endued with a Cavity about three Inches cross; to which a Sucker (4455) is adapted, made up of two Parts; one of which (44) being not so large in Diameter, as the Cavity of the Cylinder, a thick Piece of tann'd Leather is nailed on it, by the Addition of which, it closes so exactly to the Cylinder, that the Air cannot insinuate; The other Part being a thick Plate of Iron (55) is firmly joyn'd to the middle of the former Part; it is a little longer than the Cylinder; one Edge of it being smooth, and the other indented,

to the Interstices of which the Teeth of a small Jaton Nut (α β) are to be adapted, which is fix'd by two Staples (22) to the under-side of the Board nail'd transverse (222;) on which the Cylinder resting, it is turn'd by the Manu∣brium (7.) The last Part of the Pump is the Valve (R) being a Hole at the Top of the Cy∣linder, which is taper towards the Cavity: To this is fitted a brass Peg, to be put in or taken out, as Occasion requires.

The Engine being thus delineated, the Stop-Cock must be well oyl'd with Sallad Oyl, to stop the Intervals of the Internal Surfaces of its Parts, and also, that it may with less diffi∣culty turn the Key (S) at Pleasure; for the like Reasons the Sucker as well as the Valve is to be oyl'd also. And here it is as much strange as to be admir'd, That when Oyl or Water separate, have fail'd in effecting our Design, a Mixture of both hath prov'd effectual. Lastly, That the Ingress of Air betwixt the brazen Cover and the Ring, may be likewise prevented; it will be convenient to plaister the Edges with the for∣mer Cement, laid on with a hot Iron, that it may the better fill the little Cavities.

Things being thus ordered, That no Air may remain in the Cylinder, the Handle is to be turn'd till the Sucker rises to the Top of it; and then, the Valve being shut, it is to be drawn down to the bottom; by which Means, the Air being driven out of the Cylinder, and a Succes∣sion from without being prevented, the Cavity of the Cylinder must be emptied of Air, so that the Turn-cock beng turn'd so as to afford a Passage betwixt the Receiver and Cylinder,

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Part of the Air before lodg'd in the Receiver will be drawn down into the Cylinder, which, by turning back the Key,* 1.60 being prevented from flying back into the Receiver, may, by open∣ing the Valve, and winding up the Sucker, be forc'd into the open Air; and so, by reiterated Exsuctions of the Air out of the Receiver, and Expulsions of it again out of the Cylinder, it may be exhausted as the Nature of the Experi∣ment requires.

Having thus given your Lordship a Descrip∣tion of the Engine, and Cautions for the Pre∣vention of the Ingress of Air, necessary in some more curious Experiment; I shall in short ac∣quaint your Lordship, That the Experiments I proceed to entertain your Lordship with, are such, as require not such Exactness in the fore∣mentioned Cautions, provided the Pump be well plied and the Crannies not considera∣ble.

EXPERIMENT I. The Manner of Pumping out the Air. A Digres∣sion concerning the Spring and Elasticity of the Air, in Order to a more clear Apprehension of subsequent Experiments.

FROM what hath been deliver'd it appears, that, the Sucker being wound up, and, upon stopping the Valve and turning the Key, drawn down again, the Air will be equally ex∣panded both in the Receiver and Sucker; and upon returning the Key, and opening the Valve,

near a Cylinder full of Air will be expell'd; but the Receiver, by reiterated Excursions, being more and more exhausted, less proportionably is forc'd out; so that at the last, before you need to open the Valve, the Sucker will rise almost to the Top of the Cylinder; and if, when it is so exhausted, you let go the Pump, and the Valve be stop'd, the Sucker, meerly by the Force of external Air, overpowering that more rarify'd Air within, will be forc'd up to the Top of the Cylinder; where we may ob∣serve, That as the Sucker is press'd higher by external Air, so it is an Argument of the Re∣ceiver's being more or less exhausted; the Air in the Sucker being accordingly more or less able to resist the external, as it varies in Quan∣tity: We may observe also, That whilst the Receiver retains any considerable Quantity of Air, there is a brisk Noise upon turning the Key.

* 1.61But to render these Experiments more intelli∣ble, I shall take Notice to your Lordship of a Notion, which may explicate them; which is, That the Air consists of certain springy Parti∣cles, which, being bent and press'd together by incumbent Bodies, always endeavour to remove that Pressure, and to dilate themselves; which Notion may be confirmed, by considering, that the Air consisting of Parts incumbent on one another, the uppermost, by their weight, must needs compress the lower; which compressed Parts must consequently have a Power of self-Di∣lation: So when a Fleece of Wool compressed, upon the Removal of that Pressure again ex∣pands it self, the Springiness of the Air may like∣wise

be explicated by supposing with the Inge∣nious Des Cartes, that the Air is a Congeries of flexible Particles, of various sizes and very ir∣regular Figures, raised by the Heat of the Sun, and swimming in that Matter, which encompasses the Earth; which being, by that Aether that floats about them, kept separate and in a violent Agi∣tation, acquire that Springiness which they would lose in some measure by being compres∣sed.

By both these ways the Springiness of the Air may be explained; yet by which with most Rea∣son I shall not now dispute, being not so much concerned about the adequate Cause of that Sprin∣giness, as to manifest, that it hath a Springiness, in order to shew the Effects of it; for I am not sa∣tisfyed, whether either so far explains it's Na∣ture, as to make it intelligible.

But in opposition to this Notion it may be al∣ledged, that tho it were granted, that the Air is made up of springy Particles; yet, it would only account for the Expansion, and the Dilatati∣on of the Springs of the Air, when apparently compressed in Wind Guns and other Pneumati∣cal Engines; whereas from these Experiments it does not appear, that there was any Compres∣sion before the Air was included in those Guns. To remove this Difficulty, there are several Ex∣periments which prove, that our Atmosphere is not light, but heavy, in respect of some Bodies, one of which I shall mention here, which is this, that a Lamb's Bladder dryed, whose Cavity con∣tain'd two thirds of a Pint, being press'd toge∣ther, and counterpoised in a very nice Balance, and being prick'd, upon the avolition of the

Air contain'd in it, lost a Grain and an eighth Part of what it weigh'd before; from whence, if we may conceive, that it hath weight, it fol∣lows, that a Column of Air of many Miles high leaning on those below, is enough to compress and bend their Springs; as when Wool is heaped to a considerable height, that which lyes under is compressed by that which lyes upon it; and if upon a Parcel of Air, so large a Quantity lyes, no wonder, that upon the Removal of that Pres∣sure, it powerfully expands.

As for the Objection, that Water varies not in it's Weight in the lower from the upper Part, it may be answered, that the difference betwixt Air and Water is very considerable; the last not being capable of Compression; whereas Air is. To which may be added the Experiment tryed by Monsieur Pascal (the Son) at the foot, the midle and top of that high Mountain (in Avergne) cal∣led Le Puy de Domme,* 1.62 where the Mercury subsi∣ded above three Inches more at the Top than the bottom; the Reason of which is, that the Air less vigorously pressed against the Quicksilver at the Top, and so was less capable of bearing it up.

And if it be objected against what hath been proposed, that if it were so compressed, it would not be so ready to yield to the slight Force of Flyes, and even Feathers, it may be answered, that as a Piece of Wool squeezed together, makes a manifest Resistance to the Pressure of the Hand; so the Air does to those Bodies, tho it's Resistance is not strong enough to overpower their Motion, the Parts of it being in a continual Disposition to yield to solid Bodies, upon the Account of it's

Fluidity, and the perpetual Motion of it's Parts, occasioned by their continual Endeavours to ex∣pand and unfold themselves.

EXPERIMENT II. Of the Pressure of the Air against the Sides of the Bodies it encompasses. The Pressure of the Air in∣cluded within an Ambient Body explain'd.

* 1.63IF, when the Air is almost drawn out of the Receiver, one endeavours to lift up the Brass Key which is plac'd in the middle of the Brass Cover; it will be as difficult to raise it, as if a considerable Weight were ty'd to it; for the Spring of the Air included in the Receiver being weaken'd, and not able to bear up strong enough against the bottom of the Stopple, as powerfully as before; whoever lifts up the Stop∣ple, must likewise bear up the whole Pillar of External Air, which presses upon the top of the Stopple: But if the Air be gradually permitted to get into the Receiver, the Internal Air being more compress'd, and its Spring encreas'd, it bears up against the Stopple more powerfully, and the Pressure of the Internal and External Air being brought nearer to an Aequilibrium, the Stopple may proportionably be lifted up with less difficulty; till at length, the whole Cavity of the Receiver being fill'd with Air, it may ea∣sily be taken up.

But it's thought strange by some, how the Pressure of the Included, can be any ways pro∣portionable to the Pressure of the External Air; since it is so encompass'd by the sides of

the Receiver, that those Pillars of Air, which would press upon it, if open to the Air, are only icnumbent on the External Superficies of the Receiver; but to unfold this Difficulty,* 1.64 we may consider, That as a piece of Wool•• squeezed in ones Hand, and so enclos'd in a Box, is kept from expanding equally by the sides of the Box, as if it remain'd in ones Hand; so the Air com∣press'd by the Incumbent Asmosphere, and con∣veigh'd in that compress'd State, into the Re∣ceiver, is equally kept from expanding it self by the sides of the Receiver, as if it were still squeez'd together by the weight of the Atmosphere: And if it should further be objected, that if the Air in∣cluded in the Receiver were so confin'd by the sides of it, it's continual Endeavour to expand would break the Glass: It may easily be an∣swer'd, that the expansive Force of the Inter∣nal Air, is counterpois'd by the Compressure of the External, and consequently there being an equal Pressure on both sides, it is preserv'd en∣tire; for a like Reason those slender Bubbles, which Boys usually blow up with Soap and Wa∣ter, continue whole for a good while, the In∣ternal and External Air, being compress'd to a just Aequilibrium.

EXPERIMENT II. Concerning the Force requisite to draw down the Sucker: The Opinion of a Modern Naturalist examin'd.

* 1.65THough the Sucker may be easily drawn down, by the help of the Manubrium▪ yet without that it will require a Force capable

of raising so much of the Atmosphere as presses upon it: The Reason of which is evident, from Mercury suspended in a Tube; for tho' the Weight of the Atmosphere is able to ballance and keep it up to twenty five Digits; yet if the suspended Mercury exceeds that height, it pre∣sently over-powers the Pressure of the incum∣bent Atmosphere, and subsides to its just height. And as from hence we may learn, why it is so difficult to draw down the Sucker; so it like∣wise teaches us, for what Reasons the Sucker, when so violently forced down, upon a Relaxa∣tion of that Force rises up again; for the Spring of the Air included being weak, it must conse∣quently be buoy'd up by the Pressure of the Ex∣ternal, till that which is contain'd in the Re∣ceiver be equally compress'd, so as to be able to resist the Pressure of the Atmosphere. There is one Thing more remarkable in this Experi∣ment, which is, that if the Valve be stopped close, when the Sucker is rais'd to the Top of the Cylinder, it finds an equal Resistance by the Pressure of the Atmosphere when first drawn, as when nearer the Bottom of the Cylinder; from whence we may gather, that what an Eminent Modern Naturalist delivers concerning the Rea∣son of the violent Ingress of exhausted Air, viz. That it is encreas'd by the Addition of that Force, which it receives from the Air sucked out, is a mi∣stake; for were it so, it would be more difficult to draw down the Sucker, when it is further from the Receiver, a greater quantity of Air being exhausted. But from what hath been premis'd in the first Experiment, it is evident, that the weaken'd Pressure of the Internal Air,

is sufficient to account for the more violent In∣gress of the External.

EXPERIMENT IV. Concerning the Swelling of a Bladder, The Opi∣nion of a Learned Author Examin'd.

* 1.66HAving conveigh'd into the Receiver a Lamb's Bladder, well dry'd and limber, and half full of Air, the Cover being luted on, and the Pump set on work; we observ'd, that as the Air in the Receiver was gradually exhausted, that in the Bladder was accordingly expanded, till the Receiver being near fully exhausted, the Bladder seem'd very much distended, with the included Air. And to confirm our Guess, that the Ex∣pansion of the Air in the Bladder, proceeded partly from the weaken'd Pressure of the am∣bient Ai, rwe gradually left in the external Air, and found, that the Bladder by degrees subsided till it became as empty as before: But one thing Remarkable in this Experiment was, that the more the Receiver was exhausted, the more sensibly the Bladder was distended.

And lest in this Experiment it should be doubted, whether the Distention of the Bladder did not rather proceed from the Fibers of the Bladder, returning of their own accord, to their natural Extension upon the removal of the ex∣ternal Air, we put in two empty Bladders a∣long with the former, and found them very lit∣tle extended upon the Exsuction of the Air. And the like Phaenomena were afforded, by re∣peating the Experiment with a Bladder, which

was half empty, and half fill'd with Air, the empty Part being parted from that which con∣tain'd the Air, by a Ligature.

EXPERIMENT V. Concerning a Bladder which burst in the Re∣ceiver, and another by Heat.

* 1.67HAving put a Bladder moderately Blown into the Receiver, before the whole Air was drawn out, the Air presently expanded and broke the Bladder with a considerable Crack; and tho this Experiment frequently succeeds, yet if the Bladder be one that is too dry, it is hard to tie it so fast, but that some of the included Air will get out, and so frustrate the Tryal. But to be fully inform'd whether the Air is out or not, we may be satisfi'd, by admitting Air afresh into the Receiver, which will, if the mention'd Acci∣dent happens, compress the Bladder more than when it was first put in. But it is not only possible, that the Air should expand it self so powerfully in an exhausted Receiver; but if a Bladder well blown, be brought near a good sire, the included Air will burst the Bladder with a considerable Noise.

EXPERIMENT VI.

* 1.68TO try how much the Air was capable of being expanded, we fix'd the Neck of a wet Lamb's Bladder to the Neck of a Viol; which being conveigh'd into the Pneumatical Receiver, upon the Exsuction of the Air, we observ'd, that

the Air which was contain'd in the Cavity of the Viol was so far expanded, that tho' the Viol was able to contain above five Drachms of Wa∣ter, if filled and distended the empty Bladder, which was large enough to hold five Ounces and half a Drachm. In which Experiment, the ex∣panded Air possessed nine times as much space as it did before Expansion.

But to measure the Air's Expansion more nicely, we fix'd a Glass Bubble to one end of a Cylindrical Pipe, hermetically sealed; the Di∣ameter of whose Bore was about a quarter of an Inch; and having pasted a Piece of Parch∣ment upon the outside of the Tube, which was divided into twenty six equal Parts, and mark'd with black Lines, we fill'd the Cylinder almost full of Water, so that, after a few Tryals, by inverting the Cylinder, and stopping the open End with one's Finger, we could perceive, that as much Air might be permitted to rise up to the Bubble, as was equal in Extension to the Breadth of one of those twenty six Divisions; When this was done we fitted the open end of the Cylinder to a Glass Viol, which was fill'd with Water to the Height of half an Inch; all which being put together into a Pneumatical Re∣ceiver, after a few Exsuctions, the included Air was so much expanded, as to extend it self to the Surface of the Water; in which Expe∣riment the expanded Air took up thirty one times as much Space as before.

And this Experiment being repeated in a Cy∣linder, which afforded a larger space for the Air's Expansion, it took up above sixty times the space it did before. And repeating the like Ex∣periment

with a Glass Pipe thirty Inches long (part of it having a Hole in the Cover to stand out through) by weighing the Water in a nice Pair of Scales together with the Pipe, first with the Bubble of Air included, and after when the Tube was wholly filled with Water, we found, That the Air which possessed but the Space of one Grain of Water had been expanded, in the exhausted Receiver so much by its own 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉, as to take up 152 times its Space before Extension.

And since Marcennus affirms, That the Air may be so expanded by Heat, as to take up seventy times its Space, I conveyed a Cylinder of the former Magnitude into the Receiver, and found, That upon the Exsuction of the Air in the Receiver, that in the Cylinder descended down almost to the bottom of it, the lower Surface of it being very convex, and seeming several times to knock upon, and re∣bound from the bottom of the Viol; which was an Argument of the expansive Force of the Air; since the Water it depressed, upon the drawing out of the Air, was much below the Surface of the Water contain'd in the Viol.

EXPERIMENT VII. What Figure best resists the Pressure of the AIR.

HAVING got a thin Glass Bubble, which was large enough to hold about five Oun∣ces of Water, to which was fix'd a slender Neck, about the Bigness of a Swan's Quill, we moderately exhausted the Air out of the Re∣ceiver, and then taking it out of the Pump, we

joyn'd the Neck of the Bubble to the lower Orifice of the Receiver, stopping the Crannies with melted Plaster to prevent the Ingress of the Air; and tho' the Glass was as thin as Paper, yet upon turning the Key of the Stop-Cock, and giving the Air included in the Bubble Liberty to expand, the Bubble sustained the Pressure of the whole Atmosphere, without being broke.

EXPERIMENT VIII.

* 1.69WE took a Glass Alembick, which was large enough to hold about Three Pints, represented by the Seventh Figure; The Rostrum (E) being hermetically closed: In the Top of the Rostrum was a Hole, into which, one of the shanks of a Stop-Cock of an ordinary size was cemen∣ted, the other being fixed with Cement in the upper Part of the Pump; which being done, and the upper Orifice of the Alembick being cove∣red close with a Plate of Lead exactly adapted to it, upon drawing the Air out of the Receiver the Glass presently cracked; which Crack is re∣presented by the Line (a, b) and this Flaw ex∣tended it self further accordingly as the Air was more exhausted, yet this Glass Vessel was near twenty times thicker than the Bubble.

And that the Figure of the former Glass ena∣bled it so much better to sustain the Atmosphere, was further confirmed by suspending one of the Bubbles hermetically sealed in the Receiver, which so strongly resisted the Expansion of the Air contained in it, as to continue whole, when the Receiver was exhausted.

EXPERIMENT IX. A Confirmation of the former Experiment: An Ex∣periment to shew that these Phaenomena exhibited in Vacuo Boyliano proceed not from a fuga Va∣cui, &c.

* 1.70HAving put the end of a slender Glass Pipe into a Viol, which was large enough to contain four Ounces of Water, and fixed it to the Neck of the Viol with a Cement of Rosin and Pitch, so that the end of the Pipe almost touched the bottom of the Viol, as in Fig. 6, this Viol was conveighed into a small Recei∣ver, as much Water being put into it, as wrought a little above the bottom of the Cylin∣der; the upper End of the Pipe being most of it without the Vessel, a Hole having been purpose∣ly made for it in the Top of the Receiver: The Event of which Tryal was, that upon drawing the Air out of the Pump, the Weight of the At∣mosphere internally pressing into the Pipe, and the Spring of the Air within the Receiver, not equally pressing against the sides of the Bottle, which were exposed to it, a Piece of the Bottle burst out of the side of it, with such a Force as to crack the Receiver in several Places; and having reiterated the Experiment with a round Glass Bubble, the Leaden Cover of the Receiver was not only de∣pressed, by the Weight of the Atmosphere, so as to thrust out one side of the Receiver, but the Glass Bubble was cracked into Pieces with such violence, as to tear a Bladder, which it was en∣compassed with to keep it from breaking the Re∣ceiver, in several Places.

Before I proceed to the next Experiment, it may be requisite to advertise, That though the larger Receivers are apt, upon some Tryals, to crack; yet, they are not rendered altoge∣ther useless, since when the Air begins to be exhausted, the ambient Atmosphere compresses the Lips of the Glass closer together. But if the Crack be considerable, it may be cemented with a Plaster made of Quick-lime and Scra∣pings of Cheese ground together very finely in a Mortar, and made into a Paste with a little Wa∣ter, which being spread upon a Cloath about three Inches broad, must be apply'd to the Crack.

EXPERIMENT X.

* 1.71HAVING suspended a Tallow Candle in our Receiver, we found, That upon an Exsuction of the Air, it was presently extin∣guish'd; but another being suspended there without pumping the Air out, it burn'd a little longer, the Flame of both before they went out gradually contracting and ascending almost to the Top of the Wieck with a blue Flame. In which Experiments it was observable, that when the Air was drawn out, the Wieck was presently extinguish'd, emitting very faint Ef∣fluviums, which rose a little Height, and dis∣pers'd themselves in the Receiver very faintly; whereas when the Air remain'd in the Vessel, the Smoak ascended in a. Cylindrical Stream, very briskly and recoyl'd from the Cover. To try what difference there would be in the Phae∣nomena

exhibited by a Candle made of Virgin's Wax, and the former, I suspended several small ones, stuck together, and found, that they would be immediately extinguish'd before the Cover could be cemented on; but having let down one of them alone, we observ'd, that upon the Evacuation of the Air, it continu'd to burn about a Minute; but if the Air was not pump'd out, the Flame continu'd more vivid and lasting: And, as in the Former Experiment, the Flame gradually rose to the Top of the Wieck; so in the Latter, it was depress'd nearer the Bottom, before it was extinguish'd.

EXPERIMENT XI. Concerning the Burning of Coals, and the Continu∣ance of the Heat of a piece of Iron in Vacuo Boyliano.

HAving suspended a Screw made of Wire in the Receiver, such as Fig. 10. represents, it being first fill'd to the height of five Inches, with live Wood-coals; upon the first Exsuction made by the Pump, they grew dim, and the Pump being ply'd for three Minutes, they were quite depriv'd of their red Colour, and seem'd extinct; but when they were taken out of the Re∣ceiver, they were re-kindled again; and being let down into the Receiver afresh, without Pum∣ping out the Air, they continu'd red for a Mi∣nute longer than before; but a like quantity of Live-coals, continued to burn half an Hour, in the open Air.

But a piece of Red-hot Iron, being suspended in the same Wire, upon an Exsuction of the Air, it seem'd not to be sensibly alter'd; but conti∣nu'd red for 4. Minutes; neither was it alter'd by re-admitting the Air into the Receiver, tho' Fumes, which were rais'd from some Wax, which stuck to the Wire, were much more expan∣ded, when the Air was pump'd out, than up∣on it's re-ingress. But one thing observable, was, that whether the Air was suck'd out, or not, the sides of the Receiver were considerably heated by the Effluvia trasmitted from the Iron.

EXPERIMENT XII.

* 1.72HAving suspended a lighted Match in the Receiver, it presently fill'd the whole Ca∣vity with Smoak; which, together with Air, being pump'd out, we could discern the Match to burn still more languid, till at the last it seem'd to be totally extinguish'd; yet some time after, upon a fresh ingress of Air, it renew'd it's Fire, being blown up a-fresh by the Access of that Aery Body.

EXPERIMENT XIII

* 1.73HAving suspended a lighted piece of Match, together with a Bladder, to try whether the Smoak would hinder the Distention of the Bladder, as also whether the Light of the Match would be put out by it's own Smoak; I ob∣serv'd, that it afforded the same Phaenomena men∣tion'd in the foregoing Experiment, except that after Successive Re-admissions of the Air, it be∣ing

excluded for some time, the Fire was totally extinguish'd.

Besides which, the following Phaenomena were to be observ'd: First, That upon the turning of the Stop-Cock, the Cavity seem'd immediately darken'd, as if it proceeded from a Change of the Position of the Parts of the Smoak. Second∣ly, That a kind of Halo, consisting of some Ex∣halations hover'd about the Flame. And Lastly, It was observ'd, that the Fumes did not in the least obstruct the Distension of the Bladder.

Having try'd the Former Experiment with a lighted Match, in a small Receiver, I found, that the Fire was quite extinguish'd with it's own Smoak, before the Cover could be cemented on, except the overplus of Smoak was successively pump'd out, and a Supply of Fresh Air was let in at the Stop-Cock; which Method would con∣tribute to the Preserving of it.

EXPERIMENT XIV. Of the Striking of Fire, and Explosion of Gun∣powder in Vacuo Boyliano.

* 1.74HAving fasten'd a Pistol to a Prop, which was plac'd in a Perpendicular Situation in the Receiver, and having ty'd a String to the Tricker, the other End of which was fix'd to the Key above-mention'd, in the middle of the Cover, we turn'd the Key round, to shorten the String; by which means the Tricker being check'd, and the Flint as it is usual, falling upon the Steel, it struck Fire, tho' the Receiver was exhausted, as a Pistol usually does; tho' by the

strongest Collision we could contrive, we could not, in our Engin, strike Fire with two pieces of Steel, striking one upon another.

But we observ'd, That having endeavour'd several times, without Success, to fire Gun∣powder, we, but once or twice, met with the desir'd Effect: Where we observ'd, That the Flash was more expanded, than if it had been exploded in the open Air; and that when the Flash was extinguish'd, the Receiver was full of Smoak, the Parts of which mov'd up and down very briskly, but much swifter, when Air was permitted to return into the Cavity of the Re∣ceiver.

EXPERIMENT XV. The Ʋnusefulness of Kindling Bodies inclos'd in Va∣cuo Boyliano, with a Burning-Glass.

HAving conveig'd some Black and Dark Combustible Matter, into a small Receiver, and plac'd it in the Sun-shine; a Good Burning-Glass threw the Rays of the Sun so powerfully up∣on it, as to make it smoak, and fill the Receiver; but the Air getting into the Cavity of it, we could not prosecute the Experiment. And having repeated the Tryal in our Large Receiver, we found the Glass so thick, that it broke the Rays of Light, and scatter'd them so much, that when they fell upon the Combustible Matter, they were altogether incapable of working any considerable Effect upon it.

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EXPERIMENT XVI.

* 1.75HAving plac'd a piece of Wood in our Re∣ceiver, with a piece of Iron, in a Perpen∣dicular Line, upon it; and fix'd a well-pois'd Needle upon that, we pump'd out the Air, and then apply'd a Needle to the outside of the Re∣ceiver; and observ'd, That the Load-stone drew or repell'd the Needle, as a Load-stone usually in the open Air; and the Needle, upon a Re∣moval of the Load-stone, after some tremulous Vibrations, pointed North and South again.

EXPERIMENT XVII. The Gravity and Rarefaction of the Air examin'd, by the Torrecellian Experiments; together with Considerations concerning a Vacuum, &c.

* 1.76COnsidering that it would be a very probable Method, to inform us, how far the Pressure of the Atmosphere, contributes to the buoying up of Mercury, in a Cylinder, so many Digits above the Surface of the Mercury it leans on, to try, whether in our Engine, as the Air was more or less exhausted, the Mercury in the Tub would accordingly subside; we fill'd a Glass-Cylinder Hermetically seal'd with Mercury, whose Bore was about a quarter of an Inch Diameter, and 3 Foot long; which being inverted in an oblong Box, and carefully let down into the Receiver; and the Cover lutedon, the Tube came through the Hole in the midst of the Cover, the Cranies be∣ing fill'd with melted Diachylon; where it was

observ'd, That the Mercury remain'd elevated to the same height, as if the Foot of the Tube had been press'd upon, by the Atmosphere, the Air included in the Receiver being in a compres∣sed State, and acting by Virtue of it's Spring.

The Cylinder of Mercury being thus plac'd in the Receiver, we caus'd a Cylinder of Air to be pump'd out, and after that, another, observing the Mercury after each, gradually to subside; till at the last, it subsided a considerable way in the Pipe, down into the Body of the Receiver: and to put it beyond dispute, that the Subsiding of the Mercury, depended upon the weaken'd Spring of the included Air, and the Aequili∣brium betwixt the Pressure of that, and the Gra∣vity of the Mercury; we turn'd the Key, and permitted Air gradually to re-enter; and ob∣serv'd, That the Mercury accordingly rose in the Pipe, almost to the height which it was first su∣spended at; and the Reason why it was not rais'd quite so high, was, because several Bubbles of Air, which were before mix'd with the Mer∣cury, rising above it, depress'd, and kept it from ascending, by taking up more room in the Top of the Cylinder.

In trying of which Experiment, having once made use of Diachylon Plaster, to stop up the Top of the Tube, we found, that tho' the Mer∣cury subsided considerably upon the Operation of the Pump; yet the Air so powerfully insi∣nuated it self through the Diachylon Plaster, that it sunk in the Pipe insensibly of it self.

Another thing observable in this Experiment, was, that if, when the Air was exhausted, it were again permitted to run in too fast, it would

go near to break the Cylinder, by forcing the Mercury up too quick.

Besides we observ'd, as we have before inti∣mated, That tho' upon the First Exsuctions, the Mercury subsided above an Inch; yet when it was low in the Receiver, it would not subside over the Breadth of a Barley-corn; besides, by reason of the Parts of the Air, tending to a Restitution of their Springs, it check'd and caus'd the Quick∣silver after it's descent, to fly back again a little after each Exsuction.

Another thing remarkable in this Experiment, is, That having try'd it in one of our small Re∣ceivers, we found, that at one Exsuction it fell 18 Inches and a half, and at another time 19 and a half; from whence we may infer, that it might be of no small use to consider, the various Phae∣nomena afforded by the different Magnitude of the Receivers, in which these Experiments are made; and also the various Bores of the Cylin∣ders, which contain the Mercury; for thence one might probably guess at the Quantity of Air ex∣tracted out of the Receiver, by the Subsiding of the Mercury in the Tube.

To the foregoing Observations, we shall add, That having once try'd the Experiment, in a Tube about two foot long, I found, that upon the first Exsuction, the Mercury fell above a Span, and afterwards subsided by degrees, till the Air was re-admitted, and then it was rais'd near to the top of the Tube again.

Lastly, It hath been observ'd, That when, by the help of the Pump, more Air hath been squeez'd into the Receiver, than what was forc'd in by the Weight of the Atmosphere, the Mercury

would rise above 27 Digits in the Tube, and would be suspended at that height, till the Air was again let out.

* 1.77Having said thus much of the Torrecellian Ex∣periment, and the several Phaenomena observable in it, perhaps it may be expected, that I should say something, concerning that Controversy, Whether or no there be a Vacuum in the Re∣ceiver, when the Air is pump'd out: But being unwilling to take it upon me to determine so nice a Controversy; I shall only intimate, that were the Cavity of the Receiver void of Matter, it would be a difficult thing to conceive, how we should have visible Idea's of things contain'd in it; since they must either be convey'd to our Sen∣sory by the reflected Rays of Light, or they must proceed from some sensible Emanations from the Bodies themselves. And from the foregoing Six∣teenth Experiment, it appears, That the Effluvia of a Load-stone do permeate the Cavity of the Receiver, which makes it probable, that the Magnetical Steams of the Earth do so too.

But on the other hand, it may be alledg'd, That since the Effluvia of a Load-stone may be ad∣mitted into the Receiver, when it seems full of Air, it may be urg'd, that the subtle Emanations of that Substance are only dispers'd through the Vacuities of the Air; and consequently when that Air is exhausted, the Spaces which the Air posses∣sed before, may be left void of Matter; for from the Thirteenth Experiment it appears, that Mat∣ter, which, if closely pinned up together, takes up but a small Space, may be dispers'd through∣out the Receiver, a very small Portion of the Match being able to fill the whole Cavity of it

with Fumes. And as for the Arguments before alledg'd in favour of a Plenitude; they rather seem to argue, that it may be, than that it really is; and the Consequences usually drawn in Proof of such a Plenitude, are rather grounded on the Cartesian Notions of a Body, than on Substantial Experiments; for they thinking it a Contradi∣ction in Adjecto so say, a Space can be void of Body, since they make Body and Extension inse∣parable; they therefore in favour of their own Doctrin draw Inferences from their own Positions to argue for a Plenitude.

But to leave so Nice and Doubtful a Dispute, I shall proceed to lay down the following Adver∣tisements: First, That the Difference which sometimes happens betwixt the rising of Mercury here in England, and beyond Seas, being about two Digits, it rather proceeds from the Short∣nese of our English Inches, compar'd with those beyond Seas, than any such considerable Diffe∣rence in the Weight of the Atmosphere. Ano∣ther thing to be advertised is, That except more than ordinary Care be taken, when the End of the Cylinder is immers'd in the Vessel of Mercury, several Bubbles of Air will rise to the Top of the Tube, which, being condensed with Cold, will permit the Mercury to rise higher in the Tube; but being expanded with Heat, would sensibly depress it. And,

If it should be demanded, What Methods are to be taken to prevent the Intrusion of the Air, the following Requisites are to be observ'd: First, the lower Orifice of the Cylinder must be smooth, and so much inverted on each side, as not to exceed a quarter of an Inch in Diameter.

Secondly, the Tube must be fill'd so full, as not to admit of any Air, betwixt the Finger and the Mercury. Thirdly, before the Tube is quite fill'd, it will be requisite to invert the Tube, that the Air included in it, may, by ascending to the Top, and upon a Re-inversion back again, gather all those little Bubbles of Air, which are dispers'd through the Mercury, as it passes from one end of the Cylinder to another; and to drain the Mercury more exactly you may, by applying a hot Iron, cause those less Bubbles, which are not excluded by the former Method to break forth, which will be promoted by shaking the Vessel upon every Drop of Mercury, put into the Pipe. By which Method, having in a great Measure clear'd the Tube of Air, I have, in one, that was pretty short, rais'd the Mercury to no less than 30 Digits and an eighth.

EXPERIEMINT XVIII. The Variation of the Rise of the Mercury in the Glass-Cylinder, and the Reason of it consider'd.

HAving fill'd a Tube about 3 foot long, with Mercury, and plac'd it in a wooden Frame in the Window, I observ'd, the Mercury was sensibly depress'd in hot Weather, by the Ex∣pansion of the Air, which swam about it, and rais'd again in Cold; the Altitude very often varying without any manifest Cause: So that in five Weeks time it had ascended and descended about two Inches; the utmost descent below the Altitude of it's first Suspension, being 9/16 of an Inch; and it's utmost Descent being 7/16, and it is

not improbable, but that the Variation of the Altitude of the Mercury, would have been more considerable, had the Experiment been try'd in a longer Tube, and in the open Air.

And here it may be seasonable to take notice, that could there be any sensible Variation, ob∣serv'd in the Altitude of the Mereury upon the Ebbing and Flowing of the Sea; it would be of no small Moment in determining whether the Pressure made upon the Air, by the Moon, were any ways concern'd in causing the Ebbing and Flowing of it, and such like Phaenomena.

But to return to what we observ'd further: Having taken the Cylindrical Tube out of the wooden Frame, on a snowy day we observ'd, that the Mercury was rais'd Twenty nine Digits and three Quarters, above the Basis which it lean'd on.

If it should be ask'd, from whence these Va∣riations in the Altitude of the Mercury. pro∣ceeded? I shall offer the following Considera∣tions.

• ...* 1.78 First. That the Air above the Mercury, being very weak, and not able to make any strong Resistance to the Rising Mercury, it may be esteem'd a Cause, why it rises no higher, be∣cause the Asmosphere is able to sustain no more of it; forasmuch as the Mercury and the At∣mosphere are ballanc'd in an Aequilibrium; for the Resistance which the Air above the Mer∣cury can make, is so small, that it would rise but very little higher, were there none at all in the Top of the Tube.

• Secondly, We may consider, that the External Air is subject to many more Alterations and Changes, than the Internal contain'd in the Top of the Tube, the latter being subject to be wrought on only by Heat and Cold: But the former is subject to many and considerable Alterations, besides those observable in this Experiment, the Effect of its fainter Changes being evident by their Effects on bruis'd and feeble Bodies. And that there are considerable Changes in the Air,* 1.79 is further evident from what Kircherus, during his Stay in Malta observes concerning Mount Aetna, which he could see from that place on some days, tho' on others, which seem'd clear, the Air was so condensed, that he could not dis∣cern it; and thet the like Changes of the Air have sensibly alter'd the Prospects of several Pla∣ces, is too commonly known to need further Instances: And we our selves have often taken Notice of plentiful Steams and Exhalations in the Air, by the use of Telescopes, which could not otherwise be taken notice of, which after a Showr of Rain would presently disappear: And that such Steams do rise from the Earth, hath been observ'd by Miners, who are often too sen∣sible of Damps, which except timely prevented, make the Air so thick and muddy, as to put out their very Candles. And that the Thickness of the Air may contribute to the raising of the Mercury in the Pipe, appears from what hath been before observ'd in the Torrecellian Experi∣ment.

And since the External Air is liable to be al∣ter'd so many ways, by the Mixture of insensi∣ble Corpuscles of Matter, its Rarity and Densi∣ty

are sufficient to account for the several Varia∣tions in the Height of the suspended Mercury; since accordingly as the Air is Rarifi'd, its Pres∣sure in Bodying up the Mercury must accordingly be varied.

EXPERIMENT XIX.

* 1.80TO try whether a Cylinder of Water would subside in our Receiver as the Cylinder of Mercury did, we fill'd a Cylinder of four foot long with it, which being inverted, and the low∣er end placed in a Glass Vessel, we let it down in the Receiver and closed it up; which being done, and the Pump set on work, we found that it did not in the least subside till such a Quantity of Air was exhausted, as to leave the included Air so much weaken'd in its Spring as to be work'd upon, and over-power'd by the weight of the Water; and then, upon every Suction, it sensibly subsided, tho' not so much as the Quicksilver; for whereas the Quicksilver sub∣sided till it fell within an Inch of the Basis, the expanded Air remaining in the Receiver, was able to bear up the Water a Foot high. But the Experiment being try'd in a small Receiver, the Quantity of Air included in that, coming near∣er to an Aequilibrium with the Cylinder of Wa∣ter, it sensibly subsided upon the first Exsuction; and much lower upon the second, and sometimes not much less than two foot; and the Water in this as well as the former, upon a reingress of Air rose to the Top of the Cylinder, but with more Speed than the former.

EXPERIMENT XX.

* 1.81TO evince that Water hath, besides a no∣table one, a languid Elater, we fill'd a Glass Bubble with a long Neck, term'd by the Chymists a Phylosophical Egg, about a Span a∣bove the Bubble, with Water; where fixing a piece of Paper, we conveigh'd it into the Re∣ceiver, and found, that, after part of the Air was pump'd out, the Water sensibly rose upon every Exsuction, the breadth of a Barly-Corn; and upon the ingress of the Air presently subsi∣ded to its former place. Another Instance of the Air's Expansion, I obtain'd by filling a round Pewter Vessel with Water at a small Hole, which being stop'd with Soder, and the Vessel bruis'd in several places, to compress the Wa∣ter, the Vessel being perforated with a Needle, it spun out with Force enough to raise it a con∣siderable height into the Air.

EXPERIMENT XXI.

* 1.82HAving fill'd a Glass Viol with Water, which contained something above a Pound, I took a Glass Pipe, about as thick as a Goose Quill; and having put one End of it into the Neck of the Bottle, and clos'd it with Cement, I fill'd the Pipe half full with Water, sticking a piece of Paper at the Superficies of the Water on the outside of the Pipe, which being plac'd in the Pump, after the Air had been pump'd a while; above sixty Bubbles of Water as big as Pease rose out of the Water, one after another;

and the Water in the Bottle so far expanded, as to rise quite up to the Top of the Pipe; and be∣ing permitted to subside, several Bubbles of Air rose out of it afresh, as soon as it renew'd its Ex∣pansion as before; but upon a reingress of the Air, it presently subsided almost to the Bottom of the Pipe.

Besides which, the following Phaenomena were observable: First, That those Bubbles, which as∣cended last, were much larger than the former, either, because their Parts were more expanded than before, or because more Bubbles of Air were united together, but whatever was the Cause of it, we observ'd, that they ascended much slower than before.

Another thing to be observ'd was, that tho' Bubbles are usually wont to rise above the Sur∣face of the Water, encompass'd with a thin Film; yet, in this Tube, the Surface of the Water being Convex, the less protuberant Parts of the Bubble were covered with Water.

Another Observation which occurr'd was, that whereas those Bubbles which rose at the Beginning of the Operation, divided the Water which they pass'd through, in their Ascent; these latter expanded Bubbles, filling up the Cavity of the Cylinder in their Passage, rais'd the Wa∣ter before them; till the Air was again permit∣ted to re-enter the Receiver, and then they wholly disappeared.

From which Observations it may Naturally be inferr'd; First, Bodies under Water may be press'd upon by the Atmosphere, as well as in∣cumbent Water; Secondly, It cannot be hence inferr'd, that the Intumescence of the Water

proceeded from any Elasticity in it; since, it might more probably proceed from the Elasticity of the Air lodg'd in the Pores of the Water. And to make it probable, that those Bubbles proceeded from small Particles of Air, dispers'd through the Pores of the Water, and not from any spirituous Parts of the Liquor expanded, I shall subjoyn the following Experiment.

EXPERIMENT XXII. The Bubbles prov'd to be Aerious, and not Watery, by observing the like Bubbles in î Mercury: To which is subjoyn'd a Digression, whether the Air is ge∣nerated de Novo, &c.

THO' it be generally alledg'd, that the Bubbles which rise in the Cylindrical Tube, in the foregoing Nineteenth Experiment, are Particles of Water expanded, upon a Dimi∣nution of the Incumbent Weight of the Air; Yet I am apter to believe them really Parts of Air dispers'd through the Water; because, up∣on the re-entring of the Air, the Water was not impell'd quite to the Top, but was depress'd, by the Air lodg'd above it, almost an Inch, which, being collected together, was able to resist the Pressure of the Air.

* 1.83But in order to a further Discovery, whether the aforesaid Bubbles were Water or not? We try'd the Nineteenth Experiment in a small Re∣ceiver, and upon drawing out the Air, the Water subsided; upon which, several Bubbles rising to the Top of the Cylinder, prevented the Rising of the Water, half an Inch, being

possess'd by the Bubbles of the Air, collected at the Top of the Cylinder: And we were further perswaded, that those Bubbles were Aerial, be∣cause the Air, being a second time exhausted, the Water contain'd in the Tube, was, by the Spring of that Air contain'd in the Cylinder, depress'd below the Surface of the Water which was without the Tube, having a Convex Super∣ficies, as Water expos'd to Air in such Tubes usually hath, but rather more protuberant: And to demonstrate, that those Bubbles were really made up of Aerial Particles, when the Air was almost exhausted, and the Water had subsided near as low as the external Water, by applying Water to the Tube, which contain'd the Air, we observ'd that it was so far expanded, as to depress the Water down to the Bottom of the Tube, several Inches below the External Water: So that the Air, which was before ex∣panded to near a hundred times it's extent, was capable of being further expanded by Heat.

But I was yet further confirm'd in my Opini∣on, that those Bubbles were nothing but Air, lodg'd in the Pores of the Water, because the Air being exhausted out of the Receiver, the subsiding Water yielded not Bubbles as before, except a few small ones, when it was near pump'd out. And what I took for a stronger Argument was, that the same Experiment being try'd with Mercury, several Bubbles likewise rose to the Top of the Cylinder; and the Mercury subsiding a second time, upon the Exsuction of the Air, several Bubbles appear'd in the Bottom of the Cylinder; which grew bigger and bigger as the Surface of the Mercury descended lower. From

whence it appear'd, that a Body,* 1.84 more ponderous than Water, might contain Aerial Particles in it's Pores, capable of expanding themselves, when the Cause of their Compression is taken away; so that we have Reason to believe, that the Intumescence of the Water, not only in these Experiments, but also the 〈 in non-Latin alphabet 〉〈 in non-Latin alphabet 〉 of the Water, contain'd in the Pewter Globe before mention'd, proceeded from the Expansion of the Aerial Par∣ticles contain'd in the Pores of the Water, ra∣ther than from any Elasticity in the Water it self.

These things being premis'd, it would be a Mat∣ter of some Importance, and of no small Conse∣quence,* 1.85 to determine, whether what we have said of the Air be true, to consider whether Air be really a Primogenial Body, and inconvertible in∣to Water, and Vice versâ, or not: But it being as difficult, as requisite, we shall rather chuse to offer what may be urg'd of either the Affirmative or the Negative.

And first, in favour of the inaptitude of Air to be turn'd into Water, or of Water into Air, it may be urg'd; that besides, that it hath been the Opinion of several Philosophers, it hath likewise been found impossible by Experience to effect such a Change in either of them; And the diligent Schottus Mecham. Hydraulicopneumat. Part 3. Class. 1. relates, that in the Musaeum Kircheria∣num, Water hath been hermetically seal'd in a Glass with a long Neck, and kept there this for∣ty Years, without undergoing any Change: Nor, indeed, do we perceive the least alteration in the Nature of Air, Hermetically seal'd in Glasses for Chymical Uses, tho' it may acquire several Degrees of Heat in them: And it may very

plainly be seen, that tho' Water is divided into smaller Parts, and rais'd in the form of Vapours, by Heat; yet it is so far from being turn'd into Air, that in Chymical Distillations, it falls down into the Receiver in the form of a Liquor. And likewise Volatile Spirits and Salts, tho' their Parts swim up and down in the Receiver for some time, yet the former presently con∣dense into a Liquor, and the latter, into Salts.

And further it may again be urg'd, that tho' the Parts of Water may be put in such an Agi∣tation, as in some measure to counterfeit the form of Air, yet since the quick Coalition of those Parts into a fluid Form, argues the impossi∣bility of giving them a due Texture, requisite to add to Air the Springiness observable in it; it is a strong Argument against the Possibility of effecting such a Change. And that a bare Mo∣tion and Agitation of Parts is not sufficient to add Springiness to a Body, appears from the foregoing Experiment concerning a piece of Match, included in our Receiver; where the Agitated Parts of Smoak, were by no means capable of hindering the Expansion of the Blad∣der contain'd in it.

And tho' Josephus Acosta tells us, that Grates of Iron have been so much corroded in the Air, as to be turn'd into a Substance which would crumble into Powder like parched Straw; and tho' the Accurate Varenius hath observ'd in the Issands call'd Azores, that by the Sharpness of the Air even the Tiles of the Houses have been corroded; yet are they no Arguments, that such corrosive Humors may put on the form of Air;

since such Phaenomena may be accounted for, by the Mixture of corrosive Steams mix'd with it; which are so far from being endow'd with the true Qualities of Air, that they may, notwith∣standing they are mix'd with the Air, retain their own Natures; which is evident in subliming of Sal Armoniack. And I have had a subtle Saline Body, which would not only rise it self, retain∣ing it's own Nature, but would also raise the Sub∣stance of Gold along with it, whose Parts would also retain their own Natures, and stick to the Top of the Receiver like pure Gold.

I remember that once having ty'd a Bladder to the Neck of an Aeolipile, when the Water was forc'd out into it, so as to distend it, we slip'd it off, and having ty'd it close, put it into our Receiver; where we observ'd, that upon the Exsuction of the Air, it was considerably expan∣ded: And tho' the Bladder, when taken out of the Receiver, continu'd in the Cold for some time; yet the included Substance continu'd near as fully distended: But notwithstanding the Plau∣sibleness of this Experiment, I could not but su∣spect, that the Distension rather proceeded from the Air, which upon the first working of the Aeolipile came out with it, than from any parts of the Water converted into Air.

But to proceed to what may be alledg'd, to Countenance the Change of Water into Air; If a good Aeolipile be plac'd upon hot Coals, the Water will sometimes spring three or four foot high into the Air; and when taken off the fire, will continue to emit copious Streams: And if, when it is taken from the fire, almost empty, the Neck be immers'd in Water, as soon

as it begins to suck in Water, it will raise Store of Bubbles, which seem to proceed from Water too much expanded by the Heat of the Aeolipile; and if, when that Aeolipile is almost full of Wa∣ter, a live Coal be held before the Neck, it will manifestly be kindled, by very vehement Steams which flow out of it, which will have the more powerful Effects, the nearer the Coal is held to the Mouth of the Aeolipile.

But since by holding a Knife before these Steams, they will be condensed upon it into Water; and thence appear not so much to have acquir'd the Nature of Air as to have their Parts put into a violent Motion, I shall add a Relation from the Industrious Kircher, of a Famous Hudraulick Engine,* 1.86 which he made by the Order of Innocent the Tenth. The Ac∣count of it, in his own Words, is the follow∣ing, Cum eodem tempore quo haec scripsi, Summi Pont. Innocentii X. Mandato Organi Hydraulici in Horto Quirinali constituendi Cura mihi com∣mendata esset, Aeoliam Cameram insigni sane Successu construi jussimus, ea quae sequitur Ra∣tione.

Erat Longitudo seu Altitudo Camerae (A H) quin{que} Pedum, Latitudine tres fere ex Lateribus, con∣structa, in Medio duo continebat Diaphragmata (C D) & (E F) in Modum Cribri pluribus Fora∣minibus pertusi. Paulò infrà Canalis (G) Aquam advehens inserebatur in (H) eidem Epistomium parabat Exitum. Aqua ita{que} per Canalem (G) maximo Impetu ruens vehementissimum Ventum mox intus excitabat; qui Ventus nimiâ Humiditate imbutus, ut purior ••xiret siccior{que} Diaphragmata illa in Cribri Modum pertusa, ordinata sunt. Intra

haec enim Aquae vehemens Agitatio, rupta fracta{que} Aerem puriorem per Canalem (A) subtiliorem e∣mittebat: Verum cum postea inventum sit Aerem plus aequo humidum interioribus Organi Meatibus maximum Detrimentum inferre: Hinc, ut Aer aquosus siccissimam Consistentiam acquireret, ordi∣navimus Canalem plumbeum (Q R) in Haelicem contortum Vasi (S) aliquantulum capaciori in modum Ʋrnae efformato, insertum. Intra Ʋrnam enim plumbeam & Canalem tortuosum illisus Aer humidus, ita ab omni Aquositate defaecabatur ut ex Furno in Organum derivatus dici potuerit. Ʋrna (S) Canalis tortuosi (Q R) ultimum Orificium (Z) inseritur Anemothaecae Organi. Et hunc Mo∣dum Organis Hydraulicis omnium aptissimum re∣peri.

And I rather cite this Account, because it is deliver'd as Kircher's own Observation; and had I, when I was at Rome, taken notice of these Engines; and found that the Effluviae which blew the Organs, were not again con∣densed into Water, I should be apt to believe it not impossible to turn Water into Air; it being altogether impossible, That the Air lodg'd in the Pores of the Water, should sup∣ply so large a Quantity of Air, as is requisite to blow the Organs: I therefore was induc'd to think, that it might proceed from some Parts of the Water put into a very brisk Moti∣on, since I had observ'd, as I pass'd betwixt Lyons and Geneva, that the River of Rhone, be∣ing on a sudden straitned betwixt two Rocks, which are so near, that a Man may stand with one Foot upon one, and the other Foot upon the other, some Parts of the Water were put into

so violent a Motion, as to be rais'd into the Air a considerable Height, and at a distance to ap∣pear like a Mist; tho' I must confess it difficult to conceive, how such Vapours should pass through a leaden Pipe of such a Length, since we see that Vapours are condensed into Liquids, in a much less time, in the Heads of Alembicks, and the Necks of Aeolipiles, when once the Motion of their Parts are checked by Cold.

But leaving this plausible, tho' not satisfacto∣ry Experiment, I shall proceed to another, which is this; Having filled a Glass Bubble, ca∣pable of containing about three Ounces, with near equal Parts of Oyl of Vitriol and Water, half a dozen Iron Nails being cast into it, we stopp'd the Cylindrical Neck of the Tube with Diapalma, so close, as to exclude the Air alto∣gether; which being done, we immers'd the Neck of this Bubble into a Glass Vessel full of the same Liquor, and in a little time perceiv'd Bubbles to rise to the Top of it, being rais'd by the Heat produced by the Action of the Oyl upon the Nails; and this Air was so much in∣creas'd, in a little time, as to depress the Water quite out of the Bubble into the Cylindrical Neck of it: But lest that Pressure should be thought to proceed from the Agitation of those insen∣sible Parts of Matter, we observ'd, That tho' the Vessels were expos'd to the Air for four days, to give the Motion of the Parts time to cease, had the Effect proceeded from them; we observ'd, That the Liquor, all that time, continued depressed, the Space beforementio∣ned being filled with Air. And, what was worthy to be noted, Upon a small degree of

Heat approaching the Bubble, the included Air was further dilated. And the like Phaenomena succeeded upon a Tryal with Nails corroded in Aqua fortis; From which Experiments, it might be inferred, That if Water be not con∣vertible into Air; yet it seems probable that it may be generated anew.

And that Air and Water are mutually con∣vertible into each other might further be urg'd, as nothing but what the Aristotelians teach and allow of. But we shall rather urge, That if what Democritus, Lucippus and Epicurus, toge∣ther with other Naturalists teach be allow'd of, viz. That the Qualities of Bodies depend on the different Figures, Shapes and Textures of the Parts of Matter, they consist of; it will be reasonable enough to think, That the Texture of the Parts of Water being alter'd, they may acquire the several Qualities of Air; since it is certain, That the Parts of Matter may, by a lucky Concourse of Causes, become springy: So Silver by being beaten with a Hammer ac∣quires Springiness, which it loses by being heated in the Fire, and becomes flexible.

EXPERIMENT XXIII.

* 1.87IN Prosecution of what was deliver'd in the foregoing Experiments, We filled a Glass call'd a Philosophical Egg with common Water, about a Foot and a half high; it being large enough to contain about nine Ounces, and the Diameter of the Neck being, at the Top, half an Inch, and at the Bottom an Inch; this being put into the Receiver, and the Pump ply'd,

when the Air was pretty well exhausted, several Bubbles rose to the Top and broke; but all of them finding an easy Passage through the Water, did not elevate it as when they ascend∣ed in a narrower Cylinder; but upon an Admis∣sion of Air into the Receiver again, the Water was sensibly depressed.

To try whether distilled Water was more subject to expand than common Water; I put two Ounces of it into a Glass Bubble, which wrought to the Middle of it's Neck; but it neither swelled nor yielded Bubbles upon an Exsuction of the Air.

But having put distilled Water into two di∣stinct Philosophical Eggs, the Neck of the for∣mer being straitned with a Glass Tube, we plac'd them in the Receiver, and found a mani∣fest Difference upon the Exsuction of the Air; for in that which was straitned, the Air ma∣nifestly elevating the Water, several Bubbles were gather'd about the bottom of the Glass Tube; whereas in the other Egg, the Water was not in the least elevated; and though the Bubble in the last-mentioned, disappear'd upon the Re-ingress of the Air, those above the Tube continu'd visible, only a little contracted, for a considerable time; the Surface of the Water, which was before elevated, being de∣pressed lower than when first put into the Egg.

And after a days time having again ply'd the Pump, we observ'd, That the Bubbles were so much drawn out before, that we could scarce discern a Bubble in either; but that in which the Cylindrical Tube was plac'd, swell'd the

Breadth of a Barly Corn, tho' the other did not; yet, in the former, upon a Re-ingress of Air, it subsided again, and whether that Swelling was caus'd by the Rarefaction of the Water, or the Spring of some latent airy Parts, is not easy to determine.

EXPERIMENT XXIV.

* 1.88HAVING put Sallad Oyl into a Glass about the Size of a Turkey's Egg, whose Stem was near ⅓ of an Inch in Diameter, the Liquor reaching up to the Middle of the Stem, we plac'd it in the Receiver, together with the like Vessel fill'd to the same Height with Wa∣ter; and upon drawing out the Air, the Bub∣bles were not only more copious than those of the Water, but rose much sooner as well as longer, continuing till the Pumper was quite tired with Pumping; and what was very re∣markable in this Experiment was, that when the Oyl was put into the Receiver, before the Receiver could be closed, and the Pump put into Action, it subsided near half an Inch in the Stem.

Having put Oyl of Turpentine into a Glass Bubble, we observ'd, That it afforded a good Quantity of Bubbles, which expanded them∣selves in their Ascent, and would sometimes raise the Oyl in the Tube so much as to make it run over.

But besides the foregoing, we try'd the like Experiments with other Liquors, amongst which, a strong Solution of Salt of Tartar afforded very few Bubbles, and those much

later than other Liquors: Spirit of Vinegar likewise yielded very few. Red Wine afforded Bubbles pretty plentifully, which chang'd Pla∣ces by moving in an oblique Ascent, and for∣med a sort of Froth near the Top, which pre∣sently disappear'd: Milk afforded plentiful Bubbles, which elevated that Liquor more than common Water.

We likewise put Eggs into the Receiver, to see whether the Substance contain'd in the Shells would break them; leaving the Film within it whole, as that Substance frozen had done; but it succeeded not.

We put Spirit of Urine into a Glass Egg, filling another up to the Middle of the Neck with common Water; to which we added as much Spirit of Wine as rais'd it half an Inch higher; and into a Glass which differ'd from the former only in having a flat Bottom, we pour'd rectify'd Spirit of Wine, till it rose to ⅔ of the Neck: And the Edges of these three being mark'd, we put them into a Receiver. Upon the Exsuction of the Air the Mixture of Water and Spirit of Wine afforded very few Bubbles: The Spirit of Urin swell'd near an Inch and a half above the Mark, affording Store of Bubbles, which formed a Froth, upon which several larger Bubbles lay, which were plac'd one above another, to the Top of the Tube: The Spirit of Wine afforded Bubbles till we were weary of pumping, which ascended very swiftly, and immediately disappear'd at the Top, first lifting up the Surface of that spiritu∣ous Liquor so as to form a thin Film. And it was further observable, That the Motion of

these Bubbles in their Ascent, was in a strait Line; whereas those of the Water and Wine made a Line, which on each side appear'd like the Teeth of a Saw: And lastly, in this Spirit we took Notice, That the order which these Bubbles ascended in, was in Lines parallel, and of an Equal Distance from each other; the Bub∣bles likewise following each other, in such an order, as to form a sort of Bracelet, one end of which seem'd to rise from a certain Point at the Bottom of the Glass.

When Air return'd into the Receiver, the Bubbles on the Spirit of Wine gradually sub∣sided; yet neither that, nor the Mixture of Water and Spirit were depress'd below the Mark: But the Spirit of Wine continu'd ex∣panded, near half an Inch, which I found to suc∣ceed upon several Tryals.

EXPERIMENT XXV.

* 1.89HAving fill'd a Wide-mouth'd Jar, with about half a Pint of Common Water; we sunk two Glass-Viols, whose Shape and Size is represented by the Eighth Figure, one of which contain'd just so much of a Ponderous Mercurial Mixture, as was requisite to sink it, when co∣ver'd with white Wax; the other being weigh'd down by Water, and the Mouths being down∣wards; the Quantity of Water contain'd in the former, filling three Parts of four of the Glass, the Air contain'd in the latter being equal in Dimensions to a Pea.

These being let down into the Receiver, upon plying the Pump, at the last so many Bubbles

rose up to that which swam upon the Water, as were able, by expanding themselves, to cause some of the Water to fly out, and make the Viol emerge to the Top of the Water contain'd in the Jar; where at every Exsuction it conti∣nu'd to expand, till it was able to raise up the side of the Viol, and in part to evacuate it self; upon which it presently swam upon the Water, as before, and eight times after discharg'd a Bubble of Air about the Size of a Pea; but, when we permitted the Air to enter in again, it presently subsided to the Bottom. As for the other, it continu'd at the Bottom all the while. But some time after, the Pump being ply'd, it rais'd it self considerably; but about sixty Parcels of Air as big as Peas, finding vent, and getting out, it presently subsided; tho' upon a further Expansion of the Air, it rose again, and subsided, which successive Ascent and descent, it continu'd Nine times after after the Pump ceas'd working; but when the Air was again let in, it was presently fix'd at the Bottom. From which Experiment, that Hydrostatical Rule, That a Body will swim in the Water, if it be lighter than its equal Proportion in Bulk, will appear to be likewise true, when the Weight of the Atmosphere is taken off.

EXPERIMENT XXVI.

* 1.90IT being usually taught, That the Motion of a Pendulum is something quicker, accordingly as the Medium it moves in, is thinner; we su∣spended one, which weigh'd about twenty Drachms in our Receiver, fixing it to the Cover

by a piece of Silk; and having fix'd another of an equal weight without the Receiver, we gave them both an equal Motion, and observ'd, that whilst the Latter made twenty Vibrations, the Former counted twenty; but the Pendulum, be∣ing afterwards put into Motion in the exhausted Receiver, and likewise in the same Receiver, before it was exhausted, continu'd it's Vibrations to an equal space of Time in both; so that from what we could observe, the Difference of the Vibrations in Air, and that more rarify'd Me∣dium, viz. the exhausted Receiver, was scarce sensible.

EXPERIMENT XXVII.

* 1.91IT hath been the receiv'd Opinion of the Schools, That the Air is the Medium, through which Sounds are conveigh'd: But the Indu∣strious Kircher having observ'd, that if a Bell be fix'd in the upper end of a Tube, and, upon making the Experiment de Vacuo, be left there, a Load-stone apply'd to the side of the Tube, will attract the Steel-clapper; which, upon a Re∣moval of that Load-stone, will fall upon the other side of the Bell, and cause an Audible Sound: He thence infers, That the Medium through which Sounds are conveigh'd, must be much more subtle than the Air. But to evince the contrary, we suspended a Watch in our Receiver, by a Packthred, and observ'd, That the Sound was not only audible at the sides of the Receiver; but that that which was likewise perceiv'd by the Ear, held near the Cover, was different from that which we heard at the sides of the Receiver; but the

Air being drawn out, we could not perceive the least Sound, tho' the Motion of the Minutes assur'd us, that the Pendulum continu'd it's Mo∣tion; yet upon admitting of Air again into the Receiver, the Sound was again renew'd; which Experiment seems to evince, that the Air is the Chief Medium, through which Sounds are con∣veigh'd: Yet it is not a little strange, that so slight a Stroke as that of the Pendulum, should give such an Impulse to the Ambient Air, as to inable it to communicate a Motion to the sides of the Receiver, strong enough to put the External Air into an Undulating Motion.

But having supported a Bell in the Middle of our Receiver, by a large Stick, which reach'd from one side to the other, the Diameter of the Bell, being about two Inches, we observ'd, that tho' the Sound in the Receiver, was not equally as sharp as in the open Air; yet there was no considerable Variation, when the Air was drawn out; which evinces, that a subtler Medium than the Air, is not altogether incapable of propa∣gating Sounds, no more than Air; however, in the foregoing Experiment try'd with a Bell, su∣spended in a Glass-Tube, it may not without Reason be suspected, that the Cavity of the Tube was not wholly void of Air, since Expe∣rience informs us, that it is impossible to fill the Glass-Cylinder, so as to keep the Upper Part of the Tube void of Air, since the Aery Parts lodg'd in the Pores of the Mercury, fly up into it.

And further on this Occasion, to shew how far the Air is the Principal Medium of Sounds, we might alledge, that it was observable in a

former Experiment, that tho' upon the strik∣ing of Fire, with the Lock of a Pistol in our Receiver, the Sound is audible; yet it is much more dead, than when made in the open Air: And the like Variation is observable in all other Sounds made in our Receiver.

EXPERIMENT XXVIII.

* 1.92FOR a further Confirmation of what hath been deliver'd in the XX^th Experiment, viz. That the Air included in our Receiver, makes as strong a Pressure upon Bodies encompass'd by it, as if they were expos'd to the Pressure of the Atmosphere; we put a Viol, fill'd with Water, and well stopp'd, into our Receiver; and, upon an Exsuction of the Air, found no sensible Alte∣rations; but another, which was not so close stopp'd, being put in, we observ'd that the Air included in the Bottle, upon the Surface of the Water, making it's way out, several Bubbles presently appear'd in the Bottom of the Water: from which Tryals, it appears, That whilst the Air was included, the Water appear'd as if press'd upon by the Atmosphere. But in order to a further Prosecution of our Design in this Ex∣periment, we fill'd a Glass-Egg with Water, and suspended it by a String to the Cover; so that, by turning the Glass-stopper in the middle of the Cover, we so screw'd up the Neck of the Egg, as to break it, and thereby make way for the Exclusion of the Air; upon which a number of Bubbles presently rose in the Water, so as to represent a Shower of Rain inverted. But this Experiment may be try'd with less trouble, in one

of our little Receivers, where the Exsuction of the Air is more expeditious. In one of which the Experiment being made with red Wine, in∣stead of Water, it appear'd immediately frothy, like Bottle-Ale, tho' open'd less cautiously.

EXPERIMENT XXIX.

* 1.93TO shew, whether the Ascent of Fumes and Vapours, was rather promoted by the Am∣bient Pressure of the Air, than that their Ascent depended on their own Positive Lightness; I conveigh'd a Certain Liquor which I had for∣merly made for other Purposes, into our Re∣ceiver; it consisting of Metalline Ingredients, which upon Unstopping of the Bottle, would emit copious Steams, like the Powder of Ala∣blaster; but upon stopping of it again, the Up∣per Part of the Bottle, as well as the Liquor, be∣came Transparent; and this Liquor being con∣veigh'd into our Receiver, with a Weight affix'd to the bottom of the Viol, to keep it from ris∣ing up, when the Cork was pull'd out, we ty'd a String to the Cork, and the other End to the Receiver; and having clos'd it up, and pump'd out the Air, we screw'd the Cork out of the Bottle, and observ'd, that tho' some Parts of the Air included in the Bottle, rais'd a few; yet the Fumes did not rise as when expos'd to the open Air, but lifting up themselves by their own Agi∣tation, rose to the Top of the Viol, and no higher, but ran down the outside of the Glass in Streams; which continued till the Ingress of Air was permitted to put a stop to that Phaenomenon; but as soon as the Bottle was taken out into the

open Air, Fumes plentifully rose as before: From whence it appears, that Steams in a Medium thinner than themselves, may tend downwards.

EXPERIMENT XXX.

* 1.94TO shew how much the Ambient Atmos∣phere, emulates the Nature of a fluid Body; We enclos'd a light Match, in our little Re∣ceivers; and when it was fill'd with Smoak, we took the Match out, leaving the Smoak behind, closing the Receiver again, to keep it from flying away; upon which, we observ'd, that the Smoak settling it self in the lower Part of the Receiver, so far emulated a Fluid, as to change it's Horizontal Superficies, as the Glass was variously inclin'd. As also upon a more vio∣lent Agitation of the Vessel, it was put into a Vibrating and Undulating Motion, as Liquids usually are, which it lost again by degrees. When the Key of the Stop-cock was turn'd, Part of it would flow out like Red Wine, out of a Bottle, when the Neck is inverted and im∣mers'd in Water; the Air gradually ascend∣ing into the Receiver in it's Room: Besides which Phaenomena it was remarkable, that a hot Iron being held near one side of the Vessel; the Smoak was presently rais'd in a Stream up to the Top of the Receiver, keeping distinct Su∣perficies, from the Air included in the Receiver, yet nevertheless upon a Recess of that Heat, it would again subside. And these things being consider'd, as likewise that there is a manifest Difference in the Weight of Proportionable Quantities, as to Extension, of other Liquors,

it may not be absurd to mention the Atmosphere, amongst others Liquids; especially since, besides what we have already taken notice of, we may rationally suppose, that there are several Ine∣qualities upon the Borders of the Atmosphere, as well as upon the Surface of that Smoak; since the Inequalities of it's upper Superficies are not altogether indiscernible, if we look upon the Setting-Sun, with a good Telescope; for by that means, we may perceive the Surface of it rough, with several Inequalities, which curl along like Waves in the Sea.

EXPERIMENT XXXI.

* 1.95TO try the Strength of the Air's Spring, when rarify'd, in a great Measure, by Ex∣suction, in our Receiver; we try'd an Experi∣ment, formerly more fully taken notice of, with two flat polish'd Marbles: For having fasten'd a Weight of about four Ounces to the lower, and wet the flat Superficies of them with Spirit of Wine, to keep the Air from getting betwixt them, we put them into our Receiver, and found that the Spring of the Air, after several Exsu∣ctions, was strong enough to bear up the Under∣stone, and to keep it from falling. And how strong the Cohaesion of Flat Bodies may be, we have a Notable Instance related P. Nic. Zucchius, apud Schot. Part. 1. Mec. Hydraulopneum, who says, Juveni lacertorum suorum robur jactanti proposita semel est laminea aerea, per ansam in medio extan∣tem apprehensam elevanda è Tabula Marmorea, cui optimè congruebat: Tum instantibus amicis manum utramque admovens, cum luctatus diu harentem re∣movisset,

excusavit impotentiam objecta peregrini & potentissimi glutinis Interpositione, quo fortissimè co∣pulante nequiret divelli; donec vidit ab alio per ta∣bulam facillimè laminam deduci, & ad extrema pro∣ductam, & actam in transversum inde deportari. But to make it evident, that two Bodies may stick together, by having their Surfaces Contiguous only in a small Compass, I shall subjoyn an Ex∣periment made in our Receiver.

EXPERIMENT XXXII.

* 1.96HAving exhausted our Receiver, and taken it off the Pump, we apply'd a tapering Valve of Brass, such as the Ninth Figure repre∣sents, the taper End being put into the Orifice of it, and the Chink betwixt the Stop-cock and the Glass, being fill'd up with Diachylon. To the lower Superficies of the Door of that Valve, was fix'd a Button, to which a Scale was hung, to hold Weights in; and then, the Key of the Stop-cock being turn'd, the Atmosphere made such a strong Pressure to get in, as to keep the Valve close to the Orifice, till a considerable Weight was put into the Scales, and then the Weight of the Atmosphere being overpower'd, it was pre∣sently drawn down. In which Experiment it was to be observ'd, That tho' the Receiver was but moderately exhausted, and tho' it leak'd conside∣rably; yet the Weight supported by the Pressure of the Atmosphere, amounted to ten Pound: Nor indeed is it strange, that it's Pressure should be so considerable, if we do but think, how large the Cylinder of Air, that recoiling from the

Ground, presses against it, is, being extended to the utmost Superficies of the Atmosphere.

EXPERIMENT XXXIII. Concerning the Pressure of the Air against the lower superficies of the Sucker, what Weight will draw it down, and how much it is able to raise. A Discourse concerning the Nature of Suction, &c.

* 1.97TO compute more exactly the Weight of the Incumbent Atmosphere, we impell'd the Cy∣linder to the Top of the Pump, taking off the Receiver, and fixing just such a Weight to one of the Teeth of the Sucker, as was able to bring it down to the Bottom of the Cylinder; which being done, and the Sucker impell'd up again to the Top of the Cylinder, the upper Orifice of it was exactly stopp'd; and a pair of Scales being fix'd to the Iron-Sucker, by casting in so many Weights, as were able to draw down the Sucker, we were truly inform'd of the Weight of a Pillar of the Atmosphere of an equal Diameter with the Bore of the Cylinder. By which Me∣thod we found, that the Sucker, which requir'd 28 Pound of Lead to draw it down, was not drawn down with less than the Addition of an hundred Pound, when the upper Orifice of the Cylinder was stopp'd; tho' upon turning of the Key of the Stop-cock, and letting in Air, it would readily fall without that Weight; which was an Argument, that the Descent was hinder'd by the Pressure of the Air, which buoy'd up against the lower Part of the Sucker.

* 1.98This Experiment being try'd, and the Sucker being forcibly drawn down to the Bottom of the Cylinder, whose Diameter was about three Inches; the Pressure of the Atmosphere was so considerable, as to be able to raise above a hun∣dred Pound weight; besides the weight of the Sucker, which was not a little admir'd by the Standers-by, because they saw no Force used to lift it up.

And tho' by such Tryals we may not be able to discover exactly the weight of the Atmosphere; yet, as a Famous Poet says,

Est quoddam prodire tenus, si non datur ultra.

But were this Experiment Try'd at several Seasons, in the Year, and in several Climes, as well as in Cylinders of a different Diameter, it might render our Guesses more certain as to the Height, and Gravity of the Atmosphere, and whether it varies considerably at such distant times: For the Place where the Foregoing Experiment was try'd, was about 51 Degrees Latitude, being try'd in the Winter, and about the Change of the Moon.

But, not to spend so much time, as would be taken up with all the Reflections, that might be made on the Foregoing Experiment; I shall con∣sider some few Inferences, which may be drawn from them.

And First, From the Rising of the Sucker, and the Weights fix'd to it, we may call in Question, what some teach concerning Suction, viz. That there is a sort of Endeavour, to draw the Body suck'd, in the Parts of that Body which is said

to suck; for tho' when we suck a thing with our Mouths, there is a Manifest Endeavour of our Mouth to draw the Body suck'd; yet the Cavity of the Cylinder is not so dispos'd by any Endeavour in the Glass-Tube. Nor can the Ascent of the Sucker be attributed to any sucking Force of every Part included in the upper Part of the Cylinder, since it appears not, how such Aery Particles should be hook'd in the Pores of the Sucker, or how they should be able to raise such a Weight: Nay, that those Particles of Air do not draw it up, is further evident; since by admitting more Air in, that supposititious sucking Qua∣lity is diminish'd, and not increas'd: And for the same Reason it is evident, that it cannot pro∣ceed from a fuga Vacui; for there is the same Reason for an Endeavour to prevent a Vacuum, tho' a little more Air be let in, as there was be∣fore; since there still remains a Vacuity. Nor can the weaken'd Attraction, upon letting in of Air, be attributed to the Resistance of the Va∣cuity, but rather the Spring of the included Air; since when in the former Experiment it was plain, that the rising of the Sucker and Weights, was not obstructed by the Cavity of the Cylinder, when void of Air.

* 1.99But to proceed: From hence further we may be directed, what to think of Nature's Abhor∣rency of a Vacuum, which hath been so long held as an Axiom in the Schools: For besides, that the Insensible Parts of Matter, can neither have Sense to perceive any ill consequences in the Universe, which would ensue a Vacuum, nor be able to know how as Intelligent Parts of Matter to prevent it; (for if they did, Nature may be said in a great

many Cases to act very irrationally to effect her Designs, since in the XXXII^d Experiment, instead of rushing into the Receiver, she less cautiously rais'd up the Valve, and kept her self out. But, I say, besides the Insensibility of Matter, it may farther be urg'd against that Axiom, that the Endeavour which those Bodies may seem to have, rather is to fill than to prevent a Vacuum; since upon the drawing down of that Valve, the Air which rush'd in, could not prevent what was al∣ready in Being. Besides in our XIX^th Experiment, it might be demanded, Why the Water which descended into the Tube, upon the Exsuction of the Air, did not rather keep it's place to prevent a Vacuum, or why for the same Reason it did not ascend before the Re-ingress of the Air.

Moreover, the Air may rather be said to rush in again, as being impell'd by the Spring of the Neighbouring Air, than a Design to fill the Va∣cuities, since from our XVII^th Experiment, it ap∣pears, That when the Receiver was suppos'd to be full, we could by the help of the Sucker, find the Spring of Subsequent Air impell'd by it, still force more into it; and even in Wind-Guns it is manifest, that the Air compress'd as much as it is in our Receiver, may be squeez'd into half the Room.

And from the foremention'd Experiments, it may further be deduc'd, That the Reason, why Metaphorically speaking, Bodies may seem to for∣get their own Natures, to shun a Vacuum, seems to consist in this, viz. that the Weight of the in∣cumbent Water, or the Pressure of the subjacent Air were not strong enough to press down or buoy up one another; for from our Nineteenth

Experiment it appear'd, that when the Pressure of the Air was taken away, the Weight of the Water it self was sufficient to make it subside, tho it left no Air behind it: But further, from this last mention'd Experiment it appears, that it is possible, Even by Weights, to measure how far Nature is dispos'd to prevent or fill Vacui∣ties; since a small difference in Weight deter∣min'd, by depressing or permitting the Sucker to rise, how far Nature's Abhorrency of a Vacu∣um depended on the Causes we have so often mention'd.

But here it may be requisite to advertise, that by Vacuities, I do not mean Spaces altogether void of Matter, but void of such as may be perceiv'd; so that I take the Word Vacuum in the Common, not the strict and Philosophical Sense of the Word.

But lastly, from this XXXIII Experiment it appears, that the Weight of the Atmosphere we live in, is stronger than what Men usually think it is; And probably, near the Northern Pole, it is much stronger: Since, if what Varenius observes, the Air is so condens'd in Nova Zembla, as to hinder the Motion of a Pendulum, except moved by a heavier Weight than what is usually made use of in our Climate.

EXPERIMENT XXXIV.

* 1.100TO try whether the Aequilibrium of two Bodies, of an equal Weight in the Air, but of unequal Dimensions, would be lost in our Receiver, as it usually is in Water, by Reason of a greater Quantity of Water buoying up a∣gainst

that whose Dimensions are most extensive, I took a Bladder half full of Air, and ty'd it to one end of our Balance, which turns with the 32 part of a Grain; which being counterpois'd with a Weight in the other Scale, we let it down into the Receiver, and having clos'd it up, upon an Exsuction of the Air, we found the Bladder to dilate and manifestly to preponderate; but upon admitting the Air into the Receiver again, the Bladder was over-pois'd by the Weight; but leaving them in the Receiver all night, the Bladder imbib'd so much of the External Moi∣sture, as to weigh that end of the Balance down a good way; yet the Bladder being dry'd a lit∣tle, they were both brought to an Aequilibri∣um: And the like Experiment we try'd with a piece of Cork instead of the Bladder, and ob∣serv'd, that, the Receiver being Evacuated, as well as upon a reingress of the Air, the Cork manifestly preponderated.

EXPERIMENT XXXV. Of the Cause of Filtration, and the Rising of Wa∣ter in the Syphons, &c.

* 1.101TO try whether in Filtrations the rising of the Water might not proceed from the Impulse of the Air; we made use of a Syphon of Glass, represented by the Third Figure, which is made of two strait Pieces, and a crooked one, which joyns the other two together, the Jun∣ctures being well clos'd. The longer Leg of the Syphon was pervious only at the small End, so as to suffer the Water to pass through it; but

both the ends of the shorter Leg were equally pervious, the Diameter of their Bore being ¼ of an Inch. The length of these two Pipes was about a Foot and a half, that the Rarifi'd Air in the Receiver, when it was pretty well exhausted, might not raise the Water included in the Pipe too high. The shorter Leg of the Syphon be∣ing immers'd two or three Inches in a Vessel of Water, the other end was fastned to the Cover; which things being done, and the Receiver clos'd up, we began to pump. The Result of which was, that the Water dropp'd out of the lower Leg of the Syphon, as if it had been expos'd to the open Air; till the Receiver was in some measure exhausted, and then several Bubbles ri∣sing in the Water, gather'd together at the Top of the short leg'd Syphon, where expanding themselves, they stopp'd the Course of the Wa∣ter; that in the longer Leg being suspended in the Tube and ceasing to drop; and the Water in the shorter Leg, was so far depress'd, as not to be above a Foot high: But as soon as the Exter∣nal Air was let in again, it enter'd in at the small Orifice of the longer Tube; and, ascending through the Water contain'd in the Pipe, joyn'd with the former, which was lodg'd in the upper Part of the short leg'd Tube.

But, to prevent what Inconveniences ensu'd the rising of these Bubbles, the two foremen∣tion'd Tubes, were placed so, as to meet in the middle of a Glass Viol, the Neck of the Viol being clos'd up with Cement; and the Tubes be∣ing thus fix'd, and they, as well as the Viol, fill'd with Water, the Syphon represented by the Fifth Figure was plac'd in the Receiver with its

shorter Leg in a Vessel of Water, upon which the Pump being ply'd, the longer Syphon con∣tinu'd to drop much longer than before; but at the last, the Bubbles which rose in the Pipes, were so dilated in the Viol, as to press down into the Ends of the Tube, and interrupt our Experiment, tho' what we observ'd gave us Reason to believe, that the Air contributed to the Motion of the Water through the Sy∣phons.

And here, I shall subjoyn, that I once had a very slender Pipe, which when held upon the Surface of the Water in a Perpendicular Posture, the Incumbent Atmosphere press'd so much more on the Surface of the External Water, than that contain'd in the Tube, that the Water was rais'd in the Tube; and this Pipe being bent into a Sy∣phon, and plac'd with the shorter Leg in Water as Syphons usually are, the Water, of its own accord, rose up in the shorter Leg, and ran down the other; and this Syphon being plac'd in our Receiver, to try what Alteration of the Phaenomenon would appear there, we could not dis∣cern any sensible one. But tho' in this Tube just now mention'd, the Water rises of its own ac∣cord; yet, if such a Tube be thrust a little way into the Mercury, instead of rising, the Mer∣cury in the Tube will be below that which is without it.

EXPERIMENT XXXVI. The Weight of Air in the Exhausted Receiver. The subtle penetrating Power of some Spirits above that of the Air. The Cause why Air will not enter the Pores of some Bodies which Water will. The Weight of the Air, examin'd by an Aeolipile. The Proportion betwixt the Gravity of Air and Water: Betwixt Water and Quicksilver. Con∣jectures concerning the Weight of the Atmo∣sphere.

* 1.102NOtwithstanding the several Methods pro∣propos'd by Galileo, and others, to try the Weight of the Air; being willing to be fur∣ther satisfi'd, we caus'd an Oval Glass with a small Tube at one End to be blown at the flame of a Lamp. And this Glass Bubble, being of the size of a Hen's Egg, was fix'd to one End of a Balance, being counterpois'd by a Weight at the other End, which being suspended in our Receiver, and the Pump set on work, the Bub∣ble, after three Exsuctions, continu'd to prepon∣derate more and more, till the Air was let in again, and then the Balance was reduced to its former Aequilibrium. But having repeated the Experiment with an additional Weight of three Quarters of a Grain, in the Scale opposite to the Bubble, the Weight of the Air included in the Bubble brought the Balance to an Aequilibrium, when the Air was drawn out; which Aequili∣brium was again lost upon a reingress of it; so that had the Air been wholly exhausted, the Air contain'd in the Bubble might probably

have weigh'd a whole Grain; and to prove that the Weight of the Air did really depress the Balance to which the Bubble was fix'd, we ex∣hausted the Receiver when the Neck of the Bubble was open; and did not perceive that End of the Balance in the least to preponderate: But a Lamb's Bladder being equally pois'd with a correspondent Weight, manifestly weigh'd down the Balance, tho the Air included in it, was considerably expanded when the Air was pump'd out of the Receiver.

* 1.103But once having caus'd the Pump to be ply'd longer than ordinary, the Air contain'd in a Glass Bubble expanded it self so powerfully, as to cause the sides of it to fly in pieces; which is a strong Argument of the Closeness of the Pores of the Glass, which are too fine to per∣mit the Air to pass through them. And for a further Proof of the imperviousness of Glass, even by so minute Particles as those of the Air, I shall add; that in all the Tryals I ever made, I but once found that a Spirit whose Parts are much more subtle and volatile than Air; I say, I but once found that a Spirit drawn from a Substance abounding with volatile Salts, and subtle Spi∣rits, made way through the Pores of the Recei∣ver, which unusual Phenomenon probably de∣pended on the brisk Agitation of those spiritu∣ous Parts, encreas'd by the more than ordinary Heat with which they were rais'd; for the Mo∣tion of them was so violent, as to fill the Recei∣ver, and almost burst it with their impetuous Steams; so that the Pores of the Glass being open'd with the violent Heat, several of them

penetrated those Pores, and appear'd on the out∣side of the Glass.

* 1.104But tho' by some, the Particles of the Air are thought to be able to penetrate Glass; yet by o∣thers, they are thought to be Grosser than Wa∣ter; since from the following Experiment it ap∣pears, that Water is capable of penetrating Bodies, and of being compress'd into their Pores, which Air is not: For having conveigh'd a small Bubble of Water into the longer Leg of a Sy∣phon, whose Orifice was as small as a Pin, that Air being incapable of passing through so small a Pore, kept the Water above it, suspen∣ded in the Tube; but as soon as that Bubble, by blowing into the wider Orifice of the short Leg, was compress'd and squeez'd out, Water pass'd through that small Orifice without any other force than the Weight of that which lay upon it. And the Inability of Air to pass through such Pores, which Water will readily enough, will be further evinc'd, by holding Water in a Tube, the lower End of which being very narrow, and perforated with a Pore no longer than a Hair; for the Water will readily pass through it; but if the Tube be inverted, the Water in the narrower End of that Pipe will be suspended, as if the End were wholly unperfo∣rated; the Air not being able to get through so small a Passage: And that Water will pass through Pores, which Air will not, may be fur∣ther evinc'd, by putting a little Alkalizate Salt into a Lamb's Bladder; for by wetting the End of the Bladder on the outside, the Water passing through it's Pores, will presently dissolve that Salt.

* 1.105But to return to what we have hinted before, concerning the Expansion of Air in a Bubble, so violently, as to break it; the Learn'd Jesuit Cabaeus says, he saw a Pillar so thick, that three Men could not grasp it, and that 1000 Yoke of Oxen could not tear it in Pieces; yet the Air in∣cluded in the Crannies of it, so violently expan∣ded upon the burning of a Fire near it, that it flew in pieces, tho' the Pillar was made of so so∣lid Stones as Marble. And as for the Reason why sometimes the Bubbles included in our Re∣ceiver, did not break as at others, it probably pro∣ceeded from the Air's Expansion by Heat, when they were seal'd, the included Air, upon a Re∣moval of that Heat, contracting it self, and losing part of it's Springiness; but this Guess we can∣not wholly rely on. But,

* 1.106To determine more exactly the Weight of the Air, we heated an Aeolipile of Copper, as hot as we could conveniently; and removing it from the Fire, we stopp'd the Neck with hard Wax, to keep out the Air; which being Weigh'd, when cold, counterpois'd six Ounces, six Drachms and Thirty nine Grains; but the Air being permit∣ted to rush in, by perforating the Wax with a Needle, the Aeolipile and Wax balanced an ad∣ditional Weight of 11 Grains; so that the Weight of so much Air as fill'd the Cavity of it, weigh'd half a Scruple and a Grain. And tho' Mersen∣nus affirms, that he had rarifi'd the Air to seven∣ty times its Bulk in an Aeolipile, yet I must con∣fess it seems impossible to me, except the Metal his were made of, would bear a much greater Degree of Heat, without melting, than ours would, to rarifie, and expel the Air contain'd

in them: Besides, the Method he took seems much less exact than ours, since he weigh'd the Aeolipile whilst hot; which might throw off a Considerable Quantity of Scales, as we have often observ'd; the Weight of which, in weigh∣ing so light a Body as Air, might be considera∣ble.

* 1.107As for the Difference in the Weight of an e∣qual proportion of Air and Water, tho' Riccio∣lus and Galileo have, by different Methods, made very different Computations; and Mersennus hath asserted it to be as 1300 to 1. Yet by the most accurate Computation we could make in our Aeolipile the difference appear'd to be, no more than as 1 to 938. I shall not wholly reject what Mersennus relates, but rather endeavour to reconcile the Difference, by representing, that my Observations were not only made in this Climate in London, where it is much colder than at Paris; but also at a time, when the Air was condens'd by the Winter's Cold; at which time it may be suppos'd to be a fifth Part heavier than at Paris, when Mersennus made his Observa∣tions. Wherefore it would be of no small use, to make such Observations in several Countries and at several Seasons of the Year.

* 1.108Having said thus much about the Weight of the Air, it may perhaps be expected, that I should, by the Assistance of the Observations already deliver'd, determine the Height of the Atmosphere, from whence the Pressure of the Air proceeds: But tho' it may be no difficult Task to shew, that the Accounts given by others are false; yet it is not altogether easie to deter∣mine a Controversie, in which the Truth is so

hard to be assign'd; and therefore, I shall only lay down something in order to the Elucidation of it.

And first, it is necessary to take Notice, that the Weight of an equal Proportion of Air and Water about London is agreed on to be as 1000 to 1.

In the next place it will be requisite to consi∣der, the Difference in Weight, of an equal Pro∣portion of Air and Quicksilver; to discover which, I took a Glass Pipe, such as is represen∣ted by the Sixteenth Figure,* 1.109 which being partly fill'd with Quicksilver, and held in such a Po∣sture, that the Superficies of the Quicksilver in each Leg was in a Horizontal Line, E. F. I. pour'd Water into one Leg, till it was fill'd up to the Top, by the Weight of which, the Sur∣face of the Mercury was weigh'd down from E. to B. the Surface of the other being rais'd from F. to C. so that measuring the Height of the Tube of Mercury D. C. which was buoy'd up by the Water in the other, we found it to a∣mount to 2 13/54 Inches; the Height of the Cylin∣der of Water B. A. which counterpois'd the Mercury being 30 45/54 Inches, and the whole Num∣bers with the Fractions, being reduc'd to impro∣per Fractions of the same Denomination, the Proportion was as 121 to 1665, or by Redu∣ction, as one to 92/121.

Besides this, we took another Method, to di∣scover the Proportion of these two Liquors, by weighing them in a Glass Bubble; by which we found, that it was as 1 to 13 19/28; and because Spirit of Wine is usually esteem'd the lightest of Liquors, and Quicksilver the heaviest, I

weigh'd that likewise, and found the Proportion of Quicksilver, and it, to be as 1 to 16 641/1084. So that the difference betwixt Spirit of Wine and Water was as 1 44/171; And here it may be neces∣sary to observe, that I the rather weigh'd these Liquors in a Bubble; because, when they are weigh'd in open Vessels, the Protuberant Sur∣face of the Mercury, and the Concave of the Water, makes it a difficult Matter to propor∣tion them exactly, if the Superficies be large.

* 1.110But to return to the Atmosphere. Having laid down the Proportion of Air to Water, and of Water to Quicksilver, it will be no very diffi∣cult thing to find, the Proportion betwixt Air and Quicksilver. And since from the Torrecel∣lian Experiment, it appears that the Cylinder of Mercury is buoy'd up by the Pressure of the Air, it consequently follows, that the Proportion of Air to Quicksilver is as 14000 to 1; so that a Cylinder of Air, that is able to buoy up Mer∣cury two Foot and a half, must amount to 35000 Feet of our English Measure, or seven compleat Miles; supposing the Air to be equally com∣press'd above, as here below; but this Compu∣tation is not to be accounted so exact, since not only Seneca Nat. Quaest. lib. 4. cap. 10. says, Om∣nis Aer, quo propior est Terris hoc crassior; quem∣admodum in Aqua & in omni humore Faex ima est; ita in Aere spississima quaeque desidunt, but it like∣wise is a Consequence of the Air's Spring; since it must needs be considerably compress'd by the Weight of what lies upon it; besides, if we con∣sider, that the Air may be expanded by Heat, to near a hundred and fifty times its Bulk, it may not be improbable, but that the utmost ex∣tent

of the Atmosphere, may reach to some Hun∣dreds of Miles.

And this Conjecture may enable us to guess at the Height to which some Vapours may as∣cend, allowing what Emanuel Magnen a dili∣gent Mathematician observ'd at Tolouse in a clear Night in August; for as Ricciolus records it, Vidit ab Horâ undecimâ post Meridiem us{que} ad mediam Noctem Lunâ infra Horizontem positâ, Nubeculam quandam lucidam prope Meridianum fere us{que} ad Zenith diffusam, quae consideratis omnibus non poterat nisi à Sole illuminari; ideo{que} altior esse debuit tota Ʋmbra Terrae: And the same Author further says, Addit simile quid evenisse. Michaeli Angelo Riccio apud Sabinos versanti, nempe viro in Mathesi Eruditissimo.

But to conclude; It would be of no small Use in estimating the Height of the Atmosphere, were Observations of the Density and Rarity of the Air made upon several Parts and on high Mountains; but till by some Means or other, we can arrive at some degree of Cer∣tainty, as to the various Degrees of it's Rare∣faction above, it will be a hard Matter to de∣termine the Height of it.

EXPERIMENT XXXVII. Concerning Flashes of Light in the Receiver.

AT the first when our Engin was made, we observ'd, upon drawing down the Suck∣er, and turning the Key, several Flashes of Light in the Receiver; which would not ap∣pear, if the Window which fac'd North-ward

were darkned; and this Phaenomenon depended on so unknown Causes, that upon often re∣peated Tryals, I found, that sometimes it would appear and sometimes not; though for as much as I was able to perceive, there was not the least Difference in the Circumstances of these Tryals; which made it difficult to bring our Observations to any Rules about it, or to frame an Hypothesis to Account for the Cause; tho' the Validity of some Conjectures that have been made may be afforded by the fol∣lowing Tryals and Observations. For,

First, We found, That the Phaenomenon might as well be exhibited by a Candle-light or Day∣light, and however situated, so that the Rays of Light could but fall upon the Receiver.

Next, The Flash appears just when the Key is turn'd to let the Air out into the Cylinder; but the same Phaenomenon would appear in a small one upon drawing the Sucker hastily down, tho' the Key was turn'd before; and it was further to be observ'd, That the Flashes, which appear'd when first the Receiver began to be exhausted, were much stronger than when it was further evacuated.

And it was besides observable, That when the Experiment was made in the small Receiver, and the Sucker had not been long before well oyl'd; the Oyl, upon the drawing of it down, being put into Agitation, and divided into small Parts by the Attrition of the Pump, would rise into the Receiver like Smoak; which would likewise flow out of the Valve, when it was open'd on purpose; and these Fumes, if the Glass was held in a light Place, would in some

Measure appear luminous. And what was fur∣ther to be admir'd, was, That when the Flash was considerably great, upon the Disappearance of it, the Receiver would become opacous, lea∣ving white Steams upon the internal Superficies of the Receiver.

And now if it should be asked, Whence all these Phaenomena proceeded? We should pro∣pose the following Conjectures, viz. First, That had the Phaenomenon constantly succeeded, we should have suspected the seeming Light to pro∣ceed from some Refractions from the Glass darkned within by those white Steams. Se∣condly, That, since the Air abounds with Parts gross enough to appear in the Sun-beams, and to reflect the Rays of Light, which rise from Bonfires, the Reflection might proceed from some gross Airy Parts within the Recei∣ver. Thirdly, The Whiteness seem'd to pro∣ceed from the various Surfaces of the airy Parts, reflecting one upon another like Looking-glas∣ses, so as to represent each other contiguous; so Water or Eggs beaten to Froth, lose their Transparency, and appear white: But further having immers'd the Neck of our Receiver in Wa∣ter, and set the Pump on work; the Water being drawn in through a small Hole, had its Parts so bro∣ken, that the Receiver appear'd full of Milk rather than Water: And if a Piece of Crystal be thrown very hot into cold Water, it will crack, and having so many new Surfaces within appears white.

Which Things being consider'd and weigh'd, it may not be an improbable Guess, That the aforementioned Phaenomena proceeded from the Parts of the Air displac'd as to their Posture and

Situation, as, whilst in that Motion, to di∣sturb their former Continuity and Transpa∣rency.

And this Conjecture may be made probable by observing, That the more Air was included, the more conspicuous was the Whiteness; but more especially by this, viz. That having ex∣hausted the Receiver, and apply'd a Glass Bubble to the Hole in the Stop-cock, so that there might be a Communication betwixt the Cavity of the Receiver, and it, upon the Exsuction of the Air out of the Receiver, the Air in the Bubble was so disorder'd, by so sudden a Disilition of it's Parts, that it appear'd like Milk; but upon a sudden Re-ingress of the Air, became trans∣parent again.

But if it should be objected, That the White∣ness in Water turn'd into Bubbles may proceed from the Interposition of so Heterogeneous a Body as Air; I should answer, That I have in another Place mentioned two volatile Liquors, which being mix'd produce a white consistent Body, though both the Ingredients were trans∣parent.

But having convey'd some Smoak into our Receiver, and observ'd upon plying of the Pump, That the Air remaining in the Pump, became opacous; we suspected, that the Rea∣son why the former mentioned Light sometimes appear'd and sometimes did not, might pro∣ceed from some Parts of Matter swimming in the Air more at one time than another, which was dispos'd, more to cause such Reflections of the Rays of Light as to afford the fore-named Phaenomenon; which is rendred probable by

observing, That the Receiver appear'd opaque when the Smoak settl'd about the Sides of it; and it may further be illustrated by what we mentioned before of our smoaking Liquor, where the Corpuscles of it being put into a new Mo∣tion became opacous instead of transparent.

And if it should be asked, How the Air should abound with such various Parts of Mat∣ter? I must answer, That it is not an unusual Observation, That the Air undergoes several and very frequent Changes; for besides several Instances which might be added, the Learned Josephus Acosta observes, That in America, There are Winds which naturally trouble the Water of the Sea, and make it Green and Black; others, clear as Crystal. Besides we observ'd, That the Pen∣dula as well as Scales suspended in our Receiver, lost a great deal of their Brightness, upon draw∣ing out and letting in the Air. And I once made a Tincture of a certain Metalline Substance, which would become turbid and clear successively, for several times, for which strange Phaenomenon no Reason could be given.

EXPERIMENT XXXVIII.

* 1.111HAVING conveyed a Glass Vessel into our Receiver, in the midst of which was con∣tained a Cylinder filled with Water, and enclo∣sed with Snow and Salt, upon plying of the Pump, the Snow began to melt a little faster than we expected; and the Receiver being pretty well exhausted, the Water in the Cylin∣der began to freeze; so that, in a little time, the Surface of the Ice was above that of the

Water, in which the Snow and Salt was dis∣solved, and which swam about it. The Super∣ficies of the Water was concave, and being held betwixt the Eye and the Light, appear'd full of Bubbles.

And it is not a little strange, That there should be so powerful an Expansion in Water froze, as not only to burst Bottles in the Win∣ter-time, but, as I am inform'd, to separate the solid Parts of Metals; so that Bell-Metal having been expos'd to the Wet, and that Wet froze in the Pores of the Metal, it would fly in Pieces; and Cabeus in lib. 4. Meteor. Aristot. relates a no less memorable Account of Vessels made of Stone, which would fly asunder, upon the Expansion of the Moisture lodged in their Pores, and froze there. Where it is not a little strange, That Cold should by freezing Water, cause it to swell, whereas the Effect it hath upon the Air is manifestly to condense it.

EXPERIMENT XXXIX.

* 1.112HAving put the End of a Glass Tube into an Oval Glass, so that it almost touched the Bottom, we cemented it to the Neck of that Oval, and then, conveying about six Spoons full of Water into the Egg, we blew it so full of Air, as to force the Water into the Pipe, and to keep it suspended betwixt that Air shut up in the Viol and the external Air; this Wea∣ther-glass represented by the Fourteenth Figure, was plac'd in a small Receiver, at the upper End of the Tube, which was small, being permit∣ted

to stand about five Inches above the Cover, the middle of which it penetrated.

Upon pumping out the Air, it was to be ob∣serv'd, That the Water in the Pipe manifestly descended; which was an Argument that no Sen∣sible Heat was produced in the Receiver, by the Action of the Pump; since by barely applying my Hand to the outside of the Receiver, that gentle Warmth so far rarify'd the Air in the Egg, as to enable it to raise the Water in the Tube, much higher than it was depress'd, upon the Ex∣suction of the Air: Tho' we will not thence in∣fer, that the Cavity of the Receiver, was colder after than before the Air was pump'd out; since the Pressure of the Air in the Egg, together with the Weight of the Incumbent Atmosphere might, in some measure, cause the sides of the Glass to give way, for want of an equal Pressure of the Air on the Convex, and external Superficies of it; which Guess may seem the more probable, not only because the Springiness of Glass might contribute to the bending of it; but likewise since upon a Re-ingress of Air, the Water was rais'd up to it's former Height again.

But to return to our Experiment: From hence it appears, That if there be no Vacuum betwixt the concave sides of the Receiver, and the Su∣perficies of the Bubble, every Substance fine e∣nough to penetrate the Pores of Glass, hath not it's Parts in an Agitation, strong enough to pro∣duce Heat and Fire.

Besides the Former Experiment, having try'd what Effect the Exhausted Receiver, would have on Camphire, whose Parts are so fugitive as to fly away when put into Motion, by the Action

of Ambient Air, we found that it was not in the least alter'd.

EXPERIMENT XL.

* 1.113HAving conveigh'd a Flesh-Fly, a Butter-fly, and a Humming-Bee into our Receiver; the former presently dropp'd down from the Place she was walking on; and after a few Ex∣suctions, the Butter-Fly, which before flutter'd up and down, dropp'd down void of Motion, except a Tremulous one in her Wings. And the Bee in a little time, was wholly depriv'd of Motion: But whether the Falling of them de∣pended on the Thinness of the Medium, which was unapt for them to swim in or not, will ap∣pear from the following Experiment.

EXPERIMENT XLI.

* 1.114HAving conveigh'd a Lark into our Receiver, and clos'd it up; upon plying the Pump, the Bird presently began to droop, and when the Receiver was further exhausted, being first taken with violent Convulsions, and Tossing up and down the Cavity of the Vessel, it died with it's Back contiguous to the Receiver; it's Head directed down towards the Stop-cock, and it's Neck awry: And tho' at ten Minutes Di∣stance, after this Bird was clos'd up, the Air was again let in at the Stop-cock, yet did it not recover again. And the like succeeded upon In∣closing a Hedge-Sparrow, except that the Air being let in again, at the end of seven Minutes, it recover'd by degrees; but when it seem'd

able to fly away, the Receiver being again ex∣hausted, it died in five Minutes Time.

Having inclos'd a Mouse in our Receiver, it continu'd to leap up for some Time after the Air began to be exhausted; but in a little Time after that, it appear'd sick and faint, and very giddy, and at the last fell down dead; yet upon a Re-ingress of Air, presently recover'd; but the Air being again pump'd out, in about ten Minutes, it died moderately convulsive. And it was not only observable in this, but all the other Experiments of this Nature, that I try'd, that the Included Animals died convulsive.

And to make it appear, that in the Foremen∣tion'd Tryals, the Animals died for want of Air, and not by being chok'd up with Fuliginous Re∣crements; I inclos'd another Mouse in our Re∣ceiver, which, the Air not being drawn out, liv'd 3 Quarters of an Hour; but upon pumping out the Air, in ten Minutes, died convulsive. And another being left in all Night, was alive the next Morning, and had eat Cheese, which was, for Tryal's sake put in with him,

A Digression containing some Doubts touching Respiration.

HAving made these Experiments relating to Respiration, it may perhaps be expected that I should say something concerning the Use∣fulness of Air in Respiration. In doing of which, it is not requisite that I should take Notice of the Structure of those Parts, since they have been sufficiently describ'd already. Nor shall I any further engage in that Controversy, Whether the Motion of the Lungs depends on the Motion

of the Thorax, or not, or how the Lungs are di∣stended by the Air, any further than it may be Illustrated by our Engin.

As for the First Part of the Controversy, it seems to be determin'd in favour of the Affirma∣tive, by what the Learned Dr. Highmore, and Bartholinus have observ'd; the former having taken Notice, That the Lungs subside, if the Intercostal Muscles be so wounded, as to lay the Thorax open; and the latter having observ'd the same upon a Division of the Diaphragm: But what it is that conveighs the Air into the Lungs, is yet undetermin'd; since some think it to pro∣ceed from the Dilatation of the Thorax impelling the Air contiguous, and what it contiguous to that, successively into the Lungs: But this Supposition is fairly answer'd, since it is possible to breathe out of a Glass, where the External Air press'd on by the Thorax, can only press on the outside of the Bottle. But a more easy Solution may be taken from our Engin, since it appears, That if the Lungs be dilated by the Thorax, the Spring of the Air is sufficient to force it in, there being less Resistence made by the Rarify'd Air in the Lungs, than that in the open Atmosphere. And tho' there are some Observations, which testify, that when the Diaphragm hath been considerably wounded, without damaging Respiration, yet since the Lungs are void of Musculous Parts to dilate themselves, we are rather inclin'd to be∣lieve that they are dilated by the Expasion of the Thorax, and fill'd by the Gravity, and Pressure of the Atmosphere.

But to proceed to the Use of Air in Respira∣tion, besides the Usefulness of it in Modulating

Sounds, and the Conveying of Odours, it is beyond Doubt, That it is in a great Measure ne∣cessary to the Preservation of Life, tho' as to the Manner of it's Contributing to the Continuance of Life, several disagree; since it is by some thought only to keep the Blood from growing too hot in the Ventricles of the Heart. But that this is not all that the Air, in Respiration, per∣forms, is evident, since not only Old People, but several Creatures, have no need of Cooling their Blood and Humours being cold enough without it, yet they cannot live without Respiration.

Others hold that the Air being convey'd into the Left Ventricle of the Heart, contributes to the Generation of Spirits; but since there ap∣pears no such Passages, as are fit for it's Con∣veyance, we shall not here recite what other Ar∣guments might be alledg'd against it.

But others, as Moebius and Gassendus, are of Opinion, that it chiefly serves to Ventilate and Carry off the Excrement of the Blood; for as a Candle may be extinguish'd by it's own Smoak; so the Heat of the Blood might be prejudic'd, were not it's Fuliginous Recrement carry'd off, by mixing with the Air upon Inspiration. Which is Congruous enough, to what hath been observ'd by several Travellers; viz, That there is a certain Consistence requisite in the Air, to carry off such Fumes; for it is observ'd, That if the Air drawn in, be too much impreg∣nated with Vapours, as in some Cellars, when Damps arise in Mines, it becomes so unfit to Breathe, as to stifle those that do not avoid the Latter, or use some Method to rarify it, as by holding a Chaffing-dish of Coals near

their Faces, to disperse and scatter those Fumes. And to confirm these Observations, I shall add, That having clos'd a Bird in our Receiver, I observ'd, that the Air being thicken'd by fre∣quent Respirations, it began in a little time to pant and gape, and at the last grew so sick, as to throw foul Matter off it's Stomach; and in 3 Quarters of an Hour to be ready to die: And that the Receiver should be so fill'd with Steams, needs not seem a Wonder, to any one that con∣siders, what Sanctorious hath observ'd, viz. That the greatest Part of our Aliment is carry'd off, by Insensible Transpiration.

And as these Instances shew, how unfit an Air too gross, is for Respiration; so that an Air too thin is likewise prejudicial, appears from the Ex∣periments already try'd in our Receiver; so that it is not Improbable that if a Man were remov'd to the Top of our Atmosphere, he would die for want of Breath.

In favour of which Conjecture, I shall add, That the Learned Josephus Acosta, tells us, that going up a high Mountain in Peru, call'd Pariacaca, which was so high above the Alps, as to make them appear only as high Towers, he and his Companion were taken with excessive Vomiting, together with Blood, which lasted till he came to a Region more convenient for Respiration; and he likewise says, to our present Purpose, That the Element of the Air is so subtle and delicate there, that it is too fine for a Man to breathe in; the Action of Respiration, requiring a grosser and more temperate Air.

But tho' from hence it appears, that the Air contributes to Respiration, in carrying off the

Recrements of the Blood; yet it is scarce pro∣bable, that those Recrements should so soon kill an Animal, as to cause Birds inclos'd in our Re∣ceiver, to die in a few Minutes, for want of be∣ing carry'd off. And it would not be harder to account for such Effects, should we allow with Paracelsus, That Air contributed to the Gene∣neration of a Vital Spirit; since the Interruption of it's Generation, for so small a time could scarce be fatal.

Yet I shall add on this occasion, That I have been told, that Cornelius Drebellus, made a Boat for the Learned King James, which would swim under Water, in which, to make the Air inclu∣ded fit for Respiration, he was wont to open a Vessel which contain'd a Liquor, which added such a Vital Spirit to the Air, as purg'd it of the grosser Exhalations, and condens'd them. Where∣fore I am the more favourably inclin'd to think that the Air may conduce to the Preservrtion of Vital Spirits; and that it contributes to the Pre∣servation of Life, as Air to Flame; for having con∣vey'd rectfy'd Spirit of Wine into our Receiver, we found, that it would not continue long, no more than the Vital Flame of an Animal, if the Air was exhausted.

But not to insist upon these things, we shall add, That having dissected a Bitch, and taking out one of the Whelps, tho' we open'd his Ab∣domen, and Thorax, and divided the Diaphragm; yet having once began to breathe, his Heart con∣tinu'd to beat above six Hours; whereas three more, which were involv'd in the Secundines, in the mean time, were all dead; tho' they were neither wounded, nor had ever breath'd. How far

this may serve to illustrate the Problem propos'd by Dr. Harvey, viz. Why a Foetus may live lon∣ger before it hath breath'd, if involv'd in the Se∣cundines, than if, when it hath once respired, Re∣spiration be stopp'd, we leave others to judge.

Whether Fishes breathe or not, under Water, especially those that want Lungs, I cannot now determine; but that Air is necessary to the Pre∣servation of their Lives, seems to be evinc'd, by observing, that if Fishes be inclos'd in a Bottle, which is close stopp'd from the Air; or if they be kept from the Air by the Freezing of Water, they presently die. And indeed, considering how many Particles of Air are interspers'd in the Pores of Water, it may not be altogether impro∣bable, that part of it is separated, as it passes through their Gills, or some other way: And I am the rather inclin'd to believe it, because ha∣ving put a large Eel into our Receiver, upon exhausting the Air, she turn'd up her Belly, and lay as dead, till the Receiver being un∣stopp'd, and the Fish taken out into the open Air, satisfy'd us of her Recovery, by very brisk and vivid Motions. But what is not a little to be admir'd, having put a Gray Snail into our Receiver, we perceiv'd not the least Alteration, when the Air was drawn out; but whence these Phaenomena proceeded, we shall not now stay to determine.

Nor are we now at leisure to examine any further, whether the Paradox which some hold, be true, viz. That the Child respires in the Womb; only we shall say that it is not altoge∣ther Fabulous, That the Foetus hath sometimes been heard to cry in the Womb; and Chickens

have been observ'd to pip in the Egg-shell, be∣fore it was broke; which may be Arguments of an obscure Respiration, except it can be made to appear, That such Sounds may arise from Ha∣lituous Vapours in the Larynx; and that they may, will not be a little favour'd, by observing what audible Sounds arise from the Halituous Vapours of an Aeolipile forc'd upon the Blade of a Knife, held in various Postures.

But to proceed, the Necessity of Breathing, tho' those that are not well are accustom'd to want it, may appear, from the small time, that such Men are able to stay under Water; but may further be illustrated by the following Experi∣ments: For having convey'd a Humming-Bee, a Flesh-Fly, and a Palmer-Worm, into our Re∣ceiver, upon the Exsuction of the Air in a Mi∣nute's Time, they all seem'd dead; but pre∣sently recover'd by the Re-ingress of Air; yet when the Air was again drawn out, they ap∣pear'd dead, which is a strong Argument to in∣duce us to believe, that the Bodies of Animals are but so many Curiously-contriv'd Engins, ex∣cept those of Men, whose Wheels are set on go∣ing, by the Influence of External Agents; for even those Flies, which presently die in our Re∣ceiver, will crawl about, even when their Heads are cut off. And it is not unworthy our Obser∣vation, That Insects which want Lungs, are no less sensibly affected upon the Exsuction of Air, than some that have them, which may be Grounds for a Suspicion, that the Particles of the Air enter in at their Pores, and that it keeps them alive by a Universal Perspiration.

But to put an End to this Digression: Tho' the Foremention'd Experiments have given me cause to suspect, that the Depuration of the Blood, is the chief Use of Respiration; yet since I believe it hath some other Uses, which are not yet explain'd, I shall conclude with that Saying of St. Austin's; Mallem quidem eorum quae à me quaesivisti, habere Scientiam quam Ignoran∣tiam: sed quia id nondum potui, magis eligo Cau∣tam Ignorantiam confiteri, quam falsam Scientiam profiteri.

EXPERIEMINT XLII.

* 1.115HAving fill'd the third part of a Long-neck Viol, with ten Sprigs of Coral, and as much Spirit of Vinegar, as swam about an Inch over them, we plac'd it in our Receiver; and tho' at the first there appear'd but very few Bubbles, yet upon a few Exsuctions of the Air, they rose so plentifully, as to make the Menstruum appear white, the whole continuing to boil and fer∣ment, as in a Seething-pot, as much Froth stand∣ing upon the Liquor, as answer'd the Depth of it, in the Viol: Yet upon letting in the Air, the Froth presently disappear'd, and the Liquor be∣came transparent again. And these Phaenomena successively follow'd each other, no less than five times, as the Air was drawn out, or let in again; and the Ebullition in those Tryals, upon the drawing out of the Air, was so great sometimes, as to run over the Top of the Glass; and that those numerous Bubbles might not be suspected to arise from the Spirit it self, we clear'd it of those, before the Coral was put in, but the same

Phaenomena, still succeeded: nor was there any considerable Difference, when the Tryal was made with Powder of Coral, except that the Li∣quor was obscur'd by several Parts of it carry'd up along with the Bubbles. But one thing in the Foregoing Experiments, was remarkable, That tho' the Ebullition was so violent, yet the Viol immediately taken out of the Receiver, did not affect our Hands with the least sensible Heat.

EXPERIMENT XLIII.

* 1.116HAving clos'd in our Receive a Viol of four Ounces fill'd with hot Water, which had been freed from Air by boiling, we pump'd out the Air, and observ'd, That upon the fourth Ex∣suction, it began to boil, as if it had been over a hot Fire, so that part of it ran over, and conti∣nu'd boiling in our Receiver. And what was more remarkable, was, that as often as the Air was let out of the Receiver into the Pump, the E∣bullition was again renew'd, the Fiery and Agi∣tated Parts of the Liquor, upon a Removal of the Air's Pressure, having more Liberty to expand themselves. And that the Phaenomenon was pro∣moted by the Removal of that Pressure, we may guess, because the Ebullition was only in the Top of the Liquor; and that it was renew'd upon a Removal of that Pressure. But especially, be∣cause Sallet-Oyl, whose Parts adhere, by Reason of their Clamminess, would not ferment; yet Oyl of Turpentine, or Wine would, whose Parts are not so tenacious; the former rising five times its Height, and near four Parts of the latter running over into the Receiver.

From all which Experiments it appears, that the Air may have a considerable Influence on a greater Number of Phaenomena than Men usually think of, especially where the tumultuous Agi∣tation of the Parts of a Body are concern'd; so that were a hot Body convey'd above the Atmosphere, the Effects of it would be different from what they are here below, and the Parts of it would have more Power to dissipate them∣selves.

Having thus far, My Dear Lord, given you a faithful Historical Account of the Productions of your Lordship's Commands, if they may in∣vite you or your Friends at Paris to a further Prosecution of what Discoveries may be made by that Engin, I hope they may afford your Lord∣ship as much Pleasure as they did me in endea∣vouring to express my self,

Your Lordship's Most Obedient Servant, &c.

CHAP. XIV. The Doctrin of the Spring and Weight of the Air defended against Franciscus Li∣nus.

THIS Chapter containing the Honourable Author's Vindication of his own Hypothe∣sis, concerning the Weight and Spring of the Air: It will not be requisite here to lay down, all the trivial Objections of Franciscus Linus; which are easily answer'd, by any one that hath but read and consider'd the Author's Hypothesis, and will at the first sight appear to be ill-ground∣ed or invalid Arguments, or rather false Criti∣cisms: But, it being more consistent with the design'd Epitomy, I shall only take notice of such, as may serve to illustrate the Hypothesis al∣ready laid down, and think it unnecessary to fill an Epitomy with, what our judicious Author did not repute as Arguments against his Doctrin: And especially, because the Learn'd World, by their General Consent have agreed upon what the Ho∣nourable Author hath taught: Wherefore I shall lay down only those Objections which may seem considerable, and annex their Solutions.

* 1.117The first Argument alledg'd by Franciscus Li∣nus, is, That, did the Suspension of the Mer∣cury in the Cylinder, depend on the Aequilibri∣um of the Weight of the Atmosphere; when a Cylinder is fill'd full and inverted, upon an In∣version of the Tube, and a Subtraction of the lower Finger, the Mercury would not subside,

were its descent not promoted by the Dila∣tation of the Air above the Mercury; for if it were, that Expansive Force would raise the Finger upon the upper Orifice of the Cylin∣der.

To which is answer'd, That the included Air may depress the Mercury by it's Expansion down∣wards, without raising the Finger; for the Weight of the whole Cylindrical Pillar of the Atmosphere, which presses upon the top of the Finger, being too strong to be overpower'd by the weak Expansion of the Air in the Pipe, it must consequently press downwards, where the Weight of the Mercury is ready to joyn with it to over-balance the Pressure of the Air, which before buoy'd it up: And that the Weight of the Cylinder of Mercury disposes it to spend its expansive Force downwards, appears from a Cylinder of Water suspended instead of Mer∣cury; for the Weight of that being not able to resist the Pressure of the Atmosphere downwards, equally as the Mercury; the Air in the Top of the Cylinder does not press it down near so far: And tho' the Objector says, that if Water in∣stead of Air be above the Mercury, it will not subside; the Reason of that is only, because the Water wants a Springiness to expand it self: And as for the Reason why the Pulp of the Finger seems to be drawn down into the Tube, that on∣ly happens, by Reason of the Weight of the Incumbent Atmosphere, the Rarifi'd Air within, not being able to make an equal Resistance to prevent the Finger from being press'd into the Pipe: And tho the Objector further urges, that he cannot conceive how the Air can be so expand∣ed

without possessing a greater Space, we have sufficiently clear'd that, by comparing the Ex∣pansion of the Air's Spring to a piece of Wooll squeez'd together, which when it is no longer Compress'd, dilates it selt by Virtue of its springy Parts.

* 1.118The second Objection is, That if Mercury be suspended in a long Pipe, about 40 Inches long, when the Tube is inverted, and the Finger is taken from the lower Orifice, it falls down till it comes to its usual Station; and the Pulp of the Finger is equally depress'd into the Tube; which evinces, that the Mercury is suspended by a Funiculus, which draws down the Pulpy Part of the Finger.

But, what Answer is to be given to this Ob∣jection, [Answer'd.] appears from what hath been said to the former; for the Mercury subsiding, till it came to an Aequilibrium with the Atmosphere; the Air above it being very much Rarifi'd, and unable to buoy up against the Finger; the Depression of the Pulp of it must proceed from the Weight of the incumbent Atmosphere, tho' the swelling of the Pulp in the Pipe might perhaps partly pro∣ceed from an Expansion of the Humours within the Substance of it, the Weight of the Atmo∣sphere being prevented from squeezing upon it by the Equivalent Weight of the Mercury.

* 1.119Another Objection is, That if a Tube twen∣ty Inches long, be immers'd in Quicksilver, and when it is full, the upper Orifice of it be stopp'd with ones Finger, as well as the lower, upon taking away the lower Finger, the Pulp of the upper will be drawn down, tho' the Weight of the Atmosphere is said to be able to buoy up a Cy∣linder

much longer; So that this is a plain De∣monstration of the Suspension of the Mercury by a Funiculus, and that it is not buoy'd up by the Pressure of the Atmosphere according to the Elaterists.

But tho' this Objection may seem to represent some Difficulty, yet it will easily be answer'd, by thus explaining the Phaenomenon, viz. Tho' when the Tube is stopp'd at both Ends, the Finger upon the Top of the Tube be e∣qually pres'sd upon on both sides; yet, upon a Removal of the Finger below, tho' the Pressure of the Air upon the Finger continu'd to be the same, yet the Pressure of the Mercury is by two Thirds less, against the Pulp of the Finger, its Gravity pressing upon the subjacent Air; for notwithstanding the Air is able to buoy up a greater Quantity, yet that in Part takes off the full Pressure of it, so as to make the Pressure upwards, disproportionable to that which tends downwards: And tho' the Objector urges, that the Mercury is equally suspended upon a Remo∣val of the Finger, as before; I answer, that the Finger presses it up much more strongly, to pre∣vent any of it getting out; whereas the Pressure of the Air only depends on the Weight of it, which cannot be intended or weaken'd, as that of the Finger may, which is capable of raising a much greater Weight.

* 1.120Another Objection alledg'd by the Author is, that were the Mercury buoy'd up by the Weight of the Atmosphere, it would be as easy to suck up Mercury in a Pipe as Water, nothing more being requisite but to draw away the Air.

But this may easily be taken off by consider∣ing, that the Dilatation of the Lungs depend∣ing upon an Ingress of Air upon the Motion of the Diaphragm and Intercostal Muscles, and that Air being press'd in by the Gravity of the Air and it's Spring, it will follow, that that Gravity or Spring being more powerfully re∣sisted by the Cylinder of Mercury than Water, the Lungs cannot so powerfully dilate; nor can the Mercury be rais'd with equal ease, because, that Air in the Lungs, together with the Weight of the Mercury, brings the External Force of the Atmosphere nearer to an Aequilibrium. Be∣sides, the External Air pressing upon the Thorax, and keeping them from dilating themselves, the Air contain'd in them, pressing against the Su∣perficies of the Mercury in the Tube, is a fur∣ther Cause, why it rises not so high; which Ex∣planation is confirm'd by observing, that as the Lungs are more violently dilated, the Mercury rises higher in the Tube; and it will be further Probable, by considering, how much greater a Pressure may be made upon so large a Superfi∣cies as that of the Thorax, than can be resisted by the Rarifi'd Air in the Lungs. And as for the Funiculus, which our Author supposes to raise the Mercury, by contracting it self; it would not be a little strange, that it should raise such a Weight as a Cylinder of Mercury, without tear∣ing off the thin Membranes of the Lungs to which such a Funiculus must, at one end be joyn'd.

To these Objections the Author adds an In∣ference, that if the Spring of the Air be of no Force, in loco aperto, no more can be effected by

it in loco Clauso; but the Place which the Obje∣ctor takes to be in loco Clauso, appearing to be only in a Room; It is answer'd, that whereas the former Objectoins appear to be invalid, the Inference must be so too; because there be∣ing a Communication betwixt the Air in a Room and the External, by some Holes or Crannies, or otherwise, the included Air will be able to do as much by its Spring, within as without.

CHAP. XV. The Funicular Hypothesis Examin'd.

THE Hypothesis laid down by our Adversa∣ry, and which is now to be examin'd,* 1.121 is, That what we ascribe to the Spring and Weight of the Air is done by a sort of Funiculus, con∣sisting of a thin Substance powerfully expanded, which being betwix two Bodies, endeavours to contract it self, and to bring those Bodies toge∣ther, ne detur Vacuum.

The first Argument alledg'd, is, That the Finger would not be so drawn down by the De∣scent of the Mercury, were there not a Funicu∣lus; and that were there not a thin Substance there extended, there would be a Vacuum,

As to the first Part of the Argument, it hath already been answer'd in the foregoing Chapter. And tho' he alledg'd the Necessity of such a Fu∣niculus from Nature's Abhorrency of a Vacuum; the first Argument he offers, being deduced from the Suction of the Pulp of the Finger upon the

Descent of the Mercury, It is likewise already An∣swer'd by what hath gone before in Explaining that Phaenomenon. But another Argument he alledges against a Vacuity is, the Diaphaneity of that Part of the Tube; for were there a Vacuum, he says it would be like a black Pillar, neither capable of affording any thing visible, nor of permitting visible Objects to appear through it: But the Invalidity of this Argu∣ment will appear from the Doctrin of the Epi∣cureans and Atomists, who Teach, that Light is made up of such subtle Emanations, as are capa∣ble of penetrating Glass it self, and tho' the Cavity of the Cylinder may seem full of Light; yet no doubt, but were the Parts of luciferous Matter condensed into a Lump, they would not fill half the Cavity; since the Smoak which fill'd up the Cavity of our Receiver, so as to make it appear Opa∣cous, was but capable of filling a small part of it, when condens'd. Besides, should the Torre∣cellian Experiment be made in the Dark, a Va∣cuist might argue, that the Matter, which upon an Access of Light was visible, was not in the Receiver before, but proceeded only from the Rays of Light darting through the Glass: And tho' Light should not be caus'd by a Trajection of such luciferous Beams, but from an Impulse of luciferous Bodies; yet would it not thence follow, that the Tube was full; since from our seventeenth Experiment it appear'd, that when the Receiver was in a great measure exhausted, there remain'd a sufficient Quantity of Matter behind, to communicate a tremulous Motion to the External Air: And tho' it should be allow'd, that the Cavity of the Tube were fill'd with the Car∣tesian

Materia subtilis; yet, since they allow that capable of passing in and out upon the Access of a grosser Body, it would not be any more to his Purpose, in maintaining his Funicular Hypothesis or opposing Ours, because such a Body as so ea∣sily passes in and out, will be as ready to give way to the Motion of a more gross Body, and con∣sequently to the rising or subsiding of the Mer∣cury.

Another Argument alledg'd in Favour of the Funicular Hypothesis, is, that when the Mercury is subsided to its wonted Station, it gravitates no farther. But it being already shewn, why it does not, viz. because it is counterbalanc'd by an equal Weight or Pressure made by the Atmo∣sphere, what hath gone before hath been a suffi∣cient Answer. And if it should be ask'd, why, when the Finger is press'd upon, by a Cy∣linder of the Atmosphere, and at the same time by a Cylinder of the Mercury on the other fide, it feels no sensible Pain; it may be answer'd, that the Pressure being equal on each side, the Sense of Pressure is the less perceptible; which is confirm'd by what divers observe at a considera∣ble depth under Water, viz. that they are not sensible of it.

And if it should be further ask'd, why upon the Descent of the Mercury, it, at the first, falls some∣thing below its wonted Station, and presently rises up again, it may be answer'd, that that proceeds from an Impetus acquir'd by its De∣scent, which at the first partly overpowers the Spring of the Air below it; but that Impetus being quash'd, the Spring and Weight of the Air presently weighs it up again to its usual Sta∣tion;

and having been put into a little more than ordinary Compression, raises it something higher; so that the Impetus upon a second De∣scent brings on a successive Elevation, till at the last the Impetus on each side gradually is lost, and discontinues that vibrating Motion; and this may not only be illustrated by the successive Vibrations of a Pair of Scales put in Motion by depressing one and elevating the other; but was farther confirmed by Mercury in a Glass Tube, made use of in our 36th Experiment, for ha∣ving put a Quantity of Mercury into it, and by inclining of it permitted it to run into one Leg, I stopp'd the Orifice of the other with my Fin∣ger, upon which, the Tube being erected, the Air contained in the Syphon, which was stopp'd at the Top, depress'd the Mercury in that Tube; but as soon as it was unstopp'd, the vibrating Motions of the Mercury began and continu'd to rise and fall successively for some time.

CHAP. XVI. A Continuation of Objections against the Funicular Hypothesis.

BESIDES the forementioned Objections, there are several others which perplex the Funi∣cular Hypothesis: As first, How the superficial Parts of two solid Marbles, which adhere toge∣ther, when exactly polished, can be drawn out into a Funiculus; a Difficulty which does not at

all perplex our Doctrin. Besides, were the Funicular Hypothesis allowed, it might be que∣stioned, How it comes to pass, that Liquors whose Parts are not equally liable to be extend∣ed into such Funiculus's should exactly subside till Aequiponderant to 29 ½ Inches of Mercury, and no further; an Objection which our Doctrin admits not of, since not only from Wind-Guns, but our former Experiments, it appears too manifestly to doubt of the Air's Spring and Gravity.

Nor is the Author's strange Method of pro∣ducing his Funiculus less exceptionable; for he says, When the Mercury touches the Top of the Tube, upon it's Descent, it leaves it's Super∣ficies to stick to the Top of it, which is extended by the Weight of the Mercury, till it leaves another Superficies joyning to that; where it may be objected, That neither Sense perceives any such Thing, nor can it be made probable by Reason; it being impossible to con∣ceive, How the Superficies of a Body can be so extended as to become a Body it self: And should it be allowed, that the Funiculus might be turned into so subtle a Body, it would be altogether inconceivable how it should be so firm and strong, as to suspend the Weight of a Cylinder of Mercury; and that it should have such an admirable Property as to extend without being made thinner, contrary to the Nature of all Ropes.

Besides, the Method he takes to illustrate his Generation of the Funiculus, by comparing it to the Flame of a Candle, does not enforce the Belief of it any more; for not to urge, That

the Parts of a Candle, are by Agitation, and a powerful Motion amongst each other, kept at such a distance, as to leave several and a Mul∣titude of Vacuities betwixt their Parts; if the Rarefaction of the Mercury in the Funiculus be like that, when it is rais'd in the Form of a Vapour, it would be too slight to suspend a Tube of Mercury. And it might be further demanded, How the Funiculus came by such Hooks, as to take hold of every Body contigu∣ous to them, so firmly, as to be able to break strong Glasses, by drawing their sides inwards; and how Fluids should be so suspended, as to appear one entire Piece, contrary to what their Fluidity disposes them to do. Nor is it less strange, That our Objector should allow this subtle Body a Spring which he denies to be in Air; since Nature's Abhorrency of a Vacuum cannot be the Cause of it, in as much as a Va∣cuum would not ensue, according to his Doctrin, tho' it were not contracted.

Moreover, it would not be a little hard to conceive, were such a Funiculus allowed of, how the Surfaces of Marbles extended, could contract into Marbles again; and how in the Cylinder of Mercury, the Funiculus is so easily relaxed, upon an Admission of Air into it, since, it filling up all the Space above the Mer∣cury before, it cannot easily be conceiv'd how it should be dispossess'd of that Space, without being thrust into another.

Again, I should be glad to know, if the Ca∣vity of our Receiver, upon an Exsuction of Air, were fill'd with such stretched Strings, it would be possible for a Pendulum to move in it without

breaking them; but our Author's Funiculus being made up of Strings, endued with pecu∣liar Qualities, we shall decline making any more Objections, since these Peculiarities may be sufficient to distinguish it from Truth.

CHAP. XVII. The Aristotelian Rarefaction Examined.

* 1.122BESIDES the former Objections which ren∣der the Funicular Doctrin unintelligible, there are yet others, upon the Account of the Doctrin of Rarefaction employed in the expli∣cating of it.

For the Doctrine of Rarefaction made use of by our Author, supposing a Body not only to fill up a larger Space, when rarified, but likewise so to fill it, as not to leave the least Vacuities betwixt it's Parts; it will be very hard to conceive, How a Hundred Parts of Matter, which are circum∣scribed by so many Spaces of the same Extenti∣on with themselves, should be capable of filling up more Space adaequately than they are circum∣scribed by, without the Addition of other Mat∣ter; and it seems strange, That without the im∣mediate Act of Omnipotence, Matter should be so extended as without any Addition to alter it's Dimensions.

And tho' our Author takes two Ways to ex∣plicate his Notion, either upon a Supposition of the Parts of Matter being indivisible or divisible in infinitum; yet, since he explicates it neither

of those ways so clearly, as to make it intelli∣gible, I must confess, I cannot acquiesce in them; nor are the Difficulties at all made less by asserting, That Matter may be virtually so extended as to possess more Space than is circumscribed by it; since a virtual Extension is as unintelligi∣ble as Extension without the Term virtually joyn'd with it; for since he seems to allow the Parts of Matter to be indivisible, it rather pre∣judices the Doctrin of Rarefaction as taught by Aristotle, than explains it; since it is incon∣sistent to think, That a Body, whose Parts are circumscribed by a certain Space, should fill a larger Space, without being divided and re∣moved out of the former.

Nor does it at all explain or render the Aristo∣telian Doctrin of Rarefaction, to say, That Matter may, by Omnipotence, be so ordered, as to possess adaequately double the Space it did before; since in Natural Philosophy it is not disputed what GOD can do, but what he hath done.

But besides the Difficulties in our Author's Doctrin of Rarefaction, there are no less in the Condensation which his Funiculus supposes; for since he allows of no Vacuities in it, it is impossible the Parts of it should be brought nearer than to touch one another, without a Penetration of Dimensions, which is wholly disallow'd of, and by no means to be admitted in Nature; for were that allowed, two or three Thousand Bodies might be contained in a Space, which every one of them by it self would fill; which is altogether unintelligible.

CHAP. XVIII. A Consideration concerning some Tryals of the Torrecellian and other Experiments' at the Tops and Feet of a Hill.

* 1.123FOr a further Proof against Our Adversaries Doctrin, and for a Confirmation of ours, I shall add the following Experiments.

And First: The Famous Pecquet mentions an Experiment, made by Monsieur Pascal, at the Foot of a Mountain 3000 Foot high; where when he ascended, 150 Fathom, the Mercury in the Cy∣linder was not buoy'd up so high, as at the Bot∣tom, by two Inches and a Quarter; and at the Top of the Hill, it wanted 3 Inches of that Sta∣tion, which it was suspended at, at the Foot of the Hill; which is a strong Argument against our Adversary; the Difference plainly appear∣ing to depend on the different Length of the At∣mospherical Cylinder, which was abler to weigh up the Mercury at the Bottom, than the Top of the Hill.

And Gassendus, Tom. 1. P. 211. relates, that the like was observ'd 5 times on the Hills at Auvergne. And a very Noted Virtuoso, Mr. J. Ball, as well as that Ingenious Gentleman Mr. Townley, have observ'd the like in England. And it was by the last nam'd, likewise observ'd, that the Mercury included in the Top of the Cylinder, was not able to depress the Mercury, near so much at the Bottom, as at the Top of the Hill.

But to discover the weight of the Air, and it's Spring, without going up to the Top of such high Mountains, we made use of the following Weather Glass, suspending Water in the Pipe, instead of Mercury. The Instrument was a Glass with a broad Foot, and a narrow Neck (A B), and a slender Pipe of Glass (C D), which was open at both Ends; and so plac'd, that the lower End was not far from the Bottom (A B), and was so closely cemented at the Neck (A),* 1.124 as to prevent the Internal Air (I I) from communicating with External (K K), unless it were through the Pipe (C D). And having conveig'd Water (H H) into the Glass (AB), which was pretty large, and having blown so much Air into the Bottle, as to raise the Water in the Tube above the Vessel, upon the Leads of Westminster Abby. When the Air was thought to be equally Cold and Con∣dens'd within the Bottle, as without; we mark'd the Station of the Water (F), and letting it down by a String to the Ground, the Water subsided an Inch, where it's Station (E), being mark'd, and the Vessel drawn up again, the Water was rais'd to the Mark (F) again. Which Experiment being again try'd, had the like success. And af∣terwards the Top of the Tube being broke, we let it down within the Church, the Surface of the Water in the Pipe being at (G) an Inch above the Water in the Glass; where I observ'd, that the Air so depress'd it, when it came to the Bottom, as to force the Water out of the Pipe into the Glass, several Bubbles breaking through into the Capa∣city of the Glass, and this Glass being drawn up to the Top of the Church again, the Water was manifestly rais'd in the Tube again; from whence

it appears, that the Atmosphere gravitates more; Caeteris paribus, the nearer the Surface of the Earth; for the Experiment being repeated, we found that as the Height, at which it was try'd, vary'd; so the Elevation or Depression did.

Another Particular which may be a further Confirmation of our Hypothesis, is, That which is mention'd by Monsieur Paschal, viz. That a Foot-Ball being weakly blown, and carry'd to the Top of a Hill, swell'd more and more, as it was carry'd higher; and as gradually grew lank, when it was carry'd down the Hill again: From whence it appears, That as the Atmosphere is lon∣ger or shorter, it makes a greater Gravitation and Pressure upon the Bladder.

To this I shall add an Experiment, sent to Dr. Croon, by a Learned Professor of Gresham Col∣ledge,* 1.125 which is the following: Having Observ'd that in the Weather-Glass (A B), represented by the Second Figure, which was about two Foot long; the Water was suspended in the Pipe, about thirteen Inches above the Superficies of the External Water, at the Bottom of Hallifax Hill; but being carry'd to the Top of the Hill, it sub∣sided an Inch and a Quarter, to the Point (D). The Internal Air (A C), which was taken in at the Bottom, dilating it self at the Top further by (C D). In which Experiment, the Descent being much more considerable than what it ought to be in such a small Ascent, by the bare Pressure of the Atmosphere diminish'd, the Reason appears to be, the Expansion of that Air included in the Top of the Weather-Glass; as well as the Short∣ning of the Atmospherical Cylinder.

CHAP. XIX. Experiments concerning the Measure of the Force of the Spring of Air, compress'd and dilated.

TO make it evident, That the Spring of the Air is able to do much more, than we have attributed to it, upon the Account of its Spring and Weight, we try'd the following Experi∣ments.

* 1.126Having pour'd Mercury into a Glass-Tube, which consisted of a Long Leg, and a Short One, which were so bent as to lye Parallel almost to each other; we pasted Papers upon each, which were divided by Marks into Inches, and each of those Inches into eight Parts; and upon pouring Mercury into the Longer Tube, we observ'd, That the Air contain'd in the Shorter, which was Hermetically seal'd at the Top, by twenty nine Inches of Mercury, was condens'd into half the Space it possess'd before; from whence it ap∣pears, that if it were able in so compress'd a State, by Virtue of it's Spring, to resist a Cylin∣der of Mercury of 29 Inches, besides the Atmo∣spherical Cylinder incumbent upon that, it fol∣lows, that it's Compression in the open Air, be∣ing but half as much, it must have but half that weight from the Atmosphere, that lyes upon it, in that Compress'd State.

But to be more exact,* 1.127 we took a Tube repre∣sented by the Fourth Figure, pasting upon the Shorter Leg a Paper, divided into twelve Inches, and each of those into Quarters; and another upon the Longer Leg, which made up several Feet, which were likewise divided into Inches, and those subdivided again into Quarters. The Tube being thus Mark'd, the Lower End was plac'd in a Wooden Box, that the Mercury might run into it, if the Pipe chanc'd to break: And one being assign'd to pour in Mercury at the Top of the Tube, another was plac'd to observe, when the Mercury in the small Tube, rose up to each of the Divisions, abovemention'd; and to take notice likewise, how high it stood in the Long Tube, at the same time, where the several Ob∣servations were set down, and are contain'd in the following Table.

A Table of the Condensation of the Air.

A	A	B	C	D	E
48	12	00	Added to 29 ⅛, makes	29 2/16	29 2/16
46	11 ½	01 7/16	30 9/16	30 6/16
44	11	02 13/16	31 15/16	31 12/16
42	10 ½	04 6/16	33 8/16	33 1/7
40	10	06 3/16	35 5/16	35 —
38	9 ½	07 14/16	37 —	36 15/19
36	9	10 2/16	39 3/16	38 ⅞
34	8 ½	12 8/16	41 10/16	41 2/17
32	8	15 1/16	44 3/16	43 11/16
30	7 ½	17 15/16	47 1/16	46 ⅗
28	7	21 3/16	50 5/16	50 —
26	6 ½	25 3/16	54 5/16	53 10/13
24	6	29 11/16	58 13/16	58 2/8
22	5 ½	34 15/16	64 1/16	63 6/11
21	5 ¼	37 15/16	67 1/16	66 4/7
20	5	41 9/16	70 11/16	70 —
19	4 ¾	45 —	74 2/16	73 11/19
18	4 ½	48 12/16	77 14/16	77 ⅔
17	4 ¼	53 11/16	82 12/16	82 4/17
16	4	58 2/16	87 14/16	87 ⅜
15	3 ¾	63 15/16	93 1/16	93 1/••
14	3 ½	71 5/16	100 7/16	99 6/7
13	3 ¼	78 11/16	107 13/16	107 7/13
12	3	88 7/16	117 4/16	116 4/8

• A, A, The Number of Equal Spaces in the Shorter Leg, which contain'd the same Parcel of Air diffe∣rently Expanded.
• B, The Height of the Mercury in the Long Tube, by whose weight the Air in the Short one, was com∣press'd.
• C, The Height of the Mercury, which coun∣terpois'd the weight of the Incumbent At∣mospere.
• D, The Aggregate of the Columns B and C, shewing what Pres∣sure was sustain'd by the Included Air.
• E, What that Pressure should be, allowing the Pressures, and Ex∣pansions, to be Reci∣procal Porportions.

But in Trying this Experiment, whoever pours in the Mercury, he must do it by degrees, and ac∣cording to the Directions of the other, that takes notice of the Ascent of the Mercury below; for if it be pour'd in without Caution, it may rise up

above the Marks plac'd on the Outsides, before due Observations can be made.

Having, by the weight of so vast a Cylinder of Mercury, compress'd the Air into a Quarter of the Space it possess'd before, we observ'd, tho' it could not be sensibly condens'd further by Cold, yet the Flame of a Candle brought near it, gave us reason to think, that a greater degree of Heat would have expanded it; but fearing the Cracking of the Tube, we durst not try it.

From the Experiment it appears, That as the Air is more or less compress'd, so it is able to counterpoise a Heavier or Lighter Cylinder of Mercury. And that the Mercury was born up by the Spring of that condens'd Air, appear'd by sucking up the Air out of the Tube, when the Mercury was 100 Inches high in the Pipe; for the Pressure of the incumbent Pillar of the Atmo∣sphere, being by that means taken off, the Mer∣cury was rais'd in the Long Tube, by the Expan∣sion of the Air in the Short Leg: And not by any Funiculus, since the Objector confesses, that cannot raise more than a Cylinder of 30 Inches.

* 1.128But, together with what hath been said, it may not a little illustrate our Doctrin of the Spring of the Air to observe, how much it's Spring is weaken'd, accordingly as it is differently Expan∣ded, and Rarify'd.

A Table of the Air's Rarefaction.

A	B	C	D	E
1	00 0/9	Substracted from 29 ¾, leaves	29 ¾	29 ¾
1 ½	10 ⅝	19 ⅛	19 ⅚
2	15 ⅜	14 ⅜	14 ⅞
3	20 2/8	9 4/8	9 15/12
4	22 ⅝	7 ⅛	7 7/16
5	24 ⅛	5 ⅝	5 19/20
6	24 ⅞	4 ⅞	4 23/24
7	25 4/8	4 2/8	4 ¼
8	26 0/0	3 0/8	3 23/32
9	26 ⅜	3 3/0	3 11/36
10	26 6/3	3 0/0	2 39/40
12	27 ⅛	2 ⅝	2 23/48
14	27 4/8	2 2/8	2 ⅛
16	27 ••/8	2 0/0	1 55/64
18	27 ⅞	1 ⅞	1 47/72
20	28 —	1 6/8	1 9/80
24	28 ⅛	1 4/8	1 22/96
28	28 ⅜	1 ⅜	1 1/16
32	28 4/8	1 2/8	0 110/128

• A, The Number of Equal Spaces at the Top of the Tube, which the same Parcel of Air was contain'd in.
• B, The Height of the Mercury, which together with the In∣cluded Air, counterpois'd the Pressure of the Atmosphere.
• C, The Pressure of the Atmo∣sphere.
• D, The Aggregate of B to C, representing the Pressure counterpois'd by the Included Air.
• E, What that Pressure should be, according to the Hypothesis.

In which Experiment it is to be Noted, First, That we made use of a Glass-Tube, about 6 Foot long, sealed at one End.

Secondly, We had in Readiness a Glass-Pipe, about the Diameter of a Swan's Quill, which was mark'd with a Paper stuck upon it, divided into Inches, and half Quarters; which being im∣mers'd in the other Cylinder of Mercury, and open at both Ends, that the Mercury might rise in it, it help'd to fill the other up. And about

an Inch of it's standing above the Mercury, the Orifice was seal'd up; so that an Inch of Air was contain'd in the Tube, which, by lifting up the Tube, was gradually expanded to several Inches: It being noted, in the mean time, how much the Mercury in the small Tube, was, by the Expanded Air, in several Stations, permitted to rise above the Surface of the Mercury in the other Tube: By which Method, the former Observa∣tions being made, we inverted the Large Tube, and found by trying the Torrecellian Experiment, That that Day the Air sustain'd the Mercury at 29 ¾ Inches; where it was observ'd, That in ma∣king the foregoing Observations, the Difference betwixt the Account which answers our Hypothe∣sis and the other, probably proceeded from a new Access of Air, to that included Inch; and indeed, by immerging the Tube, when the Observations were made, we found, that it had gain'd about half an Eighth; which we judg'd might arise from some Bubbles lodg'd in the Pores of the Mercury. From which Experiment it appear'd, that the Inch of Air expanded to double it's Dimensions, was able with a Cylinder of Mercury abuot 15 Inches, to counterpoise the Pressure of the Atmosphere, which would raise the Mercury eight and twenty Inches, when the Spring of that Air was lost, by a further Expansion: So that the Atmosphere here below, must consequently be as much compress'd, as if twenty eight Inches of Mercury gravitated upon it.

CHAP. XX. Objections against Particular Phaenomena answered.

* 1.129WHAT our Author says in the Vindica∣tion of Particular Experiments, being only a Repetition of what he had said before against the Objector's Funicular Hypothesis, there is no need now to make a Repetition; since the Funicular Hypothesis, being already confuted, it conse∣quently follows, that the Explications are Er∣roneous.

I shall therefore only take Notice of what hath not yet been deliver'd, or not so fully explain'd.

And First, The Reason why the Air condens'd in Winter, by Cold, does not buoy up the Mer∣cury equally, as when the Air is condens'd in a Vessel, is because that condens'd Air adds no greater a Weight to it; but as a pound of Fea∣thers, it is as heavy when compress'd, as before that Compressure; but when expanded Air is condens'd in a Vessel, it acts more Powerfully by Virtue of it's Spring.

Mr. Boyl hath taken a great deal of Pains in his Explications, to shew several Absurdities in the Objections; but those being neither Useful, nor Instructive, especially considering the Objector's Hypothesis is wholly laid aside, and our Author's Receiv'd, it will be needless to take notice of what will be of no Use in Explicating the Phaeno∣mena before deliver'd.

CHAP. XXI. An Explication of Rarefaction.

IT being objected by the Author of a Book, De Corporum Inseparabilitate, that the Spring of the Air cannot be made out, whether we allow a Vacuum, or a Plenum. Waving the Forms which he lays his Objections down in, and a particular Answer to his Ways of Arguing, I shall take the following Method, to explain the Air's Spring. For supposing the Particles of the Air to consist of Matter, extended into thin Laminae, and those wound and folded up, like the Spring of a Watch; and that these Parts of Matter so wound up, are in a Continual Circular Motion, it will follow, that the Laminae in this Motion will en∣deavour to extend themselves, and to recede from the Axis or Center of their Motion, till hinder'd by the Opposition of each other, or some adja∣cent Bodies: and this Expansive Endeavour will be proportionably increas'd, as the Circular Mo∣tion of those Particles is quicken'd. And these Springy Corpuscles thus shap'd, and thus Me∣chanically mov'd, are sufficient to account for all that we ascribe to the Spring of the Air. For supposing the Diameter of those Parts of Matter next the Surface of the Earth, compress'd by the whole Weight of the Incumbent Atmosphere, to be 1/1000000000000 of an Inch,* 1.130 and to be represented by the Third Figure A B C D; it will Naturally follow, that Part of the Incumbent Weight of the Atmosphere, being taken off, they will expand

themselves so as to be 10/1000000000000 of an Inch in Diameter, as represented by E F G H. so that these Zones whirling round, will take up a space 1000 times bigger than before. And as from hence the Rarefaction of the Air is naturally accounted for; so the swelling of a Carp's Bladder, upon taking off the Pressure of the Atmosphere, is explain'd by the same Reason. And as the spon∣taneous Rarefaction of the Air is hence naturally explain'd, so it's Forced Rarefaction by Heat, is; for if the Particles of Heat penetrating the In∣terstices of these Aery Particles be in a violent rapid Motion, by increasing the Motion of the former Particles, they increase the Motion of the latter, and consequently strengthen their expan∣sive Virtue; And if these Rarifi'd Parts of Mat∣ter, by expanding themselves, leave larger In∣terstices betwixt their Laminae, they must conse∣quently be more pervious to the Rays of Light. So that granting this innate Motion in the Parts of Matter, and such a Configuration as I have mention'd, it naturally follows, that all the Phae∣nomena belonging to Rarefaction and Conden∣sation, may easily be explain'd by it.

* 1.131Nor will it be impossible to explain the Rare∣faction and Condensation, admitting of a Ple∣num, if we suppose with Cartesius, That the Air consists of Parts which are long, slender and flexible; for supposing with him, that these are whirl'd round by the Rapid Motion of the Glo∣buli Coelestes, those that lie next the Surface of the Earth, must needs be compress'd and hin∣der'd from that expansive Motion, more than those that have less Weight upon them; and consequently, when that Compression is taken

off, the expansive Force being encreas'd by it, they will consequently be expanded more Pow∣fully; and by whirling round, acquire longer Vortices: And for the like Reason the Air con∣tain'd in the Carp's Bladder, will extend it self when the Pressure of the External Atmosphere is taken off; and consequently, when the Exter∣nal Pressure is again admitted, those springy Parts being again compress'd are less able to maintain their new Vortices, but being wound up together again become more condens'd, that Pressure resisting the Force of their Spring. And as for the Reason why Water flows into the Re∣ceiver again in the Magdeburg Experiment, so impetuously; it hence evidently appears to pro∣ceed, from the Weakness of the Spring of the included Air, not being able to resist the more violent Pressure of the External; and for the same Reason likewise, the Carp's Bladder upon a reingress of that Air, is presently compress'd into its former Inconspicuousness.

* 1.132Nor will it be a less Piece of difficulty to ex∣plain the Aptness of Explosion in Gunpowder, by the Cartesian Hypothesis; for the Parts of that Combustible Matter of which it is made being shattered and broke into Pieces, consequently become more apt to be whirld about by the Materia Subtilis, and justling against each other, take up 1000 times as much space as before; and these Parts being thus agitated whatever Gun∣powder they fall upon, they presently shatter its Parts so as to put it in a Capacity to be agi∣tated by the Materia Subtilis: and consequently, the Globuli secundi Elementi, being expell'd out of the Place which contain'd the Gunpowder,

and the Parts of it being impetuously mov'd in that, they not only burst the Vessel they are con∣tain'd in, but drive every thing out of its Place which stands in their way, and is not able to re∣sist them.

CHAP. XXII. An Explication of the Rota Aristotelica.

NOT to mention all those Absurdities which Mr. Boyle hath shew'd in the Author's Explanation of the Rota Aristotelica,* 1.133 I shall pass on to lay down what Explanation Mr. Boyle himself gives of it; for Mr. Boyle conceiving no such Difficulties in it, as our Author would represent, says, that it is so far from containing any Obscurities in it, that it is plain and easie. For if the Wheel A B C D. be mov'd in a di∣rect Motion from A I C. to K L M. each of the Points A E I G C. will either on a Plain, or in the Medium it passes through, form so many parallel Lines to I L. But if instead of that direct Progres∣sive Motion, it have a Circulation, each Point in one Revolution, whilst mov'd from G to L. will form a Cyclorid. Besides, each Point of the Circle acquires various Degrees of Celerity in its Pro∣gression by this complex Motion, according to its various Position to a Point, which is always to be found in some part of the Line, drawn from the Center of the circular Motion Perpendicu∣lar to the Progressive; for as the Circumfe∣rence to the Radius, so is the Line of the Pro∣gressive

Motion to the distance of the Point from the Center; because the Line of Progression is equal to the Circle, describ'd on that distance as Radius; and therefore, each Point of the smal∣ler Circle, when it touches the Perpendicular, will in respect of its Progressive Motion stand still: This Point therefore, will be the Center of the complex Motion.

* 1.134But since it may sufficiently explain the Rota Aristotelica, if we only consider those Points which pass across the Perpendicular, we shall suppose in our Example that A is the Center or immoveable Point; and then the Circumference A B C D will be equal to I L or A K by our Hy∣pothesis. And since the Point I hath only one motion, viz. that of Lation, the Point C which hath two Motions, must have double the Velo∣city of I, and the Point F having the same De∣gree of Lation with I, and put half the Distance of C from the Center I, it must have one Degree of Motion and a half.

And further, the Point E having the same Progressive Motion with I, and being mov'd backwards with half the Velocity, loses half the Progressive Motion forwards. And the Point A being by its Progression mov'd forwards, with an equal Velocity with I, and by its Rotation (the Circle A B C D being equal to the Line I L) being carri'd back with equal Celerity, must ne∣cessarily stand still as to the Progressive Mo∣tion.

Now from hence it appearing, that the Point A, (being at Rest, by reason of its two oppo∣site Motions) only touch a Point of the Line A K, without being in the least mov'd upon it,

and that the Point E, (moving forwards as fast again as it is carri'd backwards by its Rotation, and consequently mov'd half as fast as the Point I) not only touches the Line E K, but is mov'd upon it with a progressive Motion, half as quick as that of I, it will consequently follow, that each Point in E must make a small Line, which is a Part of the whole E C; so that the Contact of the former, and the Contact and the Progression of the latter, being perform'd by an infinite Suc∣cession of Points, in an infinite Succession of Instants, the Difficulties represented by our Author's Explaining it, are taken off, all that he says coming to no more, than that in such a determinate Moment or minutes Space of time, such a determirate minutes Corpuscle, will successively pass over such a determinate Space or Length.

CHAP. XXIII. An Abstract of what is further contain'd re∣lating to the Weight and Spring of the Air in the Examen of Mr. Hobbs his Dialo∣gus Physicus.

IN this Chapter I shall not take notice of what Absurdities the Author hath shew'd Mr. Hobbs guilty of, but shall only extract what may tend to a further Illustration of the Doctrin of the Air's Weight and Spring.

And first, from what hath been before deli∣ver'd concerning the Weight and Spring of the Air, it appears, that the Reason why the Wa∣ter

in a watering Pot, is prevented from descen∣ding through the Holes of the Bottom, by stop∣ping the upper Orifice, is no other than the Pressure of the Atmosphere; which making a stronger Resistence than a Cylinder of Water of such a Length is able to resist, it must conse∣quently be suspended in the watering Pot: and that this is the true Reason, appears from what hath been deliver'd in the nineteenth Experi∣ment; where it was made evident, that if the Pressure of the Air was weaken'd by extracting the Air out of the Receiver, as soon as the Water in the Tube was able to out-balance the Spring of the included Air, it began to subside.

CHAP XXIV. The VVeight and Spring of the Air asserted.

THE Author having prov'd the Weight of the Air, by weighing it in an exhausted Re∣ceiver in a Lamb's Bladder, and a Glass Bubble, and likewise in an AEolipile: And the Air's gra∣vity being further confirm'd, by weighing the Receiver before and after it had been exhau∣sted in the Magdeburg Experiments: All that Mr. Hobbs objects, relating to the Bladder weigh'd in the Receiver, only intimates, that the Air being blown into the Bladder, the Weight proceeds from Atoms which swim in that Air, or the Haltius which pass into the Cavity of the Bladder along with the Air: But since this de∣nies

not the Weight of the Air, but rather que∣stions the Cause; we think it sufficient to ac∣count for what we aim'd at, to prove, that Air does gravitate, tho' the Cause of Gravitations be not known.

* 1.135As to the Spring of the Air, waving what trivial Objections Mr. Hobbs makes, I shall add the following Experiments to evince it.

The first, is, That if a Cylinder of Mercury be suspended at the usual Height, in the Torre∣cellian Experiment, by stopping the upper Ori∣fice of the Tube, and lifting the lower End above the Basis it rested on before; we may observe, that the Finger can discern no Gravitation of the Mercury in the Tube; but if it be inverted, and the External Air let in, the Mercury which be∣fore did not gravitate upon the Finger, will be so depress'd by the Spring of that Air, as to cause it to weigh considerably upon it; and if the lower Orifice be unstopp'd in the restagnant Mercury, the included Air will depress that in the Tube, below its former Stations: And if the Experiment be made in a Tube not so long, and both Ends be stopp'd with ones Finger, up∣on the removing of the uppermost, the lower will perceive the Weight of the Incumbent Pil∣lar of the Atmosphere, which before depress'd the Pulp of the Finger into the Cylindrical Ca∣vity of the Tube; so that this Experiment proves both the Spring and Gravity of the Air.

The other Experiment is the Fourth in the E∣pistle, where it was evident, that a Bladder sus∣pended in the Receiver, subsided or swell'd as the Air was let in, or drawn out: And tho' Mr. Hobbs teaches, that the swelling of the

Bladder is effected by the Air, per vim incussus, which getting into the Bladder, presses against the Internal Superficies of it in their circular Motions; yet, since from several Experiments it appears, that Bladders are impervious to Air, to deny that the Ingress of it, is a sufficient An∣swer to his Explanation: But further, were the Bladder so pervious to Air, it might as readily get out of the Bladder, as in, without breaking it.

And whereas Mr. Hobbs endeavours to expli∣cate all the Phaenomena afforded by our Engin and Wind-Guns, by the Motion of the Aery Parts, which Motion they acquire by the Force of the Engin; yet, that the Air hath parallel Effects where it acquires no such Motion, ap∣pears from the Experiments formerly mention'd made in the open Air, at the Top and Bottom of Hills; the Mercury being not near suspended so high at the Top, as at the Bottom of those Hills. And tho' he endeavours to Explain the difference, by supposing the Motion of the Air brisker at the Bottom than the Top of the Hill; yet, since it can only keep the Mercury from subsi∣ding, by virtue of its Pressure, that Pressure must either proceed from its Spring or Weight; and since it is highly improbable, that the Pressure of so few Parts of the Air, as are contiguous to the Mercury, should be able to keep it from sub∣siding, it must do it by virtue of the whole At∣mosphere which is equiponderant to it.

But to evince the Spring and Pressure of the Air further, I shall add, that a Thermoscope be∣ing carri'd to the Top of a Hill, the Air con∣tain'd in it not finding so strong a Pressure from

the Water, which there receives a less Impressi∣on from the Atmosphere, visibly expands it self by virtue of its Spring.

CHAP. XXV. Mr. Hobb's Principal Explications of the Phaenomena of the Engin Examin'd

BEfore Mr. Hobbs sets about an Explication of the Phaenomena exhibited by our Engin, he lays down an Hypothesis, which he endeavours to explain them by; supposing that a great many earthy Particles are interspers'd in the Air, which have a congenite circular Motion of their own; and that there is a greater Quantity of them nearer, than further from the Earth: But be∣sides that it may be question'd, how such Parti∣cles can move in so exact an Order, without knocking against, and disturbing each others Motion: It is as unintelligible how Matter should have its Motion congenite: But to leave Mr. Hobbs to dispute these things with other Ad∣versaries, I shall proceed to his Explica∣tions.

* 1.136And first, to prove that there is no Vacuum in our Receiver, he says, that the Air being remov'd by the Pressure of the Sucker outward, it gets into the Receiver again betwixt the Convex and Concave Surfaces of the Sucker and the Cylinder, which if. true, it would follow, that there was a Vacuum for some time, viz. till the Air had time to get into the Re∣ceiver

again. But that the Air is in a great Measure drawn out, and that the Receiver is, in respect of Air, empty, not only appears by those Bubbles of Water which pass through the Water, when the Receiver is encompass'd with it; but it further appears, by weighing the Re∣ceiver when exhausted, which is considerably lighter than before. As also, by observing, that if the Receiver be ill shap'd, so as not to be able to resist the Pressure of the outward Air, it breaks inward upon the Action of the Pump. But a further Argument is, that the Receiver being exhausted, and the Cocks turn'd when the Receiver is encompass'd with Water, seve∣ral Gallons will be impell'd into it, which could not be without a Penetration of Dimensions, except the Receiver was empty. And even in the Common Experiment its evident, that the Air, upon turning of the Stop-Cock, rushes in with a considerable Noise.

But if Mr. Hobbs should say, that the Purer Air only flows into the Receiver; I shall demand, how it is possible for that to flow in, when the Receiver is exhausted in Water; where we might expect, that it should as well raise Bub∣bles in its Passage through it, as that such Bub∣bles rise in the Water in the exhausted Re∣ceiver.

And tho' Mr. Hobbs affirms, That this Air getting into the Receiver moves up and down violently I know not how; to prove that it does not I shall intimate, That were it so, the Smoak as well as the Bladder contain'd in the Receiver in the forementioned Experiments, would be disturb'd by that Motion; since upon

the Admission of the Air into the Receiver, it appears, That it puts them both into a very violent Agitation.

And, That in the Torrecellian Experiment, the Tube above the Mercury is void of Air, may be evinc'd, by reciprocally inverting the Tube; for by that Means, the Mercury will move back∣wards with a much greater degree of Swiftness and Force, than if Air be let into that Part of the Cylinder which is not filled with Mer∣cury.

And indeed, were it not allowed, That the Air is drawn out of the Receiver, for any thing that Mr. Hobbs hath offer'd, the Reason of the Ascent or Descent of the Mercury, as the external Air is let in or drawn out, would be difficulty understood, if not altogether un∣explain'd, without admitting the Weight and Spring of the Air.

The next Phaenomenon Mr. Hobbs offers to ex∣plain is, why the Sucker rises up when the Re∣ceiver is exhausted, tho' a hundred Pound Weight be suspended at it; the Reason of which he attributes to the swift and violent Reper∣cussion of the Air, which was thrust out, which finding not room enough in the World, must conseuqently press the Sucker before it into the Space which contain'd it before; but if the Air be so swiftly repelled, I cannot understand, why it should not resist the Egress of Air, or raise the Sucker when a greater Weight is hung at it. But further, that the return of this Air does not depend on the swift Repercussion of the external Air is hence manifest; since if the Sucker be held down till the Air about it seems

to be settled, and as calm as before; it will nevertheless rise when the superfluous Weight is taken away. And as for an Internal Conatus of the Included Air, were such allow'd, as Mr. Hobbs contends for, it would rather hinder than promote the Rising of the Sucker; for were that Included Air forc'd out so violently, as he sup∣poses, and were it strong enough to cause a vio∣lent Repercussion in the Air, the Internal Force counterpoizing the External, the Rising of the Sucker would not thereby in the least be pro∣moted: But since from our Experiments it ap∣pears, That the Receiver is, for the greatest Part, void of Air, and that such an Impetus would be of no Force, in causing the Phaenomenon he en∣deavours to explain by it, it is more Natural to belive, that the External Pressure of the Atmo∣sphere rais'd it.

CHAP. XXVI. Several scatter'd Explications, and Passages in his Dialogue, consider'd.

WHEREAS we have in the XXXXV^th Experimenti, mention'd an Experiment, wherein the Water Rose up into a long slen∣der Tube, which was plac'd in a Perpendicu∣lar Line; the Water in the Tube, being above the Surface of the Water, without the Tube; Mr. Hobbs endeavours to explain this, by the Impulse of the Particles of Matter, swiftly agi∣tated in the Air; but since the same Agitation

of Parts within the Tube, might also depress that to an equal Surface, with the External, the Account he gives of it, is the less satisfactory.

The Reason which he assigns for the Difficulty in drawing up the Stopple, when the Receiver is exhausted, is, a Violent Conatus, proceeding from the Motion of the Particles within; but were the Impetus so great, as to cause so great a Repercussion, as Mr. Hobbs before suppos'd able to repel the Sucker, it should rather raise the Stopple; and if that Motion contributed to the fastning of it, it would continue upon a Re∣admission of the Air; since the Air in the Ca∣vity runs about, and is in Motion for a good while: Nor could the Plentitude he supposes, cause the Phaenomenon, because he supposes the World to be equally, and at all times full. But that the close Connexion of the Stopple to the Socket, depended on the Pressure of the Ex∣ternal Air, appear'd by closing the Hole in the Cover with Cement, instead of that Stopple; for when the Air was drawn out of the Receiver, the External Air was drawn out of the Receiver, the External Air would press so violently upon it, as to make the upper Superficies Concave, and sometimes to force it down into the Receiver with a Noise, and great Violence.

He further assigns the Boiling of Water in our Receiver, to the Motion of the Air included; but since I have made it appear, That there is no such Motion, our Explanation is the more pro∣bable; since the Parts of the Liquor being agi∣tated by Heat, will be apt to to expand more powerfully upon a Removal of that Pressure.

And tho' he says the Parts of the Water could not be mov'd, except à Movente contiguo, A Con∣tiguous

Body in Motion; yet since he allows, that the Motion of his Earthy Parts, which swim in the Air is innate, and consequently depends not on any Contiguous Body, I shall leave that to answer what he here delivers; and shall only intimate, That the Parts of the Water being agi∣tated, when put into the Receiver, is enough to account for the Phaenomenon, when the Pressure of the Air is taken off.

* 1.137The sudden Death of Animals, which I ascribe doubtingly, tho' not without Probability, to the Exsuction of the Air in the Receiver, he attri∣butes to the Circular Motion of the included Air, and it's Tenacity; but since I have already made it appear, that there is no such Motion, that is a Sufficient Answer. And as for the Air, being thicker in the Exhausted Receiver, than before, the contrary appears in the Magdeburg Expe∣riment; where the Exhausted Receiver weigh'd much less than before; but from the Breaking of Bubbles outwards it further appears, that it is not a thicker, but a lighter and more yielding Body: And tho' Mr. Hobbs from his supposition of the Air's Thickness, endeavours to Account for the sudden Extinction of Flame in our Re∣ceiver; yet thinking it a Matter of Difficulty to explain, the true Cause of the Extinction of Flame, it may suffice, that I have made it ap∣pear, that the Air is not thick as he supposes.

CHAP. XXVII: Several other Passages in Mr. Hobbs's Dia∣logue, examined.

IN this Chapter Mr. Hobbs objects against what our Author delivers, concerning the Cause of the Coliesion of two Marbles; but all that is contain'd in what he here offers, being obviated by what hath been deliver'd under the Title of Fluidity, and Firmness; For a further Confirmation of the Doctrin there deliver'd, I shall add the following Experiments: And,

* 1.138First, If an Aeolipile freed from Air, be, whilst hot, stopp'd with Wax, upon a Perforation of that Wax, the Air will be press'd in to the Cool Aeolipile, whether the Orifice be held down, or Horizontally; which shews, that the Air on each side may press upon the Lower Superficies of the Marble, as well as the Subjacent Pillar of Air, and that the Air is not impell'd against it only in a Pyramidal Figure, as he would urge, viz. be∣cause Lines drawn from the Circumference and Borders of the Stones, to the Center of the Earth, must form Pyramids.

To which it might be added, That Part of the Air being drawn out of a large Glass, and a Book clapp'd upon the Orifice, the Pressure of the Sub∣jacent Atmosphere, kept it suspended there.

And the Author of the Magdeburg Experiment says, That two Plates of Copper, whose Diame∣ter was about half an Ell, stuck so close to each other, that six Men could not pull them asund.

* 1.139And it appears from an Experiment made in a Glass Viol, anon to be describ'd, that if the Tube be so immers'd, that it's Lower Orifice just touch the Water, the oblique Pressure of the Atmosphere, will raise the Water in the Tube, a considerable Height, as the Air is suck'd out of the Tube.

Mr. Hobbs objects against the Author's Expli∣cations of the Rising of: Water in Glass Foun∣tains; and says, That it cannot be accounted for by the Expansion of the Air, since the Parts of the Air expanded, take up no more room after they are expanded, than before; but since he means so as adequately to fill more Space; and we only mean such an Expansion, as is before ex∣plan'd, by instancing compress'd Wool; it ap∣pears, that in our Sense it will take up more Space, so as to keep the gross Parts of Water from getting betwixt them.

There are other Objections mention'd in this Chapter, as well as some other Particulars, rela∣ting to the Royal Society; but since the Author finds no weight in them against any thing he hath taught; I shall only further take Notice of what Mr. Hobbs and Gassendus teach, concerning the Rise of Water in Syphons; viz. That it is perform∣ed by Suction. But not now to mention what hath elsewhere been deliver'd to prove the contrary, I shall only add the following Experiment: Ha∣ving taken a Glass Vessel, which was large enough to contain about a Pound of Water, I caus'd a Glass Pipe to be fix'd in the Neck of it; so that the Air within was kept from having any Inter∣course with that without, the Lower End reach∣ing almost to the Bottom of the Vessel: The Pipe being thus fix'd, we convey'd Water into the Bot∣tle,

till it rose something above the Bottom of the Pipe, and then having inclin'd the Bottle to give a due Intercourse betwixt the Internal and Ex∣ternal Air, I suck'd the Air out of the Tube, till the Water rose into my Mouth, and till the Spring of the Included Air, was able no longer to lift up the Water; which would not have done, been were the Common Notion of Suction allow'd, viz. That it is effected by the Pressure of the Air, thrust away by the dilated Chest of him that sucks, and thereby drawing the Water into the Pipe at which he sucks.

But besides the Preceding use made of this Ex∣periment, I pour'd out the Water, till the lower End of the Pipe was but just immers'd in it; and upon Suction, it rose almost to the Top of the Pipe; but the Spring of the Air being too much weaken'd to raise it higher, several Bubbles of Air broke through the Water; but as soon as I left off sucking, the Pressure of the External Air so compress'd the Rarify'd Air within, as to bring it to it's wonted Station, several Particles breaking into the Bottle through the Water, till that Internal Air was equally press'd with the External.

CHAP. XXVIII. What Mr. Hobbs teaches concerning Fluidity and Firmness, examin'd.

* 1.140THE First Particular examin'd in this Chap∣ter, is a Mistake of Mr. Hobbs, concern∣ing the Author's Opinion of Fluidity; the Ob∣jector making the Author's Notion of Fluidity to consist in the Size of the Parts of Liquid Bodies; whereas our Author assigns Motion, as the Chief and Principal Qualification; since a Coagulum of pure Spirits of Urine and Wine, may by bare Digestion, be turn'd into a Per∣manent Liquor; and Quick-silver, tho' fluid, may be turn'd into a Permanent Powder, by stopping the Motion of it's Parts. And tho' Mr. Hobbs further asserts, That Fluid Bodies con∣sist of Parts Divisible into Fluids, as Quantity into Quantity; yet, since I have made it appear, That Fluidity depends on the Shape, Size, Tex∣ture, and Motion; and Firmness, on a Rest amongst the Parts of Solids; and likewise, that Fluids are not divisible into Fluid Parts, as Quan∣tity into Quantity, it is needless to repeat what is there deliver'd.

As for the Explication of Fluidity and Firm∣ness, which Mr. Hobbs Substitutes, it teaches, That the Parts of Fluids may move whilst the whole is in Motion, and that Solids may have their Parts in Motion, tho' the whole lyes still: As also he says, That the Parts of a Fluid may be render'd less fluid, by being compress'd; but since he hath

asserted these things, and not prov'd them; and since the Hypothesis he goes upon, is sufficiently invalidated before, the Author thinks these re∣quire no Particular Answer: And tho' he fur∣ther makes an Objection against the Size of the Parts of Matter contributing to Fluidity and Firm∣ness; yet since our Author makes Motion or Rest the Chief and Principal Requisites, what hath been deliver'd in the History of Fluidity and Firm∣ness, may suffice for an Answer: For that there is Motion in the Parts of Fluids, appears, if a Lump of Salt be put into Water, the Parts of which will be presently dissolv'd, and carry'd up to the Top of the Liquor, which could not be without Mo∣tion; and that Rest contributes to Solidity, is evident, since Water froze, becomes Ice; and on the contrary, that, as well as Metals, by having their Parts put into a violent Motion by Heat, become Fluid.

CHAP. XXIX. An Explanation of the Engin made Use of in the following Experiments.

* 1.141THE Structure of our Engin being such, as not to admit of an Alphabetical Explana∣tion, so as to make it intelligible, to those that are unacquainted with Mechanical Structures; and it being easily enough understood by those, espe∣cially that are acquainted by our First Engin, we

thought it sufficient in our Plate, to repre∣sent the Engin just ready to be set on Work; and in the Fourth the Parts, which it is made up of. Only there are two things, which may deserve to be explain'd: First the Sucker being always co∣ver'd with Water; and the Perforation (p q), which goes through it in a Perpendicular Line, and together with the Stick (r s), supplies the Place of a Valve, being to be stopp'd at the Bot∣tom of the Cylinder (n o), when fill'd with Wa∣ter, it was necessary the Stick (rp) should be of a considerable Length. Secondly, The Pipe (A B) lies in a Gutter, made purposely in the Board (c d e f), which Board is laid over with Cement, and a piece of Iron laid upon that, to keep it from warping: In which Iron-plate is fix'd a Lip, which rises up about the End of the Pipe (B), which is bent up, to prevent the Water which comes from the Receiver from be∣ing Spilt; and notwithstanding the Stop-cock (G H I K), might be inserted into the Cylinder (L M N O), at (I) with Soder; yet it is much more convenient to have the Branch (I) made like a Screw; so that being screwed into the Barrel, it may more easily be mended, when any thing is amiss; Whether it be that the Air gets in betwixt the Plate and the Wood, or the Cement be drawn into the Pipe, where the in∣verted End is united to the Receiver; and lest the inward Orifice of the Pipe should be stopp'd with any thing, contain'd in the Receiver drawn to it, there is fix'd at some Distance from it a Tin Plate, so contriv'd as to give free Passage to the Air.

The Wooden Part represented in the Plate, and which contains the Cylinder, is always so full of Water as able to overtop the Cylinder, and to make the Sucker soft and plump, by which means it is more exactly fitted to the Cylindrical Cavity.

And as for the Iron Plate abovemention'd, it hath this Conveniency, that it excludes the Air, better than if the Receiver had a Stop-cock, in most Experiments, tho' in some it is less ser∣virceable.

But most of the following Experiments may be try'd in our First Engin, if the following Alte∣rations be made. And First, If a square Board, and a suitable Iron Plate, such as is made use of in this Engin, be fasten'd opposite to the Iron Rack, to the Upper Part of the great Cylinder, and a Glass Tube, like that just now describ'd, be fix'd to the Lower Branch of the Stop-cock, with a Cement, made with near an equal Propor∣tion of Wax and Turpentine, in Winter, and three Parts of Wax to two of Turpentine in Summer; for the Ingress of Air being thus pre∣vented, upon drawing down the Sucker, the Air, by Virtue of it's own Spring, will force it self out of the Receiver.

CHAP. XXX. A Continuation of New Experiments concern∣ing the Spring and Weight of the Air and their Effects, by way of Letter to the Right Honourable the Lord Clifford and Dungarvan.

My Dear Lord,

HAving already given your Lordship an Ac∣count of the Design and Scope of our Mechanical Experiments, without any further Preface, being encourag'd by your Acceptance of my last, I shall proceed to a Continuati∣on.

EXPERIMENT I. Concerning the Raising of Mercury a great Height in an open Tube, by the Spring of a small Quan∣tity of included Air.

IN order to make an Estimate of the Force of the Air's Spring, in it's several Degrees of Expansion; We fill'd the fourth part of a Viol with Quicksilver, the Neck of which was none of the largest, in which we fix'd a Glass Tube with hard Wax, the lower End reaching almost to the Bottom of the Quicksilver, and the up∣per almost a Yard above the Viol, which being conveigh'd into a Receiver (See Plate 5. Fif. 1.) which was pretty Tall,* 1.142 upon an Exsuction of the Air in the Receiver, that in the Viol ex∣panding

it self, rais'd the Mercury 27 Inches in the Tube; yet when the Air was again admitted into the Receiver, it subsided so far as to be al∣most; if not quite equal with the Surface of the Mercury in the Viol: And this Experiment was try'd before the Famous Savilian Geometer Dr. Wallis, tho' it does not constantly succeed alike, it sometimes rising higher than at others.

In which Experiment the following Observa∣tions were to be made. First, That so much Air being blown into the Viol, to try whether it was stanch, as was able to raise the Mercury three Inches in the Pipe, upon the Exsuction of the External Air in the Receiver, the Mercury rose 30 Inches above that in the Viol.

Secondly, When the Mercury is taken out of the Receiver, it does not suddenly subside as low as before it's Ascent, the Air being a little more Expanded by the Heat of the Cement when melted with an Iron.

Thirdly, Whilst the Air included in the Viol retains any considerable Springiness, after each Exsuction the Mercury will be rais'd by the Force of its Expansion, a considerable Height above what that Air is able to suspend it at, and makes several Vibrations before it settles.

Fourthly, Upon the first Exsuction the Mercu∣ry rises near ⅔ of the whole Weight that the Expansion of the included Air is able to raise it, and continues every subsequent Exsuction to rise less and less as the weight of the suspended Mer∣cury encreases, and the Spring of the Internal Air grows weaker, and as the Mercury rises less every Exsuction than it did before, so are the Vibrations less considerable.

Lastly, Having observ'd the Weight of the Air in a good Barometer, when it was but light, the Mercury was rais'd to 29 and ⅜ tho' soon af∣ter the Tryal it was but 29 Inches high.

To make an Estimate of the Quantity of Air which rais'd the Mercury to the usual height, we counterpois'd the Viol, and then filling it full of Water, we found it to weigh about 5 Ounces 2 Drachms, and about 20 Grains; but so much being pour'd off, that the remaining Water on∣ly filled the Space which the Mercury was before contain'd in, it weigh'd 1 Ounce 2 Drachms 14 Grains, so that the Air which by it's Expansion elevated the Mercury, fill'd the Space of no more than 4 Ounces and a few Grains: The Diameter of the Pipe employ'd in this Experiment was no more than the ⅛ of an Inch.

* 1.143But besides the Spring of the Air, from this Experiment we may learn, what is to be thought of what some Learned Men teach concerning the Suspension of Quicksilver by a Funiculus, and, it's rising to avoid a Vacuum; for were the first true, it might be demanded, why that Funicu∣lus raises it not above 27 Inches; and as for the latter it's objected, that the Mercury being unable adequately to fill up more Space by rising, than if it rose not, the Reason must be invalid.

EXPERIMENT II. A good Quantity of Air raised the Mercury in an open Tube, no higher than the Weight of the At∣mosphere does in a Baroscope.

HAving put a sufficient Quantity of Mercury into a large Bottle, capable of containing about ssij, we immers'd the one End of a long slender Tube, below the Surface of the Mercu∣ry; and having clos'd the Neck of the Viol with Cement, it was conveigh'd into a Receiver diffe∣rent from the former in nothing but Size; where we observ'd, that the Quantity of Air being greater in this Viol, than that made use of in the former Experiment, it was capable of ex∣panding further, and of raising the Mercury to about 29 Inches and about ⅞ out of which half an Inch being deducted, for the height it was eleva∣ted to by Air injected to try the Stanchness of the Bottle, the Spring of the Air included in the Bottle, rais'd it to 29 Inches and about ⅜; The Weight of the Air in a Baroscope at the same time, elevating the Mercury 29 Inches and ½, which was ⅛ higher than the elevated Mercury in the Receiver. But having continu'd to ply the Pump still longer, we learn'd, that the Spring of the included Air was incapable of raising it higher, than the Weight of the Atmosphere did in the Baroscope.

This Experiment was several times repeated with the like Success, but once, the Pump being ply'd more than usually, the Air contain'd in a Green Glass expanded so violently, that tho' it

could not raise the Mercury higher, it broke the Glass with such violence, that the Piece which flew off crack'd the Receiver.

EXPERIMENT III. The Spring of the included Air, will elevate Mer∣cury almost to an equal Height in Tubes of a diffe∣rent Bore.

IN order to try, whether the same Quantity of Air would by it's Expansion raise the Mercury to the same Height in a narrow, as in a Cylinder of a larger Diameter, we repeated the former Tryal with a Pipe of the same Diameter, but much longer; in which the Spring of the Air rais'd the Mercury to 28 Inches and ⅛, the Mercury in the Borometer, being 29 Inches and ¼ high at the same time. So that the Air was able by its Spring, to raise the Quicksilver with∣in an Inch as high in a large Tube, as in a smal∣ler: And when the Spring of that Air was no further able to expand it self, the Parts of it be∣ing put into Motion by Heat, the Spring of it was so much increas'd, as to raise the Mercury ⅝ of an Inch higher.

EXPERIMENT IV. A new Hydraulo-Pneumatical Fountain made by the Spring of uncompress'd Air.

HAVING put a Quantity of Water into a Bottle, and immers'd the End of a Glass Tube a little below the Surface of it, which was

about 3 Foot long, the Interstices betwixt the Neck of the Bottle and the Pipe were fill'd with Cement (see Plate 6. Fig. 2.) and the whole was conveigh'd into a Receiver.* 1.144 And because the Pipe was too long to be contain'd in the Re∣ceiver, another made of White Glass was Ce∣mented upon the former, to the middle of whose Cavity, the upper End of the Pipe extended, so that the Motions of the rising Water had more Space to move in, when the Pump was set on work; where it was observable, that upon the first Exsuction the Pressure of the external Air being taken off, that contain'd in the Bottle, expanded it self so powerfully, as to raise the Water in the Tube with such Force, that it flew violently against the Top of the Receiver; but as the Air in the Bottle was leasurely expanded, and came nearer to an Aequilibrium with that in the Receiver, the Spring of that in the Bottle, being less powerful, the Water in the Tube gradually ceas'd in its Ascent, unless the Pres∣sure of the external Air was taken off by a fresh Exsuction

In which Experiment, the following Particu∣lars were to be noted; First, that as the upper Orifice of the Tube was narrower, the Water would rise slower, and the Experiment would be longer continu'd. Secondly, If a Pipe be Cemented upon the Top of the Tube, and branch'd out into several small ones, with Pin∣holes in the Ends of them, the Water will fly out, as out of Artificial Fountains in Grotto's. Thirdly, If the Bottle to whose Neck the Tube was Ce∣mented, was larger, the Water would rise so much the longer; and the Experiment might

be reiterated by first letting in the Air again, and then exhausting the Receiver by pumping it out afresh.

From the Phaenomena exhibited by this Expe∣ment, it appears, that the Spring of the Air was able to raise the Water in the Tube to a much greater Height than the Pipe we made use of. Secondly, From hence it appears, that Wa∣ter contain'd betwixt two Parcels of Air, may be put into Motion by its Spring, without the Concurrence of adventitious Heat. Thirdly, we observ'd, That when the Air was in a great Measure exhausted, the upper Receiver being taken off, the external Air press'd the Water quite down to the Bottom of the Tube, and se∣veral Bubbles getting through the Water, joyn∣ed themselves with the Air in the Bottle: But what was more strange was, that when the Re∣ceiver had been taken off a considerable time, several Bubbles of Air continu'd to make their way through the Water, as if the Spring of the Included Air, being before expanded, could not be brought again to its former State of Com∣pression; but like a Balance put in Motion, con∣tinu'd several successive Vibrations, resisting each Impress of the Atmosphere.

But the Chief Remark in this Experiment was, that the Salient Water in the Receiver, form'd several large Lines, some of which were Parabolical, when the Receiver was pretty well exhausted.

EXPERIMENT V. About the Production of Heat by Attr••••tion in the exhausted Receiver.

IT being the Opinion of some Learn'd Men, that the Incalescence of solid Bodies depends on the Attrition, or violent Agitation of the intercepted Air; To try how far this might be true, I caus'd a strong Spring of Iron or Steel (See Plate the Sixth,* 1.145 Fig. 3.) Figur'd much like the Lathe of a Cross-bow, to be fix'd to a staple Trencher: On the upper Part of the Spring was fix'd a Concave Piece of Brass, like a Burning-Glass, about 2 Inches Diameter, and moderate∣ly slender; to the Concave Superficies of which, was fix'd a Convex Piece of the same Metal; which had a square Handle on the upper Part, to which was fix'd a square piece of Wood, the other End being fix'd to the Basis of a Wooden Pillar, made use instead of our Vertical Cylinder; and the upper End of this Pillar was fix'd to the Turn-Key, being of such a Size, that when the Stopple was depress'd into the Socket made in the Brass Cover, the Concave and Convex Su∣perficies of the two Pieces of Brass, contain'd betwixt the Wooden Pillar and the Spring, were squeez'd together, and the Spring in some mea∣sure expanded.

All things being thus provided, and a Mercu∣rial Gange conveigh'd into the Receiver, a Wimble was fix'd to the Top of the Stopple, which being turn'd round for some time, and the Air being exhausted out of the Receiver, we

presently took off the Cover; and perceiv'd, that the contiguous Superficies of the Pieces of Brass, betwixt which we had laid some powder'd Amel to make them move more easily one upon another, were sensibly warm.

And the Experiment being repeated a second time, and the Air so far exhausted, that the Mer∣cury was no further depress'd, they grew so hot, that I could scarce endure to touch them; and a considerable Degree of Warmth succeeded, when the Experiment was try'd with two Pieces of Wood, the one of Oak and the other of Beech.

From which Experiment it appears, that At∣trition of Solids may cause a considerable Warmth, when the Air betwixt their Superfi∣cies is exhausted.

EXPERIMENT VI. About the disjoyning of two Marbles (not other∣wise to be separated without a considerable Weight) upon a Removal of the Pressure of the Air in the Receiver.

HAVING several times suspended two flat Polish'd Marbles, whose contiguous Su∣perficies were moistned with Oyl, to keep the Air from getting in betwixt them, upon a con∣siderable Exsuction of the Air, they would some∣times fall asunder in the Receiver, at the eigh∣teenth Suction, and sometimes at the eighth; tho' a Pound Weight was only suspended at the lower; yet in the open Air, where they were

compress'd by the ambient Atmosphere, they were able to sustain 80 Pound without separa∣ting.

But having provided a Receiver with a Brass Conver (See Plate 6. Fig. 4.) and suspended two Contiguous Marbles in it,* 1.146 with a Weight of a few Ounces at the Bottom of the lowest, the String which suspended them being fix'd to the Bottom of the Brass Stopple in the middle of the Cover by turning the Stopple, and by that means shortning the String, the Marbles were rais'd up in the Receiver, but upon drawing out the Air, they presently fell asunder; yet having so contriv'd the Matter, that the lower should not fall too far, the other was let down to it, and upon the Re-admission of the Air, they were so closely compress'd together again, that they could not be separated as easily as before: Yet if by turning the Stopple, the uppermost was rais'd before the Air was let in, it would leave the lowermost behind it.

EXPERIMENT VII. A way to break Flat Glass speedily, by the Weight of the Atmosphere.

TO make it appear, that the round Figure of a Body enables it to resist a more vio∣lent Pressure from the Atmosphere, than Bodies otherwise shap'd; We made use of a Brass Hoop, about 3 Inches high, and 3 Inches and 2/10 in Dia∣meter, and Cementing a round Piece of Glass upon the one Orifice, the other was joyn'd to the Receiver with Cement; and upon drawing out

the Air, the Atmosphere press'd so strongly up∣on the Glass, as to burst it asunder with a con∣siderable Noise, like that of a Pistol. How far this may contribute to account for the Noise which accompanies the Explosion of Gunpow∣der in Pistols, we leave others to consider.

EXPERIMENT VIII. The breaking of the Glass Plates in the foregoing Experiment may be accounted for without a Fuga Vacui.

THAT the breaking of the Glass Plates did not depend on Nature's Abhorrency of a Vacuum, appears hence; for if instead of the former Brass Hoop, we make use of a Vessel Figur'd like a Conus Truncatus, or a Sugar-Loaf, the Cone being cut off; if the lower Orifice be large, and the upper not above an Inch Diame∣ter, the Glass Plate Cemented to the larger Ori∣fice, will break when the Receiver is exhausted; but if the smaller Orifice be upwards, the Glass Cemented to it will be whole; whereas did Na∣ture's Abhorrency of a Vacuum cause the for∣mer, it would have the same Effect in the lat∣ter: Wherefore I rather think the Reason why the latter did not break as the former, was be∣cause a small Basis of the Atmosphere presses upon it, which it is. abler to resist than a larger Plate of Glass.

EXPERIMENT IX.

* 1.147NOT to mention, of what Advantage it might be, to have a Good Method to break Bladders fill'd with Air, in our exhausted Receiver, by supplying it with Air speedily, and without danger of letting in too much from without; I shall intimate, That if a blown Blad∣der be contain'd in an exhausted Receiver, the In∣ternal Air will be so powerfully expanded, as to distend the Bladder, and stretch it's Fibers, which when taken out again, and the Bladder at the Neck, being ty'd something nearer than before, the Bladder so distended with Air, and not liable to give way a second time to the Spring of the Included Air, the next time it is put into the Re∣ceiver, it is apt to burst.

EXPERIMENT X. A Considerable Weight rais'd by the Spring of the Air included in a Bladder.

TO shew that the Force of the Air's Expan∣sion is so great, that ¼ of a Bladder, being fill'd with it, is able to distend it so powerfully, as to swell it up, tho' a considerable Weight be ty'd to the Bottom of it, to keep it from Rising; we fill'd the fourth Part of a Bladder with Air, and tying the Upper Part of it to the Stopple, it was suspended in our Receiver, with a Weight suspended by a String, which was ty'd to the Bottom of it; where we observ'd, That upon the Exsuction of the Air, the Included Air ex∣panded

it self, and distending the Bladder shortned it so, as to raise 15 pound weight.

And another Bladder, having both Ends ty'd to the Stopple, and a Weight suspended at the Middle, of no less than 28 pounds, the expand∣ing Air rais'd that an Inch from the Bottom of the Receiver; but when the Air was again ad∣mitted into the Receiver, it fell down again.

EXPERIMENT XI.

* 1.148HAving clos'd a Glass Bubble Hermetically seal'd, in our Receiver, and pump'd out the Air more than usually in such Experiments, about four Minutes after the Pump ceas'd to work, the Bubble unexpectly flew into so many pieces, and with such force, as to be broke against the sides of the Receiver, into a Powder as small as Sand: But this sort of Glass being capable of stretching a little before it breaks, may be a Reason why the Experiment does not always succeed, the Spring of the Air contain'd in it being weaken'd by that Expansion of the Bubble.

EXPERIMENT XII. Tryals representing the Force of the Spring of Ʋncom∣press'd Air upon Staple Bodies.

The I. TRYAL.

HAving cemented a Glass Plate upon the Brass Hoop, mention'd in the Seventh Ex∣periment, and joyn'd the other Orifice of the Hoop

with Cement to the Pump, upon that, a Large Receiver was fix'd: So that the Hoop supply'd the place of a Receiver, and the Receiver kept the Atmosphere from pressing upon it; yet, upon an Exsuction of the Air out of the Hoop, the Spring of that contain'd in the Receiver, broke the Glass Plate into an hundred pieces.

The II. TRYAL.

AND a Receiver shap'd like a Tumbler, which was capable of containing only a sixth part of what the Large Receiver did, being made use of, the Spring of so small a Quantity of Air, presently shatter'd the Glass Plate in pieces.

The III. TRYAL.

* 1.149BUT a Large square Glass capable of hold∣ing a Pound, being made use of instead of the Hoop and the Glass Plate, upon the Exsu∣ction of the Air, it was broke in pieces, both when the Large Receiver was whelm'd over it; and likewise, when a Receiver not much higher than it self was made use of.

In which Experiments we observ'd, That the Air making a greater Pressure on the Sides of the Bottles, than the Top, first broke them. And it was further observ'd, in the last Experiments, that the Glasses did not fly in pieces, till some time after the last Exsuction.

But lest it should be question'd, Whether the Glasses were broke by the Pressure of the Air in the Receiver, we repeated one of the former

Tryals, with the Brass Hoop, leaving a commu∣nication betwixt the Receiver, and the Cavity of the Hoop, a small Tube, whose Cavity was no wider than the Diameter of a Hair, being lodg'd in Part of the Cement; and upon plying the Pump, we found, that the Air, having a free tho' a small Vent out of the Receiver, did not break the Plate as before.

Yet notwithstanding, if the Air be suck'd out of the Hoop too fast, that in the Receiver, not finding quick Vent, will break the Glass Plate, the Pressure of the Air in the Receiver, being too strong to be ballanc'd, by the Resistance of the Air in the Hoop: And for a like Reason a slender Pipe, blown at the Flame of a Candle, up∣on it's first Removal into the Cold, hath it's sides, if thin, squeez'd nearer together, the Pressure of the Outward Air being greater than the Resi∣stance of the Internal.

EXPERIMENT XIII. Suction is able to raise Mercury no highier in Pipes than the Weight of the Atmosphere impels it.

HAving fitted one End (see Plate 5. Fig. 2.) of a Brass bent Pipe to a Stop-cock,* 1.150 and the other End to the Top of a Cylindrical Glass Pipe, near 50 Inches long, the lower End of it was immers'd in a Glass of stagnant Mer∣cury: And tho' the Pump was set on work, yet was it not able to raise the Mercury above thirty Inches, by frequent and reiterated Suctions. But Water being substituted instead of Mercury, it rose, at the first Exsuction, to the Top of the

Pipe; and when the Stop-cock was open'd, it would run down through the Exhausting Brass Syphon. From whence it appears, that the Rise of Mercury depends not on Suction, or a Fuga va∣cui, whatever some Learned Men teach; but is rais'd by the weight of the Atmosphere; since a Baroscope consulted at the same time, made it ap∣pear, that the Atmosphere was able to suspend it at such a Height.

And as this is an Argument against those that dispute for a Fuga Vacui; so it is against those that hold, that it depends upon the Attraction of a Rarify'd Substance in the Top of the Pipe; for tho' we could rarify the Air further, by con∣tinuing the Action of the Pump; yet the Mer∣cury would not rise one jot higher.

ANNOTATION.

BUT the Syphon, here mention'd, being else∣where made use of, it may be requisite to Observe: First, The Pipe which bends so much, is made of Metal, to make it less subject to break: Secondly, The End of it, which is joyn'd to the Stop-cock, must be a little wider than any other Part, to admit the Shank of the Stop-cock: Thirdly, The Cement which joyns the Brass Pipe and the Stop-cock, being apt to be loose; I rather make choice of one, to which a Stop-cock is fix'd, together with a Glass Syphon, about 10 Inches high, (see Plate 5. Fig. 2. where the whole is represented). And tho' this Additional Glass makes the Experiment longer, and more te∣dious, yet it is more useful and secure.

EXPERIMENT XIV. The different Heights to which the Liquors may be elevated by Suction, accordingly as their Specifick Gravity varies.

* 1.151FROM Experiments already laid down, it ap∣pearing to what Height Mercury may be rais'd in a Tube; we may guess at what Height Water might be suspended, by considering that it is 14 times lighter than the former. But to be further satisfy'd, I caus'd a small Pipe, which branched it self into two (see Plate the 5^th Fig. the 3^d) So that a Cylinder being fix'd to each Branch, the Liquors contain'd in the Vessels, in which the lower End of the Pipe was immers'd, would rise proportionably as their Specifick Gra∣vity enabl'd them to resist the Pressure of the At∣mosphere; which being done, and the Pump set on work, Water rose in one of the Cylinders to 42 Inches, and the Mercury in the other Tube not above 3 Inches; so that the Water was fourteen times higher than the Mercury. And to make the Experiment more satisfactory, we let Air into the Receiver, till the Water subsided to fourteen Inches, and at the same time the Mercury was sunk to about an Inch; for in this Experiment it was observ'd, That the Proportion was not so exact as 1 to 14 precisely Specifies, but there∣abouts.

From this Experiment, we may draw Argu∣ments, not only against what is taught con∣cerning Nature's Abhorrency of a Vacuum; but it may likewise more nicely inform us of the

Specifick Gravity of Liquors: For having put into one of the Vessels, under the Glass Tubes, Fresh Water, and into the other Salt Water; when the Fresh Water rose to 42 Inches, the Salt Wa∣ter was but 40 Inches high. But having made use of a Brine, made of Sea-salt, melted in the Air, instead of Salt Water, when the Fresh Wa∣ter was rais'd to 42 Inches, the Brine did not exceed seven. I likewise put into one of the Vessels, when this Experiment was over, a Solu∣tion of Pot-ashes, and Common Water into the other, and when the Water rose to 42 Inches, the Solution was rais'd but to 30.

EXPERIMENT XV. To what Heights Water and Mercury may be rais'd proportionably to their Specifick Gravities.

HAving put Mercury into a Bottle, and pour'd Water into the Bottle upon the Mercury, we immers'd one Pipe so low, as to have it's End in the Mercury; and another Pipe was likewise immers'd in the Water only; which being fix'd by the help of a Cement in the Neck of the Bottle, the whole was convey'd into the Engin, and the Pipes being each divided into Inches, by hard Wax, with which they were mark'd, we observ'd, that the Water rose 15 times as high as the Quick-silver.

EXPERIMENT XVI.

* 1.152HAving put Mercury into a short Tube, and Water into one that was longer; both of them being Hermetically seal'd at one End, we inverted them both, the End of each resting in a Distinct Vessel; which being convey'd into the Receiver, the Water in the Cylinder did not in the least subside, till by Pumping out the Air, the Mercury subsided within 3 Inches of the Bot∣tom, which was sooner than it ought, according to Statical Rules, which we conceiv'd to pro∣ceed from some Aiery Parts, lodg'd in the Pores of the Water, which rising to the Top of the Cy∣linder depress'd it by their Spring; yet the Wa∣ter, when the Mercury subsided to the Height of an Inch, was near as high as before.

EXPERIMENT XVII.

* 1.153TO try how high Water might be rais'd by Suction in a Pump, I provided a long Tube, about thirty Foot long, being made of several Tin Pipes, closely joyn'd together with Soder, and cover'd over with a Black Cement; which, to keep it from sticking to our Hands, we cover'd with Plaster of Paris: To the upper End of this Pipe, was fix'd a Glass Tube, about three Foot long; and to the Top of that was fix'd another Pipe, consisting of two pieces, which made a right Angle with each other, part of which was Parallel to the Horizon,* 1.154 and the other Perpen∣dicular; the lower End being fix'd to the Engin, which was plac'd upon a Flat-roofed House: And

a Vessel fill'd with Water, being put under the End of the Pipe below, the Pump was set on work; and the Water, after a few Exsuctions, was rais'd to the middle of the Glass Tube, emit∣ting several Bubbles, which proceeded from the Air, formerly lodg'd in the Pores of the Water.

But the chief Aim of our Experiment, being only to try to what Height the Water could be rais'd, I caus'd the Pump to be nimbly ply'd, till the Water could rise no higher; which be∣ing done, and the Height of the Water measur'd by a String, we found it to be 33 Foot, and about six Inches; Quick-silver in a Baroscope, at the same time, standing at 29 Inches, and about 3 eights of an Inch; so that the Water was near fourteen times as high as the Mercury.

In which Experiment, that the upper part of the Tube was sufficiently exhausted, appear'd from several Circumstances; as First, If any Air got in at Crannies in the Pipe, it would rise in Bubbles, easily to be distinguish'd, from those which rose from the Pores of the Water; and tho' the Quantity of those Bubbles was considerable, yet more Air being thrown out by the Pump, than could get in, it must needs be empty enough. But,

In this Experiment, it was to be noted, That when first the Water appear'd in the Glass Tube, they would be very numerous, and form a Froth; yet, when the Pumping was further continu'd, they grew less and less: Secondly, we observ'd, that the Water made several Vibrations in it's Rise; which, tho' near a Foot at the first, grew less and less. Thirdly, it may be observ'd, that the Baroscope, consulted before, some time after,

was noted to have risen considerably; so that had the Experiment been repeated again, the Water would have been buoy'd up a good deal higher.

Now from this Experiment it appears, how im∣probable it is, what some Men teach concerning the Rise of Water, in Spiral Pipes, up to the Top of high Mountains; since it is evident, that it cannot be drawn higher than 36 Foot, by a Sucking Pump:

EXPERIMENT XVIII. About the Bending of a Springy Body, in the Ex∣hausted Receiver.

TO be satisfy'd how much the Elasticity of Bodies depends on the Influence of the Air, I fix'd one End of a Whale-bone in a Trencher, and ty'd a Weight to the other, by which it was bent, so low, as almost to touch the Plane under it. This being convey'd into our Receiver, upon the Exhausting of the Recei∣ver, I could not perceive any Alteration.

EXPERIMENT XIX. Concerning the making of Mercurial Gauges, where∣by to estimate how much the Receiver is ex∣hausted.

SEveral Gauges have been made use of to dis∣cover, when the Receiver is well exhaust∣ed, as by suspending a Bladder, which is al∣most empty of Air, or by inverting a small

Tube in which Spirit of Wine was contain'd; but the former taking up too much Room in the Receiver, and the latter not discovering whether the Receiver was exhausted, or not, till the Air contain'd was too much Rarefi'd, for any Considerable Observations; Therefore, to enable me to make more Observations in the seve∣ral Degrees of the Receiver's Exsuction, I took a slender Pipe of Glass, about 10 Inches long, and as small as a Goose Quill, and having melted it at a flame, so as to soften it, and make it apt to be bent; I caus'd it to be put into the Form represented by (Plate 5. Fig. 4.) so that about an Inch of the lower Leg being fill'd with Air,* 1.155 and the rest of that, as well as the greatest Part of the short one, being fill'd with Quicksilver, the Ex∣pansion of that Air might easily be perceiv'd, by pasting a Piece of Paper upon that Tube, divided into several exact Parts; for as the Re∣ceiver is more or less expanded, the Air in the longer Leg of the Gage, will be extended to some of those Marks; and if when the Air is so expanded, the Experimenter desires to know, at each of those Marks, how much the Receiver is exhausted, it will appear by letting in as much Water as the Capacity of the Receiver is able at that time to hold; so that if when the Air is at any determinate Mark, the Water be let in, and it appears, that the Air in the Receiver was so far Evacuated, by observing how much Water will be admitted, when the Air is expan∣ded to each Mark; the Gage, for the future, will not only inform us, how much the Air is exhausted; but by the help of the small Gage, a larger may be made, by putting both into an

exhausted Receiver at once, for by observing, when the Air is expanded to each Mark in the little one, how far it is expanded in the large one; we may learn, how much the Receiver is exhausted, for the future, by taking notice of the Expansion of the Air in the Leg of that lar∣ger Gage. And,

This Gage is much more useful than some o∣thers: First, because the Mercury being a heavy Body, the Air, by expanding it self, is less apt to make it run over, or to make it's way in the Form of Bubbles through the Mercurial Cy∣linder, as it would if other Fluids were made use of instead of it. Secondly, The longer Leg of the Gage is to be mark'd, by sticking Wax or Knobs of Glass to the Pipe, every Tenth being of a different Colour from the rest, at equal Distances from each other, which Divisions will be less subject to be rubb'd off than Papers, which are also subject, in some Experiments, to be wet. Thirdly, The Leg of the Syphon in which the Air is included, may be either seal'd up, be∣fore it is divided by the aforemention'd Marks, or after, by drawing out the End of the Tube into a small Apex; and when about an Inch of the Pipe is fill'd with Air, it may be seal'd up by blowing a Lamp Horizontally upon the Apex. Fourthly, Where very Nice Observations are to be made, and the Receiver admits of a lon∣ger Gage, instead of Mercury we may make use of a Tincture of Roses, or of Spirit of Wine with Cocheneel; in which, the Exsuction of the Air will be more nicely represented. Fifthly, We may vary the Mercurial Gage, by ordering the shorter Leg, so that it may have a Bubble

about half an Inch Diameter, at an Inch distance from the Basis of that Leg, which Bubble must have a Pipe upon the upper Part of it to give way to the Air; which Bubble hath this Ad∣vantage above the other, that less Air may be contain'd in the Top of the longer Leg; since the Mercury not being capable of being rais'd so high, the Rarefaction of the included Air will be render'd more apt to be estimated by the Eye. Sixthly, This Gage is much more useful than those mention'd by other Authors, because it gives us an Account of the several Degrees of the Air's Rarefaction.

EXPERIMENT XX. An easie way to make the Pressure of the Air sensi∣ble to the Touch.

* 1.156THE Pressure of the Air will be made sen∣sible to the Touch, if a Tapering Tube of Brass, whose Cavity at one end is an Inch, and the other two Inches and an half wide, be fix'd to the Pump instead of a Receiver; for if when the larger Orifice is Cemented on the Pump, one presses the Palm of ones Hand upon the smaller Orifice, and the Pump be set on Work, it will be a difficult Matter to take off ones Hand, and not a little painful; but the Pressure of the Incumbent Atmosphere will have a much more sensible Effect, if the larger Orifice be upwards instead of the smaller.

EXPERIMENT XXI, About the subsiding of Mercury in the Tube of the Torrecellian Experiment, to the Level with the Superficies of the Stagnant Mercury.

THE lower Part of the Ball of a Bolt-head being circularly cut off, we made use of it for a Receiver, including a Baroscope in it, and upon the first Exsuction, the Mercury subsided from 29 Inches to 9 or 10, and by three Exsu∣ctions more, would be brought to a Level with the Stagnant Mercury, but would rise to it's first Station again, as the Air was admitted in flower or faster.

In which Experiment it is to be noted; First, that upon the first Exsuction, the Mercury was brought within an Inch of the Bottom, and con∣tinu'd several successive Vibrations before it set∣led at 10 Inches high. Secondly. If instead of drawing any out, Air be forced into the Recei∣ver, it will raise the Mercury higher than it's former Station: Thirdly, The Receiver was so far exhausted, as to make the Mercury subside to a Level.

EXPERIMENT XXII. In Tubes open at both Ends, when Nature's Abhor∣rency of a Vacuum cannot be pretended, the Weight of Water will impell Quicksilver no higher in slender than in larger Pipes.

* 1.157TO prove that the Weight of the Atmos∣phere, may buoy up Mercury equall in large as in smaller Tubes, I shall add the following Tryals.

The I. TRYAL.

Having put as much Mercury into a Glass Tube, about two Foot and a half long, as reach'd 3 or 4 Fingers, the one End being seal∣ed Hermetically; we hung two Tubes by Strings to the Top of the former, so that the lower Ends of them were immers'd in the Mercury; which being done, we pour'd Water upon the Mercury, and observ'd the Mercury to be equally rais'd in the great Pipe, as in the little one, and the Water being suck'd out, it proportionably subsided in each.

The II. TRIAL.

Having pour'd a Convenient Quantity of Quicksilver into a Tube of Glass, near a Foot long, and filled two Pipes of Mercury of an un∣equal Bore, the one End of each being Hermetically seal'd, we immers'd them in the large Tube, contriving to open the lower Orifice, when be∣low

the Stagnant Mercury; and I observ'd, that they not only both of them subsided to an e∣qual Station; but Water being pour'd upon the Stagnant Mercury, the Weight of it buoy'd them up both alike in the Tube, and the Water be∣ing successively suck'd out, and put in again, the the Mercury in the Tube, proportionably fell and rose equally in both; no difference proceeding from the Wideness of their Diameters, in the Height of the Mercurial Cylinders.

EXPERIMENT XXIII. At what Height Mercury Amalgamated with Tin, as well as pure Mercury, will be suspended.

HAVING fill'd a Glass Tube with Mercu∣ry Amalgamated with Tin, and inverted it, it did not fall below 31 Inches. In trying this Experiment, the following Particulars are to be noted:

• First, That if the Amalgama be too thick, it will be apt to stick to the Tube, and will likewise hinder several Aerial Corpuscles from flying away.
• Secondly, From hence it may be observ'd, that as the Aequilibrium of Mercury, and the Atmosphere varies; so does it's Ascent in such Tubes.
• Thirdly, It would not be amiss here to consider, whether these two Metals penetrate each others Dimensions, as I have observ'd Copper and Tin to do; and by forming a new Metalline Substance to render the Composition heavier than the Weight of the two single Ingredients.

EXPERIMENT XXIV. A Method of making Barometers, which may be carried to distant Countries.

TO make a Portable Barometer, we took a Cylinder about 4 or 5 Foot long, and ha∣ving bent one End at the Flame of a Lamp, so as to make the shorter Leg about a fourth Part as long as the other, sealing up the End of the longer Leg, we injected Mercury into the short∣er Leg by a Tunnel, till it was rais'd about 3 Inches in both Legs; which being done, and the Orifice of the shorter Leg being stopp'd with the Finger, we inclin'd the longer Leg, and so by successively filling the short Leg, and inclining it so as to make it run into the longer, we fill'd the longer Leg quite full of Mercury, and by incli∣ning it several times afterward, and permitting the Bubble of Air, which usually lies at the Top of the seal'd Head, to run through the Mercu∣rial Cylinder backwards and forwards, we freed it from those Bubbles, which are usually in it's Pores. But besides this way of filling the Pipe, we have, with less Trouble, done it by making use of a Tunnel; which, when the Pipe is a lit∣tle inclin'd, reaching a little above the Flexure of the Syphon, will fill the Tube without much trouble: And the Pipe thus fill'd with Mercury may, by often erecting of it, and shaking the Pipe so erected, be freed from those Aery Particles which commonly lodge in the Pores of the Mercury.

* 1.158The Barometer being thus order'd, we con∣triv'd a Frame to carry it in, which was made of a Piece of Wood, in which a Gutter was cut for the Pipe to lie in; the lower End of the Frame being likewise so contriv'd, as to contain the short Leg of this Tube: The Pipe being lodg'd in this Gutter, we fix'd a Cover to one side of the Frame, with little Highes; the o∣ther, when occasion requir'd, being fastned with Hasps.

And because the Motion the Mercury would be put into, would be apt to break the Pipe, were there too much Liberty given it to move in, or were there any Interstices betwixt the Pipe, and the Gutter it is lodg'd in; we took Care to lay Cotton both betwixt the Pipe and the Concave of the Frame, and betwixt the Co∣ver and it; and that the empty Space which is usually above the Surface of the Mercury in Ba∣rometers, might not be prejudicial, we took Care to invert the Tube, and to fill the remaining Space unpossess'd with Mercury either with an Addition of Mercury or with Water, sealing up the Orifice of the shorter Tube Hermetically, till it came to be us'd again; and then, the Super∣flous Mercury, may be taken away by immer∣sing a small Pipe in it; which, if the upper O∣rifice be stopp'd with ones Finger, will take a∣way so much as the Cavity of the immers'd Tube had receiv'd into it: But if Water be made use of, instead of Mercury, it may be lick'd up with a Spunge. And if by shaking of this Barome∣ter in long Journeys any Particles should get out of the short Leg into the larger, by successively inverting the Tube, and permitting the Bubble

of Air to pass backwards and forwards, the Mercury in the long Tube may easily be freed from Bubbles.

Of what Use this Barometer may be, in dis∣covering the Weight of the Atmosphere in long Journeys, both at Sea and at Land, I shall leave to others to consider; only I shall annex this Ad∣vertisement, that sometime after I made this Ba∣rometer, having carri'd it about 33 Miles I ob∣serv'd, that it did not rise by ¼ of an Inch as high as it did before; but whether it might be impu∣ted to the narrowness of the Pipe, or any other Accident, I cannot yet determine.

EXPERIMENT XXV. What Height the Mercury in Barometers will be suspended at, at the Top of Hills. Some Obser∣vations of the Height of Mountains, especially, the Pic of Teneriff.

HAVING observ'd the Height at which Mercury was suspended at the Bottom of a Hill, and compar'd it with a Barometer made the ordinary ways; it was observ'd, that the Height it was suspended at, at the Top of the Hill, was ¼ part of an Inch below the Mark it reach'd at the Latter; and as the Barometer was brought lower, the Mercury in the Pipe rose higher and higher: But if such Observations could be made at the Top and Bottom of the Mountain Teneriff, the Experiment would afford further Proof of our Hypothesis concerning the Air's Spring and Weight.

An Appendix about the Height of Mountains.

* 1.159NOtwithstanding some Ingenious Men have taught, that the Height of the Atmosphere is of stupendious, and others confine it to narrower Dimensions; yet, I shall add some Observations, which may confirm what we have taught concerning it; and tho', as Ricciolus takes notice, the Jesuit Rector Melensius says, that of all the Clouds, whose Height he measur'd, they did not exceed 5000 Paces, yet if we allow Me∣teors and Comets to arise from Terrene Exha∣lations, and that the Height of Clouds varies according to the different Degrees of the Air's Rarefaction, it will follow, that the Height of most of them exceeds what Carden and Kepler allow.

But to proceed to what I have to relate con∣cerning the Height of Mountains; I shall re∣late, what I have learn'd by Information. And first, the Ingenious Mr. Sydenham told me, that the Mountain Teneriff is so high, that the Top of it may be seen 60 Leagues off, and that he himself had discover'd it at 40 Leagues distance like a blew Pyramid above the Clouds; and he likewise told me, that the Island of Madera might be seen from it, tho' 70 Leagues distant; and that the Great Canary seem'd so near it, that one would think it possible to leap down upon it: And indeed, Ric••iolus observes, that it might be seen 4 Degrees distance; and Snellius also al∣lows the Height of it to be Ten Miles; tho' I believe, that the way he takes to calculate the Height of it, may be none of the truest; he

likewise by Refraction, judging the Mountain Caucasus to be 51 Bolonian Miles high, which is not believ'd probable; since the Mountain Teneriff hath been observ'd, by one who took it's Height in a Ship at Sea, not to be above 7 Miles high in a Perpendicular Line, yet it is esteem'd the highest Mountain in the World; tho' if what Aristotle and others report of Mount Caucasus, be true, there may be others much higher than those. For tho', if measur'd from the Foot, or Level of that piece of Ground, which they stand on, they may be lower, yet considering that the Ground they stand on, may be much more protuberant, from the Level Superficies of the whole Globe, they may be much higher upon that Account.

EXPERIMENT XXVI. The Pressure of the Atmosphere may be able to keep up the Mercury in the Torrecellian Experiment, tho' the Air presses upon it, at a very small Orifice.

IT being observ'd by several Learned Men, That Mercury is suspended at an equal height in a close Room, as in the open Atmosphere; to prove, that the Air having a Communication with the External, even at small Crannies, may have an equal Force, as if the Mercurial Cylin∣der was immediately subject to the whole Atmo∣sphere; I shall add, That if the Tube, just before mention'd, for a Portable Barometer, be so drawn out at the Flame of a Lamp, that the Orifice is but about a tenth Part as big as before, the Mer∣cury will be suspended at the usual Height; and the like will succeed, if instead of drawing the

End of the Pipe out so, a Cork be put into the End of the Tube, leaving but a small part of the Orifice open to the Outward Air.

EXPERIMENT XXVII. An Oblique Pressure of the Atmosphere may be suffi∣cient to keep up the Mercury at the usual Height, in the Torrecellain Experiment, and the Spring of a small quantity of Air may do the same.

IF the the Shorter Leg of a Syphon,* 1.160 being bent, as represented by Fig. 3d. Plate the VII^th the Mercury be suspended at it's usual Height, it ap∣pears that the Pressure of the Atmosphere hath as strong Effects, if the End of the Tube, through which it is convey'd, only admits of the Pressure of the Air, which it receives downwards.

But if instead of being so bent,* 1.161 the End of the Shorter Leg be Hermetically seal'd, as represent∣ed Fig. IV. Plate the VII. the Mercury is sustain'd at it's usual Height, it will appear, that the Spring of a small quantity of Air is able to bear up a Cy∣linder of Mercury.

N. B. If the Tube thus Hermetically seal'd, be shaken, the Mercury will form some Vibrations upon the Included Air; the Spring of it being compressed, and expanded again successively for a while.

But the former of these Tryals may be made in a Pipe, conveniently shapen before the Longer Leg is fill'd with Mercury, and the latter by stop∣ping the Orifice with a Cork, and Close Cement, which may be pierc'd with a Wire, when this is

us'd as a Baroscope; which way may be taken with a Travelling Baroscope.

EXPERIMENT XXVIII.

* 1.162TO shew that the Suspension of Mercury in a Glass Tube, less than 30 Inches long, does not proceed from a Fuga Vacui, I caus'd one to be Hermetically seal'd at one End, the Length of it being about two Foot and a half; and fill'd it with Mercury, a small quantity of Water be∣ing left upon it; and when the Atmosphere was much lighter, I found that the Mercury subsi∣ded, and that there appear'd a small Bubble of Air in the Water, which being no bigger than a Pin's Head, was so far compress'd before, as not to appear.

EXPERIMENT XXIX. The Ascension of Liquors in very slender Pipes, in an Exhausted Receiver.

HAving tinged Spirit of Wine with Cocheneel, which bubbled in the Exhausted Receiver, for some time, several slender Pipes being put into it, it rose highest in those whose Bore was narrowest; but when the Air was let in again, the Liquor in both subsided to a Level: But two Pipes of different Bores, being let down into that Liquor a second time, tho' it answer'd the for∣mer Tryals in the Ascent; yet, the Surface in the slenderer Pipe, remain'd something above the other, when the Air was let in again. But what was more Remarkable, was, that tho' the

Liquor in the Vessel, in this Tryal, emitted no Bubbles, yet that in the Ends of the Tubes did; which were suppos'd to be caus'd by the sides of the Glass, they were contain'd in.

EXPERIMENT XXX. When the Pressure of the External Air is taken off, it is very easy to draw up the Sucker of a Syringe, tho' the Hole at which the Water should succeed, be stopp'd.

FOR a further Illustration of the Doctrin of the Spring and Weight of the Air, we made the following Tryals.

The I. TRYAL.

We took a Syringe of Brass (see Plate 8th. Fig. 1st.) whose Barrel was about six Inches long,* 1.163 and it's Diameter about one Inch ⅜, and having fitted the Sucker to the Barrel of the Syringe, we stopp'd the lower Orifice of the Syringe, and ty'd a good Weight to it; which being done, we let it down into the Receiver, ty∣ing a String to the Sucker, and another End of that String to the Turning-Key in the Cover of the Receiver; where we observ'd, That tho' when the Receiver was exhausted, we could, by turning the Key, draw up the Sucker easily; yet, when the Air was admitted into the Receiver again, it could not be lifted up with a less Force, than what was sufficient to overpower the Pres∣sure of the Atmosphere, or the Air contain'd in Receiver; but the Air being once let in, when the Sucker was rais'd to the Top of the Barrel, the Pressure of it was so violent, as, by forcing

the Sucker down into the Barrel of the Syringe, to break the String, which was ty'd to the Turn∣ing-Key.

The II. TRYAL.

Being a Variation of the former.

We took the former Syringe, and having ty'd a Weight, which weigh'd about two Pound and two Ounces, to the Sucker, we suspended it in our Receiver, the Orifice of the Barrel being first stopp'd with a Cork; and we observ'd, that after a few Exsuctions, the Weight drew down the Bar∣rel of the Syringe; and when the Air was again let in, the Pressure of it rais'd it up much faster than it fell.

But in this Experiment, it is to be noted, that if Air gets into the Barrel of the Sucker, whilst it is drawn down, it will not be rais'd quite so high again as before. And likewise, the Reason why it is requisite, that so large a Weight should be ty'd to draw it down, is because it must not only overpower the Pressure of the Air, but also the Straitness which requires a Force to make the Sucker move in the Barrel.

Secondly, it is observ'd, that as the Weight did not overpower the Pressure of the Air, till a good deal was exhausted; so neither did it rise again, till a sufficient Quantity of Air was let in again.

EXPERIMENT XXXI. About the opening of a Syringe, whose Pipe was stopp'd in the exhausted Receiver, and by the help of it, making the Pressure of the Air lift up a conside∣rable Weight.

HAving clos'd up the Hole at the Bottom of the Syringe,* 1.164 with good Cement, we ty'd a hollow piece of Iron to the Barrel, into which several Weights being put, we ty'd the Rammer to the Turn-Key; and tho', when the Receiver was exhausted, we could draw up the Rammer without the Syringe; yet, upon a Reingress of Air, the Syringe and the Weights would be rais'd swiftly up: So that so small a Cylinder of Air as equalled the Barrel of the Pipe, was able to lift up the Weight of sixteen Pounds.

EXPERIMENT XXXII. The Sticking of Cupping Glasses depends on the Pressure of the Air.

TO make it evident,* 1.165 that the Sticking of Cup∣ping Glasses, and the Pain which they cause, proceeds from the Pressure of the Air, we provided a Receiver, and a Large Glass, such as Plate the 8th. Fig. 3d. delineates; I caus'd the Cupping Glass to be apply'd to a Young Man's Hand; which being done, and his Hand apply'd to the Top of the Receiver, in∣stead of a Cover, the Lower Orifice of the Re∣ceiver, having first been cemented on the Pump,

upon the first Exsuction of the Air, the Cupping Glass fell off his Hand, for want of the Pressure of the External Air, to press against it.

EXPERIMENT XXXIII.

TO illustrate the former Experiment, we took a Brass Hoop, mention'd in the Fifth Ex∣periment, and stretching a Bladder upon the up∣per Orifice of it, as upon the Head of a Drum, we ty'd it up in the Middle of the lower Orifice,* 1.166 and placing it upon a piece of Wood, which had a hole in the Middle for the Neck of the Bladder to hang through, we made several holes on the Lower Side of that Bladder; which being done, we suspended a Blind-head at the Turn-Key of our Receiver, and when the Receiver was exhausted, we let it down to the Bladder, and found, that when the Air was again admitted into the Re∣ceiver, the Pressure of it so press'd upon the Bladder, as to fix it fast to the Blind-head.

But repeating the Experiment, and exhausting the Receiver more perfectly, we took out the Bladder thus fix'd to the Blind-head, and having ty'd the Glass to the Hook of a good Statera, and likewise a large Scale to the Neck of the Bladder, and put in Weights into it, till they amounted to 35 Pound weight; then the Weight, over∣poising the Pressure of the External Air, the Bladder fell off: But in this Experiment it was observ'd,* 1.167 that as the Weights in the Scales grew heavier and heavier, the Bladder seem'd to be suck'd more and more into the Receiver.

EXPERIMENT XXXIV. Bellows whose Nose is very well stopp'd, will open of their own accord, when the Pressure of the Exter∣nal Air is taken off.

AS an Argument of the great Force of the Air's Weight, it is observ'd, that when the Nose of a Pair of Bellows is stopp'd, it re∣quires a Force able to overpower the Pressure of so large a Pillar of Air, as lies upon them, to open them; but when that Weight of the Atmosphere is taken off, the Spring of the Included Air is so strong, as to be able to raise and expand the Bellows of it's own accord.

To make this Evident,* 1.168 we caus'd a Pair of Bellows to be made, whose Boards were circu∣lar, and near 6 Inches Diameter, without a Valve, the Nose of them being about an Inch long, and the Leather limber: Which Bellows, when full of Air, seem'd to be a Cylinder of about 18 Inches high.

The Nose of these Bellows being stopp'd, when they were empty'd of Air, we convey'd them into our Receiver, and observ'd, that when the Air was exhausted out of the Receiver, the Air con∣tain'd in the Folds of the Bellows, and betwixt the two Bases lifted up the Higher a considerable Height.

EXPERIMENT XXXV. An Attempt to examin the Motions and Sensibility of the Cartesian Materia Subtilis, or the Aether, with a Pair of Bellows, which were made of a Bladder, in the exhausted Receiver.

IN order to try, whether there be any finer Substance than Air, in the exhausted Recei∣ver, we contriv'd to make a Pair of Bellows of a Bladder, whose Bases were Paste-board,* 1.169 the up∣per being cover'd with a Plate of Pewter, to which was fix'd a Leaden weight to press it down: Besides, over against the Nose of the Bel∣lows, in which the Neck of the Bladder ter∣minated, it was contriv'd, that the End of a Feather was fix'd so, that if any Subtle Matter were forc'd out of the Bellows, it should disco∣ver it self by moving that Feather.

The Bellows being thus provided, and the Pillars, to which the Feather is fastened, being joyn'd to the upper Basis of the Bellows, with Cement, we fix'd a Weight to the Lower Basis, and convey'd it into the Receiver;* 1.170 where we observ'd, upon the exhausting of the Receiver, that the Air in the Bellows rais'd up the upper Basis, together with it's Weight; and the Air rising out at the Vent, manifestly mov'd the Fea∣ther: But when the Receiver was quite ex∣hausted, and the Weight upon the Upper Basis depress'd it violently, we could not perceive that the Feather was in the least mov'd, and the like was observ'd upon repeating the Experi∣ment.

EXPERIMENT XXXVI. The great and seeming Spontaneous Ascent of Water, in a Pipe filled with a Compact Body, whose Par∣ticles are thought incapable of imbibing it.

WE took a slender Pipe, and having ty'd a Linen-cloth to the Iower Orifice, we fill'd it with Minium; and immerging it in Water in a Wide-mouth'd Glass about an Inch, the Water ascended about 30 Inches; and the Experiment being again repeated in another, it rose 40 Inches.

In which kind of Experiments, the following Particulars were to be observ'd: First, That other Powders being made use of instead of this, the Experiment did not succeed so well; nor was the Success much better, when we made use of Ink instead of Water.

Secondly, Our Experiment succeeded the bet∣ter, the finer and closer the Minium was: But if the Pipe be too small, the Event will not always be successful.

Thirdly, We observ'd, That the Water ascends not to it's utmost, under 30 Hours, and some∣times longer.

Fourthly, From hence it appears, That the Wa∣ter in our Tube rose, without any swelling of the sides of the Tube, which some Learn'd Men a∣scribe the Cause of Water's Rising in Filtres to.

Fifthly, From hence it may be urg'd, as pro∣bable, That the Sap in Trees may rise after the like manner, being promoted by Heat, and a due Texture of Parts.

EXPERIMENT XXXVII. Of the seeming spontaneous Ascent of Salts, along the sides of Glasses, with a Conjecture at the Cause of it.

I Have several times observ'd, that the watery Part of a Solution of Sea-Salt or Vitriol, be∣ing evaporated, the coagulated Salts would creep up the sides of wide-mouth'd Glasses, in which the Solution was contain'd; and not only so, but if the Experiment were longer continu'd, they would rise over the sides of the Glass, and cover the external Superficies with a Crust of Salt.

As for the Cause of so strange a Phaenomenon, tho' I will not be positive in it; yet, it may not improbably depend on the like Cause, as the As∣cent of Water in the Tube, mention'd in the foregoing Experiment.

For we may observe, that the Edges of Water are not only above the Superficies of the rest of the Water; but Sea-Salt as well as several others, chrystallize at the Top of the Liquor they swim in, and near the sides of the Glass, their Coa∣gulation being promoted by the Coldness of it; which Salts, when once the sides of the Glass is beset with them, the Water may rise to the Top, for the same Reason that it does in the slender Pipe before mention'd, and Salts carri'd up to the Top of those, and coagulating there, still lay a further Bottom for their Ascent; and so successively, till they rise to the Top of the Vi∣ol: And that there are Passages betwixt these sa∣line Parts, for the Water to ascend through, ap∣pears; since they may be broke off in Flakes,

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separate from each other: And if it should be thought, that the Water in such an Ascent, would dissolve the Salt; it may be answer'd, that the Water being so much impregnated with Salt already, can imbibe no more; and conse∣quently, for that Reason, when it runs down the outsides of the Vessels, coagulates by the way, being too thick and full of Salts to conti∣nue long fluid.

EXPERIMENT XXXVIII. An Attempt to measure the Gravity of Cylinders of the Atmosphere, so that it may be known and express'd by common Weights.

* 1.171BEING desirous to know what was the Weight of an Atmospherical Cylinder of Air, of a determinate Diameter, I caus'd a Pipe to be made of Brass, whose Diameter was an Inch, and it's Length three; one End of which being clos'd up with a Plate of Brass, I counter∣pois'd it in a nice pair of Scales; and found, that it was able to contain about 137 Drachms 45 Grains of Mercury; which being multiply'd by Tens, a Cylinder of Mercury of 30 Inches, and consequently an Atmospherical Cylinder able to counterpoise it, must amount to 12 Ounces and about 6 Drachms. And by weighing Wa∣ter in this Tube, before the Mercury was put into it, the Water weighing 10 Drachms 15 Grains, the Proportion of Water to Mercury seem'd as 13 18/41 to 1.

But in estimating the Weight of a Cylindri∣cal Pillar of Air, it may be here requisite to advertise, that I made use of a Brass Cylinder, because the Cavities of a Glass Tube are unfit

for such an Experiment; since it is a hard thing to know, whether the Bore of such Tubes be e∣qual throughout their Diameter.

The Weight of a Cylinder of Mercury be∣ing thus found, it will not be very difficult to know, the Weight of a Cylinder of a different Diameter, by the Assistance of the Doctrin of Proportions and the 14th Proposition of the 12th Book of Euclids Elements. For since according to that, Cylinders of equal Bases, are to one another as to their Heights; and since, by the second Proposition of the same Element, such Circles as the Bases of Cylinders, are to one another as the Squares of their Diameters; and since Mercurial Cylinders will bear the same Proportion in Weights as they do in Bulk; The Rule will be, That as the Square of the Diame∣ter of the Standard Cylinder, is to the Square of the Diameter of the Cylinder propos'd, so will the Bulk of the former be to that of the latter; and the Weight of that to the Weight of this; so that the Square of one Inch being 1, and the Square of 2 being four, the Weight of the lat∣ter will be four times the Weight of the for∣mer.

EXPERIMENT XXXIX. The Attractive Virtue of a Load-Stone in the Ex∣hausted Receiver.

TO try how far the Account given of the Attraction of a Load-Stone, depended on what some Modern Philosophers teach, viz. That the Effluvia of a Load-Stone pressing away the Air betwixt the Body attracted, that Air helps the Attraction, by pressing against the op∣site

side of the Stone; We plac'd a vigorous Load-Stone in our Receiver, having adapted a Cap of Steel to it, to the lower side of which, a Scale with 6 Ounces of Troy Weight was fix'd, which being all the Load-Stone, besides the Steel and the Scale was able to keep up (all which be∣ing suspended at a Button, which was on purpose on the inside of the Cover of the Receiver) we observ'd, that tho' the Receiver was exhausted as much again as in common Experiments; yet, the Load-Stone sustain'd it's Weight almost as firmly as before the Pump was ply'd; and the Reason why it was not altogether, was, the thinness of the Medium; since the Weight sus∣pended must be heavier, when the Air which was nearer proportion'd to their Weight was exhausted.

FINIS.

Notes

• * 1.1

  Qualities proceeding partly from the Influence of outward Agents; as well as the Primary Affections of Matter
• * 1.2

  Our Notion of Cosmical Qualities grounded on the three following Propositions
• * 1.3

  Proposition the first.
• * 1.4

  The second Proposition.
• * 1.5

  The Expan∣sive force of Beans soa∣ked with Water.
• * 1.6

  Several Phaenome∣na produc'd by Virtue of Motion in the Parts of the Air.
• * 1.7

  The Esta∣blish'd Laws of the Universe Contribute to the pro∣ducing of several Phaenome∣na.
• * 1.8

  How a Bar of Iron ac∣quires Mag∣netical Qua∣lities.
• * 1.9

  The Third Proposition.
• * 1.10

  Suspicion the First.
• * 1.11

  A Second.
• * 1.12

  A Third.
• * 1.13

  The Fourth.
• * 1.14

  Considera∣ble Variati∣ons in the Temper of Climates.
• * 1.15

  An Obser∣vation con∣cerning Manna.
• * 1.16

  Another Suspicion
• * 1.17

  Another Suspicion.
• * 1.18

  A very con∣siderable Phaenome∣non rela∣ting to the Sun.
• * 1.19

  Nature may not always be exact in her Laws.
• * 1.20

  Vortices be∣yond the Concave Surfaces of the Firma∣ment.
• * 1.21

  The Temper of the Air in Groves.
• * 1.22

  The Tempe∣rature of Subterrane∣al Regions consider'd under cer∣tain Propo∣sitions. Prop. I.
• * 1.23

  Prop. II.
• * 1.24

  Member the first.
• * 1.25

  Why the Middle Re∣gion is cold∣est.
• * 1.26

  The second Member of the second Proposition.
• * 1.27

  The diffe∣rent Temper of Subter∣raneal Re∣gions may be varied by the Soyl.
• * 1.28

  Prop. III.
• * 1.29

  The effects of Subter∣raneal Fires.
• * 1.30

  Whence the Unusual Heat in some Mines proceeds.
• * 1.31

  Submarine Regions two.
• * 1.32

  The Tempe∣rature of the Upper∣most.
• * 1.33

  The Tempe∣rature of the Lower Region.
• * 1.34

  The Bottom of the Sea very Rough and Une∣qual.
• * 1.35

  The Gravi∣tation of the Water.
• * 1.36

  The Bottom of the Sea not disturb∣ed in Storms
• * 1.37

  The Water at the Bot∣tom of the Sea almost stagnates.
• * 1.38

  Observati∣ons relating to Coral.
• * 1.39

  Trees un∣der Water.
• * 1.40

  The Inva∣lidity of the Cause as∣sign'd by the Peripa∣teticks.
• * 1.41

  The propor∣tion of Salt to Water.
• * 1.42

  Springs in the Bottom of the Sea.
• * 1.43

  The Reason of the Salt∣ness of the Sea.
• * 1.44

  The Bitter∣ness of Sea Water, whence.
• * 1.45

  Agitation requisite to preserve Sea Water from stinking.
• * 1.46

  The Saltness of the Sea differs.
• * 1.47

  The Propor∣tion of Salt in Sea-Wa∣ter.
• * 1.48

  The Sea-Water salt∣er some∣times than at others.
• * 1.49

  The danger of an ill use of Mineral Waters.
• * 1.50

  The Effects of filings of Steel, in a Tincture of Galls.
• * 1.51

  Quaeries in order to a discovery of the Virtues of Mineral Waters.
• * 1.52

  A Continu∣ation of Qeaeries.
• * 1.53

  Observati∣ons requi∣site in Try∣ing Mine∣ral Waters.
• * 1.54

  Whether Mineral Waters have Arse∣nick dissol∣ved in them
• * 1.55

  What Pro∣portion of Salt Mine∣ral Waters afford.
• * 1.56

  The Com∣mon Distin∣ction be∣twixt Na∣tural and Preternatu∣ral States ill grounded
• * 1.57

  Ice a Na∣tural State in some Places.
• * 1.58

  A forced State, the Natural State of the Air.
• * 1.59

  A Descrip∣tion of the Pneumati∣cal Engin.
• * 1.60

  The Method of Mana∣ging the Pump.
• * 1.61

  A Springi∣ness in the Air.
• * 1.62

  Why Mer∣cury is sus∣pended higher at the bottom than the top of a Hill.
• * 1.63

  The Air presses upon the sides of Bodies it encompas∣ses.
• * 1.64

  The Air en∣closed in the Receiver Acts by vir∣tue of its Spring.
• * 1.65

  What Weight is requisite to draw down the Sucker.
• * 1.66

  The Expan∣sion of Air in a Lamb's Bladder in our Receiver
• * 1.67

  The Force of the Airs Ex∣pansion.
• * 1.68

  The Airs Expansion measur'd.
• * 1.69

  The former Experiment illustrated.
• * 1.70

  A Confir∣mation of the former Experi∣ment, &c.
• * 1.71

  Of the Flame of a Candle in a Receiver.
• * 1.72

  Concerning the Burning of a Match.
• * 1.73

  The Reason of the afore∣mention'd Effect.
• * 1.74

  Gun-pow∣der explo∣ded in Va∣cuo Boylia∣no, &c.
• * 1.75

  The Opera∣tion of a Load-stone.
• * 1.76

  The Gravi∣ty of the Air, &c.
• * 1.77

  Concerning a Vacuum.
• * 1.78

  The Reasons why Mercu∣ry is not al∣ways equal∣ly suspend∣ed.
• * 1.79

  Considera∣ble Changes in the Qua∣lities of the Air.
• * 1.80

  The subsi∣ding of a small Cy∣linder of Water.
• * 1.81

  Conceening the Elater of Water.
• * 1.82

  Concerning the same.
• * 1.83

  The Bubbles which rise in Water, Aerial, pro∣ved.
• * 1.84

  The Expan∣sion of Wa∣ter depends on the Ela∣ter of the Air lodg'd in its Pores.
• * 1.85

  Whether Air be a primogene∣al bedy or not?
• * 1.86

  See Figure the 15th.
• * 1.87

  The Subject of the for∣mer Expe∣riment pro∣secuted.
• * 1.88

  The former Experi∣ments pro∣secuted with other Liquors.
• * 1.89

  Concerning the Air's Gravity, and Expan∣sion under Water.
• * 1.90

  Concerning the Vibra∣tions of a Pendulum.
• * 1.91

  Concerning the Propa∣gation of Sounds.
• * 1.92

  The Erup∣tion of Bub∣bles from Water, upon the remo∣val of the Air.
• * 1.93

  The reason of the A∣scent of Fumes and Vapors.
• * 1.94

  The Nature of Fluid Bo∣dies illu∣strated by Smoak.
• * 1.95

  Concerning the Cohae∣sion of Flat Bodies.
• * 1.96

  The Pressure of the out∣ward Air, on a Valve fix'd to the External Orifice of the Stop-cock.
• * 1.97

  The weight of the At∣mosphere consider'd.
• * 1.98

  What weight the Atmosphere is able to raise, sus∣pended at the Sucker.
• * 1.99

  Considera∣tions con∣cerning a Vacuum.
• * 1.100

  Attempts to weigh light Bodies in our Re∣ceiver.
• * 1.101

  The Cause of Filtration.
• * 1.102

  The Weight of the Air.
• * 1.103

  The Pene∣trating power of some Spirits above that of the Air.
• * 1.104

  Why the Parts of the Air are more indispos'd to pass through the Pores of some Bodies than others.
• * 1.105

  The force of the Air's Expansion.
• * 1.106

  The Weight of the Air.
• * 1.107

  Proportion betwixt the Weight of Air and Water, &c.
• * 1.108

  Conjectures concerning the Height of the At∣mosphere.
• * 1.109

  See Plate the First.
• * 1.110

  The Weight of an equal Proportion of Air and Mercury.
• * 1.111

  Of the free∣zing of Water and it's Expan∣sion.
• * 1.112

  A Phaeno∣menon ta∣ken notice of in the exhausted Receiver.
• * 1.113

  Whether Rarify'd Air will su∣stain Flying Insects.
• * 1.114

  Concerning Respiration.
• * 1.115

  The diffe∣rent Opera∣tions of Cor∣rosives in, and with∣out our Re∣ceiver.
• * 1.116

  Of the spon∣taneous E∣bullition of warm Li∣quors.
• * 1.117

  The first Argument of Francis∣cus Linus Answer'd.
• * 1.118

  A snd Objection.
• * 1.119

  A third. Objection answer'd.
• * 1.120

  Another Objection answer'd.
• * 1.121

  Arguments in favour of the Funi∣cular Hypo∣thesis exa∣min'd.
• * 1.122

  The Aristo∣telian Noti∣on of Rare∣faction re∣jected.
• * 1.123

  The Height of Mercury suspended at the Top of a Hill.
• * 1.124

  See Fig. the First, Plate the Second.
• * 1.125

  See Fig. the Sec. Plate the Second.
• * 1.126

  The Air's Condensa∣tion mea∣sur'd.
• * 1.127

  See Fig. 4. Plate 2.
• * 1.128

  The Air's Rarefaction consider'd.
• * 1.129

  The reason why Air condens'd by Cold, does not raise Mercury e∣qually, as when con∣dens'd by Pressure.
• * 1.130

  See Plate the Second.
• * 1.131

  Rarefaction according to the Doctrin of the Ple∣nists.
• * 1.132

  Elasticity explain'd by the Carte∣sian Hypo∣thesis.
• * 1.133

  See Plate the second Fig. 5.
• * 1.134

  Our Au∣thor's Ex∣plication of the Rota Aristotelica.
• * 1.135

  The Spring of the Air proved.
• * 1.136

  The exhau∣sted Recei∣ver void of Air.
• * 1.137

  Why Ani∣mals die in the Exhau∣sted Recei∣ver.
• * 1.138

  The Pressure of the Air upon Bodies contain'd in it, prov'd.
• * 1.139

  See Fig. 6. Plate second
• * 1.140

  Motion the Chief Qua∣lification in order to Fluidity.
• * 1.141

  See Plate the Third and Fourth.
• * 1.142

  See Plate 5. Fig. 1.
• * 1.143

  An Argu∣ment a∣gainst a Fuga vacui.
• * 1.144

  See Plat. 6 Fig. 2.
• * 1.145

  See Plate 6. Fig. 3.
• * 1.146

  See Plate 6. Fig. 4.
• * 1.147

  A Bladder burst by the Spring of the Inclu∣ded Air.
• * 1.148

  Bubbles Hermeti∣cally seal'd, broke by the Air inclu∣ded.
• * 1.149

  The Force of the Air's Spring.
• * 1.150

  See Plate the 5. Fig. the 2.
• * 1.151

  See Plate the Fifth, Fig. the Third.
• * 1.152

  The Former Experi∣ment Illu∣strated.
• * 1.153

  The greatest Height to which Wa∣ter may be rais'd by Suction, &c.
• * 1.154

  See Plate the Seventh. Fig. 1.
• * 1.155

  See Plate 5•• Fig. 4.
• * 1.156

  The Pres∣sure of the Air sensible to the Touch.
• * 1.157

  The suspen∣sion of Quicksilver equal in small and wide Pipes.
• * 1.158

  See the whole Baro∣meter, Plat. 7. Fig. ig. 2.
• * 1.159

  The Height of Moun∣tains.
• * 1.160

  See Plate the 7th. Fig. the 3d.
• * 1.161

  See Plate the 7th. Fig. the 4th.
• * 1.162

  A Baro∣scope of use but at some times.
• * 1.163

  See Plate the 8th. Fig. 1st.
• * 1.164

  See Plate 8th. Fig. 2d.
• * 1.165

  See Plate 8th. Fig. 3d.
• * 1.166

  See Plate the 8th. Fig 4.
• * 1.167

  See Plate the 8th. Fig. the 5th.
• * 1.168

  See Plate the 8th. Fig. the 6th.
• * 1.169

  See Fig. the 7th. Plate the 8th.
• * 1.170

  See Fig. the Eighth.
• * 1.171

  The Weight of a Pillar of Air of a determi∣nate size.