Theatre of Instruments and Machines

Declaration of the 40th figure.

Certainly, I think the knowledge of this machine would bring no small pleasure, since its use often occurs and the skill of the artist fails; but by this means, the burden is lifted and drawn just as a ship is carried by water without any detriment to it; but those things desire a fuller declaration, which I shall describe in few words as it is easy for me. Here our author, for the sake of example, has seen to the painting of an obelisk, which is verging from the east to the west, distant from the northern line 2 measures and 6 palm-widths, and 2 measures and 10 palm-widths high. That [obelisk] is lifted by these instruments: To the north are two frames of timbers erected perpendicularly and fixed, with cords, as well as the gravity of their own weight, distant between themselves by this length, so that between them can be introduced the arms (verging from the angle of the north and west to the angle of the west and south, the length of which is 3 measures and 24 palm-widths), from the western end of which arms the obelisk hangs, while the other part of the same is on the ground: those arms, however, are drawn by those ropes tied to them, and the crane in the middle (in which is the triple-pulley) is assembled; there is, however, a winch in the part of the northern frame distant 13 palm-widths from the eastern line. Again, there is a machine forming a scalene triangle by which the obelisk is sustained; on the side of this triangle subtended are ropes which are seized by hooks appearing from the obelisk. Likewise, the obelisk is lifted by a counterweight verging toward the south (parallel almost to the eastern line), the length of which is 12 measures and 16 palm-widths, and in its extreme southern part are weights, and the crane standing in the middle compels that weight: the upper ropes, however, are produced from the winches in which are the triple-pulleys, which ropes draw the obelisk toward the south. These winches, however, must sit as high as the part of the obelisk to which those ropes are tied. Now, after the arms of which we spoke have reached the northern winch, it must be begun anew, so that the obelisk may be carried again. This is the proposition.

PROP. XLI.

A new and certain instrument for constructing chimneys, even in a low place, from which both the rays of the sun and the blowing of winds are warded off in such a way that no one in the chambers is offended by smoke.

Declaration of the 41st figure.

No one does not know how great the utility of this thing is and how much is required for the comfort of a habitation; but I will declare this as much as I can by conjecture, experience, and reason, since from the figure described obscurely by the author himself, everything cannot be clearly perceived: it is a building in which the chimney is exposed directly to the sun in this figure, in which chimney appear many slits like the legs of a triangle, to which are opposed similar ones from the opposite side, not so that they correspond, but so that a slit is opposed to a full wall, so that as the wind enters through one, the smoke may exit through the opposite and lower one. The top opening of the chimney must be fashioned so that a rim is placed around it, lest the chimney be filled with the rays of the sun. With these things thus established, the proposition appears.

PROP. XLII.

A new type of reading-desk, in which the form of letters, reflected and magnified by two opposing and fitted mirrors, renders the reading from the other [desk] more expeditious, and the sharpness of the eyes is less dulled.

Declaration of the 42nd figure.

This type of reading-desk does not lack subtlety, for its principle is situated in the reflection of rays from mirror to mirror.
This form of the reading-desk which is in the north is complete and finished in its parts, of which the rest are parts: its foot or fulcrum verges toward the south, then the support for books is in the middle toward the east, and it is bipartite, for in the upper part the book is placed, in the lower the mirror; in the base of the support appear two holes into which are placed the fulcra carrying the other mirror and the one above the former. The figure of these fulcra and the mirror, however, is toward the east. Now, with that turned to the book, the rays are reflected into the other, in which it is easily read. And this is easy and certain by experiment.

PROP. XLIII.

A recent invention, not to be scorned, by which water from very deep wells, without tubes and air-holes, can be drained by one or another pulley, so that the one who works the yoke perceives only half of the weight.