A decorative rectangular woodcut headpiece featuring symmetrical foliage, floral motifs, and two small figures on the sides, flanking a central circular mask or emblem.

EXPLANATION OF THE

parts & usage of this

THEATER.

FIRST PROPOSITION.

Certain instruments invented by geometric and mechanical reason, the measurements and foundations of which are, for the most part, utilized by the following inventions in this work.

EXPLANATION OF THE 1st FIGURE.

A large decorative historiated woodcut initial 'E' depicting foliage and vine patterns, used to begin the word "EN" (In).
IN THIS first figure, the author presents to us the instruments most necessary in mechanics mechanique: the science of motion and tools, and which he often uses in the following machines: namely the compasses and the ruler, which are on the east side The author uses cardinal directions—East, West, North, South—to orient the reader to different parts of the printed illustration.: and he has made his compasses in such a way that, when needed, they can serve as a measure, a ruler, and a square, while nevertheless remaining compasses: and they must have a length (even if it is not observed here) of either one foot, or a half, or eight inches, or some other certain length which can be helpful when needed. Furthermore, in the middle, there is the screw and the nut, and toward the west the instruments with which they are made. And those in the middle must be carefully considered: for he employs them often in the following machines: where one must make use of the screw as in engines for lifting and pulling burdens, and its use is very profitable. For (as will be said hereafter) the screw never slips back Original: "iamais la vis ne retourne." This refers to the "self-locking" property of a screw, where the friction prevents the load from turning the screw backward.: and it has an incredible force, as daily use sufficiently shows. And this is all that should be considered regarding the first figure.

PROPOSITION II.

A new and singular instrument for measuring all the notable parts of any proposed body, in order to know the proportional relationship of these parts in its composition.

EXPLANATION OF THE 2nd FIGURE.

This instrument is very useful to those who wish to take the measurements of a body, in order afterward to make another entirely similar to it: inasmuch as it can constitute the two legs of a triangle, having such an angle and such proportion between them as shall be agreed upon. This can be well understood by the explanation of its parts, which are as follows. Firstly, there are two branches, of which the one shown on top, where a circle divided into 16 appears (which is the head of the nail), extends from the angle of the west and the south to the angle of the north and the east: and the other, which is entirely similar to it, except that it does not receive the head of the nail, pulls from south to north: both being divided into 15 parts, and each part being again divided into five: so that there are 75 parts in all: the said instrument being able, however, to be ma- The text ends mid-word, continuing on the following page.

mechanics, geometry, instruments, compasses, ruler, screw, nut, triangle, proportional ratio