Those wheels which are fixed in instruments, and which are turned by force or weight, will perform the office of a perfect balance when the one power is victor over the other.

8 — 4 4 — 8 / That spherical body which is suspended by opposite transverse ends will give of itself an equal weight to its supports.

8-44 / How all wheels are of the nature of a balance. / That wheel will perform the office of a perfect balance whose pole's centre is the centre of its circle.

16-8-8-4444 — windlass-rope (arganica) — 4 8 8 — 16 / Of the weight. / If you divide the weight you wish to raise with the tackle by the number of wheels that are in those tackles, and attach what results to the windlass-rope, you will find the weights that, as one descends against the other, will resist equally.

The cord that passes among the tackles has its two ends named in two ways: that part which gives cause to the motion and is fastened to the windlass is called the windlass-rope (arganica); and that which is fixed to the upper block, and lets the blocks neither run nor fall, is called the holding-rope (ritenente). / Of motion. The motion of the windlass-rope that moves the weight is longer than the motion of the weight moved by that rope through the tackles by as many times as is the number of wheels in those tackles. / Of time. By as much as is the number of wheels in the tackles, so much faster is the motion made by the windlass-rope than that made by the holding-rope. / Of weight. As great as is the number of wheels of the tackles, so much greater is the weight sustained than that which sustains. / Of motion. The number of braccia of rope gathered at the windlass exceeds those of the weight raised by it by as much as is the number of wheels in the tackles.