g, e, h t v d, a, r f c, Y, n, o, K, m, b S, p, x

g shall be the counterweight of the wheel m and, in the middle, of the wood b S. This counterweight g shall be only about one pound less than the weight of the two said things, so that the axle b feels no more than one pound of weight when it raises the wheel m and the beam b S.

If you set the diameters of the wheels in proportion together, it will be as if you had set their circumferences in proportion.

This is the final and true reckoning. o shall be 1/3 of an ounce thick; r will exceed this thickness of o by one eighteenth of an ounce. Hence when the spindle o gives 624 turns, the collector r gives 30 fewer, that is 594 — so that for every turn the collector makes, the thread twists 21 times. Now put it to the test by experiment.

If you wish to make this instrument small, for 4 women, make the wheel f n one braccio in diameter, the reel c a quarter [of a braccio], and the wheel e one braccio.

The wheel m is 4 and 2/3 braccia. The wheel n is 4 and 1/2 braccia. The wheel f is 4 braccia even. The wheel r is 1/2 braccio. The wheel e is 2 braccia and has 32 teeth. The reel c is 1/2 braccio and has 8 spindles. The thickness of the spindle's sheath is 1/4 of an ounce, that is 0. The axle h is one ounce thick and gives one whole turn. The little wheels t v are 2 ounces thick and have 8 spindles. The wheel a, which touches the reels, is 1/2 braccio and is half-toothed, with 8 teeth. When the handle Y gives one whole turn, the wheels n f give 4; the wheel r gives 32, and the spindle gives 864 — so that for every whole turn the collector gathers, the spindle makes 27 whole turns, as you will find by dividing 864 by 32. And every 8 turns the handle Y gives, the spindle rises more than 3 ounces. And for every ounce, the thread winds 85 and one third times. And if you want the windings closer together on the spindle, make it rise less than 3 ounces by thinning the axle h.

In effect, make it so that when the handle Y gives one turn, the wheels f and n give 4, and the spindle o, which is 1/3 ounce thick, gives 624. And the wheel r gives 30 turns fewer than o.

This is a way of spinning for 18 women, giving one braccio to each. It is done thus: turn the handle Y, and you will turn the reel or wheel e and the endless screw (worm) on the head of the wheel a. The wheel e turns, by means of the reel c, the two wheels f n. The wheel f gathers the thread onto the middle of the wheel r, and the wheel n twists the thread. And the endless screw turns the wheel a, which has 16 teeth on its edge and 8 on its face, being half-toothed [FIGURE], as you see. And when this screw has given 8 turns, the spindle fills from the top to its bottom; and giving another 8, the spindle fills again from the top down to the foot. And this happens because the axle h gathers the thread t b and raises the beam b S, which at p raises the wheel m on which all the spindles rest.