A general collection of discourses of the virtuosi of France, upon questions of all sorts of philosophy, and other natural knowledg made in the assembly of the Beaux Esprits at Paris, by the most ingenious persons of that nation / render'd into English by G. Havers, Gent.

II. Of Perpetual Motion.

At the Second Hour it was said, That the Perpetual Motion to which this Hour was design'd, is not meant of Motion to Sub∣stance, which is Generation and Corruption, by reason of which Compounded Bodies are in Perpetual Motion; For in Corrupti∣ble Things, every Moment is a degree of Corruption. Nor is it

meant of Motion to Quantity, which is Augmentation and Di∣minution; nor of that which is made to Quality, which is Altera∣tion, but of Local Motion. And again, the Inquiry is not about the possibility of Local Motion in Animals, nor about running-water, or Fire, to whom it is natural; as appears in Mills which are upon Rivers, and Turn-spits, or Engines, which the Smoke causeth to turn about. Wherefore his Invention who exactly fastned a Girdle to his skin, which rising and falling as he took his breath, serv'd for a perpetual spring to a Watch that hung at it, (which by that means needed not winding up) was not the Perpetual Motion which we mean. No more was that which proceeded from the wings of a little Wind-mill, plac'd at the mouth of a Cave, which the Vapour continually issuing forth, caus'd alwayes to move. But it must be in a subject natu∣rally unmoveable, made by Art to continue its Motion: And this is prov'd possible, I. Because, as Hermes saith, That which is below is as that which is above;* 1.1 Now we see above the Perpetual Motion of the Heavenly Bodies, by example of which it is cer∣tain that this Motion must be Circular. In the Second place, Nature hath not given us a desire of Things impossible. Now, an infinite number of good wits shew by their search the desire which they have of it. Thirdly, it is held that Archimedes had it, whence it was feign'd that Jupiter was jealous of him. In the Fourth place, it seems that if a very uniform Circle could be put ex∣actly upon a Pivot or Spindle, and were set in Motion, it would never stop any more then the Heavens, because it doth not poise or gravitate upon its Centre, so long as it is turning, (as it appears by a Stone, which poiseth not in the Circle made on high in turning it round) and so nothing resisting the external Agent, the Motion must last as long as the impression lasteth; and the impression must last alwayes, because nothing resists it; but on the contrary, the Agitation continues it. Thus of all the Models of Engines, contriv'd to move perpetually, we see not one that makes so much as one turn; Whereas a plain wheel makes above a thousand, though it be not exactly plac'd upon its Centre, and the Poles be not two simple points as they ought to be, if that Art could come to perfection; in which Case the effect of Perpetual Motion would follow.

The Second said, That he held it for impossible, for that it is repugnant, not onely as to the Efficient Cause, which being limited and finite cannot produce an infinite Effect; but also as to the very form of that Motion, which must be either Direct, Circular, or Mixt. If it be Direct, it will be made from one term to another, in the one of which its Motion ending, it cannot be perpetual. And because the most certain Principle of this Direct Motion cometh from Gravity, which tendeth from high down∣wards; when it shall be arriv'd there, nothing will be able to mount it up again, Gravity having found its Centre and place; or if the Motion be violent, the impression being ended, it can∣not

re-produce it self of its own accord in the Engine; (other∣wise, it would be animated) and therefore it will cease from Motion. If the Motion be Circular, (as in this effect it would be the most proper in imitation of that of the Heavens) this moving Circle shall be in all parts either of equal, or different weight. If it be equal throughout, it shall not turn at all of it self, one part having no advantage over another; If it be unequal, and there be put (for example) four pound to raise up three, it will happen that when the greatest weight hath gotten the lowest place, the lighter parts will not be able to raise up the heavier; and so the Motion will have an End. Now if the Direct and Circular Moti∣on are incapable of this perpetuity, the mixt or compounded of both shall be so too. So that it seemeth impossible, by reason of the gravity of the matter (not to mention its corruptibility) to compose a Machine or Engine that moves alwayes. And were there any ground to think of it, some have conceiv'd it might be done with the Load-stone, which hath a Virtue of attracting to it self on one side, and driving away on the other, and so by continuing this little Motion (which would be of no great bene∣fit) it might render the same perpetual. But you ordinarily see that they who make these inquiries, onely find rest in their En∣gines and Motion in their brains, whereas they hop'd the contrary.

The Third said, That it appears by that which they call the Roman Balance, that the same weight hang'd neer the Centre, weighes less then when it is more distant from it. Consequently that disposing the weights which shall be round a wheel, so as to be neer the Centre about one half thereof, and distant from it the other half, you shall have a Perpetual Motion, which ought not to be accounted the less such, though the Matter should last but a year, yea but a day; it sufficing for a night to that name, that it lasts as long as its Matter; as 'tis seen in the Vice of Archi∣medes, termed without End, though it be made but of wood; not by reason of its lasting, but because the Vice being apply'd upon an indented wheel, instead of entring into a screw, there is no raising or letting it down, as is practis'd in those of Presses.

He prov'd it further, For that it is seen that by the help of that Vice without End, by the instrument term'd Polyspaston, and others of the like Nature, a Child may easily lift up a weight of 10000 pounds; Yea, even to Infinity, could the strength of the Cordage and the Instruments bear it. For it follows that if a less weight can lift up a greater, this greater will lift up a less; which will be the Perpetual Motion which we inquire after.

The Fourth reply'd, That this Motion seemed to him impos∣sible to find, not for its being unprofitable (for it would be one of the greatest helps that Art could afford Man, to ease him in his labours) but because there is in all Arts some thing of impos∣sibility; as the Quadrature of the Circle in Geometry, in Rheto∣rick the perfect Orator, the Philosophers Stone in Chymistry,

the Common-wealth of Plato in Polity, and in the Mechanicks Perpetual Motion. And whereas it is said that a less weight or less strength can lift up a greater, this is to be understood in more time: So that what is gotten in strength is lost in time; which comes all to one. For Example, one Man, or one hundred weight, shall raise as high in one hour, as much weight as four Men or 400. weights shall raise in a quarter of an hour by any Mechan∣ick Invention whatsoever.

The Last Hour was imployed in the mentioning of some En∣gines which had some likelihood of moving themselves endlesly; And amongst others, it was propos'd, That a Wind-mill ha∣ving a large wing, which the wind should alwayes drive behind, as it doth weather-cocks, and by that means alwayes present its four ordinary sails to the wind, might lift up so weighty a burthen whilst the wind blows, that the same burden coming to descend while the wind ceaseth, would cause a Motion of Con∣tinual Duration. Which also may be more easily practis'd in a Perpetual Fountain, by help of a Great Reservor which should be fill'd by help of the wind, and be emptying it self all the time that it bloweth not.

One Demanded, Whence it cometh that some are inclin'd to Mechanicks, others onely to Contemplation and Literature. It was answer'd, that this proceeds from the Resemblance which their Mind hath with the Things which they affect. The time being past for this Conference, this Question afforded the Sub∣ject to the next, for the first point concerning Resemblance, and chiefly that of kinred one to another; And for the Second, Whe∣ther Letters ought to be joyn'd with Armes.

Notes

• * 1.1

  Id quod in∣serius est si∣cut illud quod est superius.