Book IV. Mechanic Povers. 89Corollary.

Hence it follows, that an immovable Pulley is a Leaver of thefirſt kind, of equal Armes, and a movable one is a Leaver orfthe ſecond kind, or in like manner of the third kind, of equalArmes.

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PRO P OCC. VIII.A Theorem.

to move he Vhpeels of a Dial, or Cloche for 1 2 Hourc,there be required à weight ef 5 0 pound, and theweight deſcend 20 feet, Leeping the ſame deſcent,a weight that ſhall move the Clock 24 Hours mall re-guire to be 100 pound.

T 35 propoſition which may eaſily be deduced by the Cerol-lar) of the precedent propoſition, becauſe of the com-monneſs of its uſe, may be propoſed in this manner; ſuppoſe acommon Clock that requires a weight of 50 pounds to keep itin motion, and ſuppoſe the place where the weight deſcends tobe 20 foot only, and this deſcent ſerves for 12 hours; and wewould, keeping the ſame deſcent, have a weight to ſerve for24 hours, I deſire the magnitude of the weight; I ſay, theweight required muſt be ro pounds.

The Demon. Suppoſe the motion of the Clock and its reſiſtance,to be after the manner of the motion of the other weight, tiscertain by the ſuppoſition that the reſiſtance of the Clock for 12hours, is leſs than of a weight of 50 pounds being movable20 feet; but the motion of the Clock for 24 hours is doubie fthat which is made in 12 hours, and in like manner a weightof roo pounds as movable 20 feet, is double of a weight of30 pounds that moves the ſame ſpace, therefore the motion ofthe Clock for 24 hours will be leſs than a weight of 100 poundsmoving 20 feet, and will be exceeded by the ſame cxceſßs.

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