The great and new art of weighing vanity, or, A discovery of the ignorance and arrogance of the great and new artist, in his pseudo-philosophical writings by M. Patrick Mathers, Arch-Bedal to the University of S. Andrews ; to which are annexed some Tentamina de motu penduli & projectorum.

THE GREAT AND NEW ART OF WEIGHING VANITY.

AS in combating, each party first intends his own defence, and in the second place only prepares an assault for his Antagonist: So I, before I make any attempt on my Ad∣versaries other Writings, shal endeavour to wipe off that durt which he hath thrown upon me, in the Postscript and Preface to his Hydrostatics.

I think it no wonder that my Adversary hath suppressed that Letter of mine, which he mentioneth in his Postscript, and I have printed in my Preface; for this gives him

the greater liberty to belie it; which he doth most splendidly, when he saith, that it is full of barbarous railings, passing all bounds of civility against himself, friends, and works: (whereas there is not a word of his friends in it: and what is therein said of his Works, the following Treatise will manifest, if it deserve the name of barba∣rous railings.) Nor is it strange to see one who wants truth on his side, make lies his refuge: But he may henceforth look for the common infelicity of liars, not to be be∣lieved, if he shal chance to stumble upon truth.

I had reason to fall upon his Ars mag∣na, &c. because I judge ex ungue Leonem, or rather, ex cauda Catum. Nor should the bare title have been past by, because it is arrogant and false, as shal be made to appear in its own place. I am unjustly in this com∣pared to blind Vejento; for he had the beast but at one hand; but to whatever hand I turn me, I find the beast there. And because my Adversary complains, that I have only snarled at the horse heels, I shal henceforth endeavour to pull the Ass from the sadle.

I excuse my Adversary for not inter∣preting

his Latin verses, because they were sent him from—without interpre∣tation.

I am obliged to his esteem, in supposing me a Master in an Ʋniversity. He was ne∣ver judged worthy of that dignity here: and by his ingratitude to Glasgow, he hath proven himself unworthy ever to have had it there, or any where else. And I wonder, that judging me a Master here, he should think strange that I am not so Pedantick, as (in imitation of him) to stuff my Letter with Latin Sentences altogether impertinent to our debate; and which in his Letter, and his review of mine, serve for nothing so much as to express his malice and virulency. Yea, there be two things which I think more then strange inconsideratness in him. The first is, that he accuseth me for not writing pertinent language in my Mother tongue; whereas in the very next page he writes, He hath done as the Ape did, that thrust the Cats foot into the fire, because he durst not do it himself; whereof, if he or—make good sense and Grammar, I shal give him back one of those Guinies which I am to have for everting his Theorems.

The other is, that he should challenge an Ʋniversity-man for writing a Letter with∣out a Latin Sentence, whereas he hath writ∣ten Volums of Mathematicks, without ever (for any thing I have yet seen) citing a Classick Mathematician, except once Euclid Prop. 24. lib. 1. El. Geom. in the 265. page of his Hydrostaticks, and that erro∣neously. For Euclid hath two sides in one triangle equal to two in another, and our Author hath only one side in each triangle. This is like the Tarsel of a Mathema∣tician.

I had reason to ask, Where are our doli & fallaciae, tabulae & testes, sapientia ad quam putamus nos pervenisse? For, first, none here being further concerned then in answering his importunat Letter, desiring the Ʋni∣versities encouragement for printing his Hydrostaticks; how could any so much as dream, that a man in his right wits, should provoke others to overthrow the title of a Book Tabulis & testibus, after he had once refused to let them know any part of what was contained in the Book? And yet this Author hath done it, as he himself testifies in the 310. page. Sure no other would, for

this dexterous wit is peculiar to him. But good Sir Sciole, let me tell you, it had been as great wisdom, either still to have concealed your great knowledge, or else to have kept up your provocations, whereby you should have saved me from the trouble of producing proof & witness against you, and your self from the shame of being con∣victed guilty of both Ignorance and Inso∣lence by them: For I assure you, that be∣fore your Indiscreet Challenges, I had no de∣sign to expose the folly of your arrogant pretences, and the contemptible infirmity of your acquittances, otherwise I might have drawn very lucky instances of both from your Ars magna & nova, &c.

Secondly, before he charged upon the Masters here his doli & fallaciae, there was nothing which could be a ground for it, seeing all that had past, was his Letter de∣siring their concurrence to the printing of his Book, and their answer, wherein they declare their mind with much candour and calmness. And he tacitly acknowledgeth the injustice of his challenge, in answering my question from that Letter in which the question it self is contained: For it is

against both Reason and Religion, first to calumniat, and then to justifie the calumny from something posterior thereto; and it is yet the worse in him, that he doth it by an untruth, in alledging my letter to have another design, then any, except himself, can discern; nor would he see it, if any other thing could be found to excuse his malicious reflexions upon persons of known integrity.

Thirdly, there are none among those whom he reproacheth, who have been so long at his School, as to learn either arro∣gantly to pretend to the knowledge of those things to which they are strangers; or vainly to fancy themselves knowing in that whereof they are ignorant.

After this, my Author proceeds in such a strain as would almost proyoke Meekness her self to make a Satyr. But it is so pitiful, that it cannot excuse a serious answer from being impertinent; and therefore I pass it, without suffering my self to digress into Satyrick reflexions upon his vanity therein. Only I beg his liberty, that since he hath made me the Cat, I may henceforth, with∣out offending him, catch the Rat as oft as he comes in my way.

Now my Adversary susficiently animat with rage, prepares himself for making a furious assault upon some passages of my letter, about perfection of Sciences, and be∣gins it very learnedly, by bringing in the Historical part of Geography, as a part of the Science of Geography; which is as good Lo∣gick, as if he had said, that black is a part of white, because they are both colours. But that he may the better understand this, I tell him, that Geography simpliciter is not a Science: for a great part of it is only Hi∣story: and I cannot suppose him so igno∣rant, as not to know that Science and Hi∣story (albeit all learning, as almost all things else, receive their denomination from the most noble part) are very different: Espe∣ccially in Mathematicks, where the scien∣tifical part is firm and Geometrical, and the Historical part subject to the weakness of our senses; the one consisting in Me∣thods and Demonstrations, the other in Pra∣ctises and Observations. All these things he here mentioneth, and thousands more, can be done by sure and Scientifick Methods, and therefore are perfected in so far as they are a Science; except only the measuring

the height of the Sea above the Earth; and this I think can only be done by himself, to whom it is easie to make Rivers run up∣wards, and so to work many wonders in Hydrostaticks. I am sure that any person who understands Logick, will find by these, that my Adversary hath triumphed before the victory, and hath unjustly called my argument a Fallacy, while he had only rea∣son to call it a Caption, since he was catcht thereby.

He next falls upon the Opticks, where after he hath vapored a little, to no other purpose then to display his Pedantry, and discover his dislike of modest expressions, he asketh a question which proves him a stranger to this part of learning. But that he may reap some instruction from this de∣bate, let him know that the Opticks hath scientifically so far perfected the sight, that it demonstrateth this Theorem: In all Te∣lescops, as the focus from the eye glass is to the distance of the focus from the object glass, so is the simple appearance of the object to the appea∣rance of the same through the Telescope. And therefore if the distance from the focus to the eye glass be one inch, and the distance

of the focus from the object glass 100000, the object will appear 100000. times lon∣ger or broader by help of the Telescope, then to the simple eye: Or with this Te∣lescope you may see as well at 100000. miles distance, as with the simple eye at one: If the glasses (or rather mirrours, because they lose no rays, and have caeteris partibus, all one determinat reflexion) be sufficiently large, and of the true Geome∣trical figure. By the same method, the de∣monstrative, or scientifick part, teacheth us to see at any finit distance, as if it were three foot or less. The like consideratis con∣siderandis, is true in Microscops and Scoto∣scops also. If our Author do question this rule, he shal find it in Escinardi Optica, and in the Philosophical Transactions, page 4005. as also in others before them both. It is like if he had known it, he had spoken bet∣ter sense in his New Optical experiment.

He is mistaken in saying, that it is not known how the sight is made; for it is done by bringing all the rays coming from one point of the visible alwayes to one point of the retina. It was never motioned by any learned man (since the Opticks came to this

perfection) that any brutes yet known, should see otherwise then men: Fishes in∣deed, because of the dense medium they live in, have their crystalline rounder; and night∣beasts, such as Cats and Owles, their uvea larger: yea, many other particulars there are, of which the Opticks do evidently de∣monstrat the reason.

Our Author might have remembred since he was a Professor of Philosophy, that lights and colours are qualities, at least ac∣cording to him; and therefore not the ob∣ject of any Mathematical Science, which is always quantity.

Reflexion and Refraction were fully han∣dled by Des Cartes; for it is out of doubt, That the angle of incidence is equal to the angle of reslexion, and the sines of the angles of inci∣dence proportional to the sines of the refracted angles. Infraction, is the same with Refra∣ction, and therefore impertinently re∣peated.

It is no wonder the Lord Verulam was not of my mind; for he died before the time of Des Cartes, who brought the Op∣ticks to this perfection. But it is no smal wonder to find a man pretending so highly

to learning, as our Author doth, and yet print himself a stranger to the progress thereof.

It is true indeed that M. Newtown hath discovered an inconvenience in Refractions, which was not formerly known, and that therefore Metallin Mirrours are more proper then glasses: but this hath not ad∣ded any thing to that universal rule I pre∣sently mentioned, which scientifically brin∣geth the sight to any degree of perfection, and holdeth in these Telescops, as well as in all others: yea, these Telescops were known before, only their advantage above others was not known.

What he saith of M. Hook, is most im∣proper: seeing there he only promiseth to accomplish or bring to practise what hitherto hath been attempted, or by all most desired; not at all mentioning the Science, which our Author questions.

Let any man consider the vast extent of that rule, and think what can be more large. I do not question that there may be many excellent and subtil inventions for promoting sight, as to practise: but I am sure the scientifick part cannot make the

sight infinitly perfect, and it hath alrea∣dy brought it to any degree of finit perfe∣ction.

He flatters himself that he hath gained the victory, as to the Hydrostaticks: but upon what account, may be seen in my Let∣ter; which being written in privat, only for disswading him from making himself ridiculous, and for curing him of his blind presumption, was framed to his capacity, and not for the learned world. And seing it was necessar, because of the importu∣nity of his Letters, to signifie to him, that this Science was already perfected, as to all these things whereof he is capable; it was more civily and respectfully spoken, to say, that the Hydrostaticks were already perfected, then to say, that they were fur∣ther perfected then he could reach.

Our Author should know that all mixed Mathematical Sciences, are nothing else but Geometrical Demonstrations, founded upon some Physical Experiment: So that Geome∣try, to speak properly, is the only Science in Mathematicks, and their only store∣house for rules, methods, reasons and in∣ventions: It is certainly defective in several

things; but these are far above our Authors conception.

He next strives to perswade the unlear∣ned, that he hath first taught Astronomers the use of Telescops and Pendulum clocks; but I leave this to the examination of his experiments. Yet I must not pass that which he desires the Reader to mark; to wit, my non-sense, in saying, That the invention of representing the Sun or Moons motion in a se∣cond of time, had been greater, if the eye had been away. And I intreat the Reader to mark as well, how M. Sinclars dulness ma∣keth him impute his own non-sense to me: for in his printed Letter Feb. 22. he chal∣lenged as a great neglect, that the Eye is not added in an expression of a former Let∣ter; as if any could have dreamed that the observation might be without the eye; to which I answered, That the invention had been greater, if the eye had been away: and surely so it had: Nor could this have escaped M. Sinclar, if he had not wanted his eyes; but his blindness hath made him stumble upon my expression: and because he could not bruise it with his fall, he hath lashed me for his own fault. Surely this discipline

is very near in kind to his doctrine, for they are both unreasonable.

I have nothing to say against his mira∣cles in the West, especially that grand one of the Sun seen in Winter for an hour about midnight, eight degrees above the Hori∣zon: except, that it is only mentioned in his Book; no man, I ever spoke to, having heard of it; altho I know many who have been in the place mentioned, and very in∣quisitive concerning it. Besides, that lay∣ing one aside, it far surpasseth all miracles of the heavenly bodies, recorded in facred History.

If our Author think that he was well exercised, when he was making his obser∣vations of the Comet, he should judge a part of his time well spent, in letting the world know for what they served: but he seems to intend no more; then to make men believe, that he is not ignorant of a degree or a minut, altho he reckons the Suns mo∣tion by inches.

I question not, that a Coal-hewer is more useful to the Countrey then he and I both: and therefore he is obliged to me, for gi∣ving him a more useful trade, then he now

driveth. Nor can I deny, but he justly de∣served it; for a Coal-hewer is one who ma∣keth gain by digging in another mans mine; and so hath he done; for that Histo∣ry of Coal which he hath printed, is none of his, altho he hath made advantage by the publishing and sale thereof. But this is no great wonder, since the most part of the truths contained in his writings, are dig∣ged out of other mens works. And that the Author of this History may not escape the fate of others with whom he maketh so bold, he mixeth with his doctrine, some mistakes of his own, and particularly that erroneous application of Euclid above mentioned in page 4. of this Book.

Now my Lords and Gentle-men, who are Coal-masters, I pray you consider how un∣justly M. Sinclar inferrs, that I design for you no better name then I have given to him; and how maliciously he thereby en∣devours to creat in you a prejudice a∣gainst me. I highly esteem and honour all such whose knowledge and vertue maketh useful, and ornaments to their Countrey. But pardon me, that I suffer not M. Sinclar to usurp to himself the name of a Phi∣losopher

for writing this History, (altho it were his own) since he wants the Science of Coal; for it is not History, but Science, that makes the Philosopher.

I need not concern my self much in his censure of Des Cartes; for he is as far exal∣ted above my commendation, as he is with∣out the reach of M. Sinclars detracting tongue.

He may well say, that he is not afraid I shal come the length of his labours in Glasgow Colledge, about Ʋniversale, and Ens¦rationis; for in his last Logick Notes, he hath thirty sheets of paper upon Genus and Ob∣jectum Logicae, Ʋniversale and the Praedica∣bles; which falsifies the first sentence of the Epistle to the Reader of his Ars Magna.

He might have holden his peace of Rhe∣torical and Algebraical composition and reso∣lution; for he knows no more of either but the name. If he had read this part of my Letter right, he would have had some other fansies, then he here expresseth; as I should show, were not this too sheepish a subject to be insisted upon.

It is true that a Letter was sent to M. Sin∣clar, containing the words which he

printeth; but it is as true, that the same Letter contained the condition of that pro∣mise which he there mentioneth; to wit, If he made it appear that his Book were an∣swerable to his Edict. The concealing of this is so great a proof of his candour and ingenuity, that infallibly it will procure credit to any thing he affirms.

Now this Good Man having spent ma∣ny of his spirits in this tempestuous con∣flict, is opprest with drowsiness; and having fallen asleep, he dreams all the rest of his Postscript. For I am sure there is not one in this Ʋniversity, who ever either had his name in an Almanack, or craved any man pardon upon such an account.

I have seen the Pamphlet he speaks of with the Advertisement to the Reader, and found nothing in it of any ingenious Gentle∣man Artist, set upon inhumanely as by two Mastives; but some Printer checked for playing the Astronomer unhandsomly, and that under a borrowed name, for to make his Prognostication the more vendible; a practise too ordinar. Our Author here tal∣king of two, judgeth this business to be of the same difficulty with that of D. Mores

butter Scon, which could not be sufficiently fenced from the violence of the Air, by less then the Syllogistical force of two bold brethren.

However, if there be any errours in that Almanack, he bewrays his ignorance in passing them; while he lets a fling at the mistake of a Table, and at some Chronologi∣cal Rhymes, things of no importance. For the first, it may be imputed to a piece of rashness, occasioned perhaps by the obscu∣rity of that Tables explication, but not to ig∣norance; seeing such triffles, as Tobacco-box∣tables, and Pocket instruments, which pro∣duce nothing, but what can be better done without them, conduce not to knowledge: And therefore no reproach for a man to be ignorant of them, being contrived only for Mechanicks, and such sensible Demon∣strators as my Adversary is. As for the Rhymes, I suppose there is as little necessity of thinking the Author of them, and of the Almanack, to be the same, as of judging the new and unheard-of Hydrostatical Theo∣rems, and the bundle of Latin Sentences in the reply to my Letter, to have been tursed by the same hand▪

I have no regard for Rhymes, and yet for recreation, I must take notice of our Au∣thors two Criticisms; whereof one is, the two last lines exceed the former in a foot, con∣trare to that of Horace,

Primum ne medio, &c.

Consult our English Poëts, Sir, what weight this authority hath with them. The other is: It should not have been said, Since that of nought the Lord created man. But, Since that of dust, &c. Pray you, Sir, is this sound Philosophy; and if it be, how taught you your Scholars, Cap. 7. de Causalitatib. Caus. Prim. Creatio est actio causae primae, quâ¦res primo ex nihilo producuntur? But who then can this Prognosticor be? It is very proba∣ble, from the rable of Astrology, (for there is none of that profession among us) that he is my Antagonists Apocalyptical Astro∣logue, who Lib. 6. Dial. Phys. 3. Sect. 1. be∣sides his Astrological Predictions, and Pro∣phesies out of the Old Testament, did from the Revelation of S. John, with great zeal declare many, and these even wonderful things, concerning the number of the Beast 666. and the Alphabetical letters A. B. I. S. of great affinity with it. The mystery of

these must not be revealed, lest it occasion the discovery of that divine Astrologue.

There is little heat here about Ens ratio∣nis; that crack-brain'd knave hath evani∣shed, together with his Cousin-germain M. Sinclars dearly beloved Forma sub∣stantialis materialis. For ought I know, they have got in to his Nihil spatiale, to erect a Colledge of Fanatick Philosophers.

I Am now to examine his Epistle to the Reader, where he complaineth excee∣dingly of Envy, because the Masters of this Ʋniversity would not take his word for the novelty of his inventions: Neverthe∣less he must grant (if he will be ingenuous) that they have done him a courtesie, in cau∣sing him prefix a more modest Title to his Book, then his Edict carryes.

He wrongs M. Boyl egregiously, in cau∣sing him say generally, that Archimedes's Demonstrations have more of Geometrical subtility then usefulness; whereas he saith only (in the Preface to his Hydrostatical Paradoxes) that many of his Hydrostatical Propositions have more of Geometrical sub∣tility then usefulness. It were non-sense to

speak so of Demonstrations, seeing their only use is to prove the thing in question: which if they do, they cannot be called useless; and if they do it not, they cannot be called Demonstrations.

Our Author now compares his method with that of Archimedes's forsooth. He is more speculative, our Author is more pra∣ctical. So may a Trone-lord say: Archi∣medes was more speculative in his Staticks, and he more practical. Next Archimedes's Demonstrations are Geometrical, and his Phy∣sical. That is to say, Archimedes's reasons are sure and solid, and his are conjectures: And then Archimedes's Demonstrations are but for the use of a few, and these for the use of all. He might truly have added, And for all uses, except to convince; which is the proper use of a Demonstration. As for his last comparison, Archimedes was more wise then to illustrat that in his Book, which any mean man might do, and was already demonstrated. But our Author needs not imagine, that a rational man will venture any surprising Demonstration to the world, without practising it, if he can: yet there was no necessity that he should

swel his Book with it. I say the like of Stevinus, in whose Demonstrations, I am not afraid our Philosopher show any defect, ne∣vertheless that he be pleased to speak at random.

He beginneth now to tell the strange things he hath invented. And first, he saith, that he considereth the pressure of the wa∣ter with the pressure of the air joyntly. Can our Author be so ignorant, that he knows not the arise of the Toricellian expe∣riment? Was it not from the considera∣tion of Pumps and other Hydrostatical ma∣chines, that they had no effect above 33. or 34. foot? Was it not considered here by Galilaeus, that water pressed water no fur∣ther then its own level; and it was proba∣ble, the weight of the Air might press it up the rest of the way (seeing it was not much) which it ascended in the Pump? Upon this account, he projected the expe∣riment first in water, (where was conside∣red the pressure of Water and Air joyntly) and afterwards Toricellius perfected it in Quick-silver, judging rationally, that the great weight of the fluid by shortning the tube, would facilitat the experiment. In

M. Boyls continuation of Physico-Mechanical Experiments, Exper. 13. 14. 15. Doth he not consider the pressure of both together? Yea, is there any intelligent man who now speaks of a Pump, or any Hydrostatical en∣gine, without considering both these pres∣sures together?

All these counterposings, which he speaks of, have been tryed by M. Boyl, and also many more; to wit, oyl of Turpen∣tine, and oyl of Tartar, &c. but if our Au∣thor please, he may try it yet with Ale, Beer, Urine, &c. and all these shal be new Experiments. He should have been more general in these tryals, and more particu∣lar in the mysteries and secrets of the Art which he hath discovered, and none else can get notice of. Archimedes asserts the weights of all fluids in general, and conse∣quently of the Air, if it be a fluid, which the Learned never yet denyed: Yea, Ar∣chimedes's Cōmentator Rivaltus (who died long before the Toricellian experiment) mentioneth the Air and its weight.

That assertion of M. Boyl is true at present, and will constantly be so, suppose every man alive print such Volums as our

Author hath done. However, the learned Doctor Wallace hath published a Book not long ago, notwithstanding all our Authors invention; in which he deduceth more then ever our Author shal know of the Hy∣drostaticks, as consectaries from one pro∣position.

Now, Reader, I stay no longer here to consider my Adversaries indiscreet railings and provocations; for this were unworthy both of you and me: But that you may know, that I am a man of my word, I pro∣ceed to the survey of his works, as I promi∣sed in my Preface. And I am not a little in∣couraged to this, by the hope of gaining as many Guinies, as may help that pitiful poverty, wherewith he upbraideth me.

But lest he think that the Probleme which his Brother proposeth concerning the bringing up from the bottom of the Sea, any weight that can be sunk therein, hath bougled me, I think fit to give thee here three several answers thereto.

First then, for effectuating that which is there proposed, you shal take the new in∣vention, called, The Dyving Ark, one so large that it requires a greater weight to

sink it down, then the Pondera demersa: which being sunk down near to the Pon∣dera demersa, the Dyver must first bind them to the Dyving Ark, and then loose away the weight which did sink it: Now the Pondera demersa, being ex hypothesi, lighter then the weight which was suffi∣cient to keep the Ark at the bottom, must of necessity be pressed up with the Ark by the water: and the nearer it cometh to the brim, the motion will be the swifter, not only for the acceleration of the motion, but also because the Air dilateth it self, and (as I determinat in my Examination of this dyvink Ark) the Ark is pressed upward with as much force, as the quantity of wa∣ter equaling the included Air, would cause by its weight in the Air. But if the Inventer will take my word upon it, his Ark must be stronger then a Wine glass, and without holes in the bottom: nay, it must not have a Glass window of a foot in square, at least not near the bottom. And if the Pondera demersa be great, when he hath done his utmost, in case the bottom of the new Invention get out, you may have sup∣ply from the old Hydrostaticks: Thus,

You shal take at a low water, some great strong tuns banded with iron, so many of them, that being all full of water, they are heavier then the Pondera demersa in the wa∣ter; that is to say, that the weight of all these tuns full of water, may weigh more then the Pondera demersa, having rebated from their weight, the weight of their quantity of water. These tuns being all emptied and exactly closed, and iron chains or strong ropes tyed to their iron bands, let the Dyver go down in his Bell, and bind these chains or ropes (all the tuns may be fastened to one chain) to the Pondera de∣mersa, as near as may be; and the rising wa∣ter shal lift the Pondera demersa from the ground; which being once done, they are easily drawn any where. If the Pondera strike on the ground, at the next low wa∣ter stent the chains as much as ye can.

I suppose any man who tryeth these ways, will be best pleased with this, which hath been known these many ages: seeing it is far easier to multiply tuns, then to make a vast bulk of an Ark, with a bottom proportionably strong, to resist the pres∣sure of the water, and to be troubled with

a weight sufficient to demerge the same. These two Answers I have got from my two brethren the inferior Bedals, who are as fertil in affording satisfactory answers, as my Adversaries Brother is in starting subtil questions. If it be objected against the last of these two Methods, that it can only be practised where the sea ebbeth and flo∣weth, I give you a third.

Take two ships (any of which is suffi∣cient to raise the Pondera demersa) the one deep loadned with stones, or any such thing, the other altogether empty. Bind the loadned ship as near as may be to the Pondera demersa (which may be easily done by the help of the Dyving Bell) and then liver her into the other which was empty: This livered ship shal raise the Pondera de∣mersa from the ground, which afterwards may be easily drawn any where. And if perchance they strike on the ground in the drawing, let them be bound again to the new loadned vessel, doing as formerly. This method, I suppose, you will find in Vitruvius, who is a very old Writer; and yet if M. Sinclar had given it, it is like, he would have listed it amongst his new

Inventions, as he did Riccioli's erroneous argument against the motion of the Earth.

Hitherto I have been employed in parreing those thrusts which M. Sinclar gives in at me, through all the Postscript, & part of the Preface to his Hydrostaticks: It is now high time for me to prepare an assault for him, this being a part of my Province: and in forming it, I shal make use of no wea∣pon, but Reason: hoping from it, better suc∣cess, then my Adversary hath had; & the ra∣ther, because he is so great a stranger to it.

The first shal be upon his Hydrostaticks, because that began the debate. The second upon his Ars nova & magna, because of the reproaches my Masters have sustained for their just censure of it. And the last assault shal be upon his Tyrocinia, which indeed is more blameless then the rest, being freest from errours, and more consonant to its title; yet albeit it had no name prefixed, it could not but sufficiently discover the Tyro and the Great and New Artist, to be all one. All this shal be done in the proper language of each Book, that every work, & its exa∣mination, may be understood by the same Reader: And so I begin with the Hydrosta∣ticks.