The text describes detailed instructions for assembling parts of a machine used in art or technical drawing. It involves the arrangement and attachment of boards, a box, and a mirror with specific measurements and positioning to ensure functionality. The components include sliding boards, a cylinder with a screw, and a strategically placed mirror, outlining specific angles and setups.
METHOD TO LEARN
8. Above the machine is a board approximately fifteen inches long and nine inches wide, with a notch called PMOQ, about nine or ten inches long and four inches wide. On this board are attached two rulers shaped like a dovetail, between which another board of the same length as the first, and about six inches wide, slides. This second board is pierced in the middle, and within this opening, which should be about three inches in diameter, a nut is added for raising and lowering a cylinder on which there is a screw, and whose height is about four inches. It is in this cylinder, as will be seen later, that the convex glass is placed.
A box, marked X, slides above the previously mentioned board (No. 8), shaped like a small square tower, roughly 7 or 8 inches wide, and 10 inches high. The side B, which serves as a door, is turned towards the front of the machine. The back of this box has at its base a square opening N, of about four inches, which can be closed by a small board I that slides between these two rulers.
10. Above this square opening, there is a slit parallel to the horizon, covering the entire width of the box. Through this slit, a small mirror is inserted into the box, which slides between two rulers on either side, placed in such a way that the mirror's glass, turned towards the door B, forms an angle of one hundred and twelve and a half degrees with the horizon.
11. This mirror, in the middle of the side remaining outside the box, has a small iron plate serving as a base for a small screw, which advances and helps to fix the mirror in place, as seen in H. To fix it like this,