Pivots that clothe one another, or rest, staying in one and the same socket, make those wheels of which they are the fastening perform various motions. / Universal pivot, in all the motions of the things joined to it, and it is very strong. / Pivot of 2 motions. / Pivot of more movements. / Pivot of two circular motions and two transverse, and one from top to bottom.

n, f, m

If you wished to make your pivot go always closed, so that it should never leap up, however much force were given it, you will make its socket, or 'mother', of mirror-metal, that is 3 parts copper and 7 of tin, cast together. And you will make this mother in two pieces, as is shown at m n, which enclose the pivot f between them. And they are locked with an iron wedge, and so the rest too will be of iron. In the half of the mother that stands above the pivot, one may put, on the lower part that touches the pivot, for the space of a finger's thickness, all lead, and the rest all of the said metal. And as it wears away, tighten it up with the wedge. The same may be done with the screw in place of the wedge, as is figured below.