Book VII. Mechanick Powers. 115wheel C; if now D on the top be made hollow, or E on theſide of che Caſe ſticking out, be put under the Waggon, orother weight, and the Wheels being turn d the Priſme al-cends, and going forth of the Caſe, forces the weight up-wards; and if the wheels are turned the contrary Way, che.weight deſcends likewiſe. ö

If to this Engin you add a leaver, one end whereof beingput under the hollowing D or E, and the other end of theleaver lean, or ſtay on the Earth , and that part of theleaver, next the earth, be put under the Waggon, or Otlierweight, and then turn the Wheels, it will make a compoundEngin much ſtronger, which you muſt note carefully, for in-deed many Engins by addition of the like leaver are much

helpt.

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Engin. II.

To raiſe a vaſt weight with an Engin compounded of aPulley, Axis in Peritrochio, and 4 perpetual

Screw .

Fig. 92. Mm che Cylinder C D, in the middle whereof

make 4 Or 5 Spires of a Screw , which whileche handle EF with the Cylinder is turn d about, the Spiresinfold themſelves with the teeth of the wheel B, and turn itabout: And while the wheel E. is turn'd roun'd, the ropeB G H, drawn about the pulleys G and H, is wound about itsAxis: By this means, we may with great eaſe raiſe any greatweight by the power P. I have cauſed the like Engin to be

made, by whoſe means, I did move a Milſtone with ſo little

reſiſtance, that with a ſmall Silken Thred, faſtned to the

handle P, and pull d by the hand, 1 have turn'd about theScrew , and taken it up, being the weight of 200 pounds,and not broke che thread. And if inſtead of the handle E E

ou fit a Wheel furniſnt With little boards, this being turn'dabout with the breath of the mouth, will raiſe che Mill-ſtone.

22 Engin