I say this: that if the man drawn below is set upon the levers in the manner of treadles, and has a pull at his belt and uses his head to thrust, and the lever on which he is placed has 2 parts of lever against one of counter-lever, know that this arrangement will make twelve hundred pounds of force with quickness, having half a braccio of movement.

The reason is that the man weighs 200 pounds.

The pull of the belt has its roller 1/8 thick and the lever half a braccio, which are 9/8 against 1/8; so that making with the hands a force of 25 pounds, it would make 9 times 25, which is 225.

The thrust above with the head makes a force of 200 pounds.

All these weights make a sum of 625 pounds; and the lever where he rests his feet is two parts against one, so that with the man standing with his feet at the head of the said lever together with the things named above, he will exert a force of 1,250 pounds, and it will be quick.

Let the feet rest here.

good

The force of which is spoken above. Arrange it so that when one cord of the roller winds on, the other unwinds.