Discourse on Mechanics.

the soldiers can climb onto the walls, all manner of shields, battering rams, mountings for arrows, everything of different types and names, and whatever else is necessary for war, which it teaches how to construct artfully and ingeniously.

However, this contains within it yet another science, which the Greeks call Βελοποιητικήν belopoietike/artillery-making, that is, Telifactionem the making of long-range weapons, or Usurpationem the usage of such weapons, in which the measure, division, preparation, and use of these arrows is particularly instructed.

There is also another science by means of which water is brought up from the depths against the course of nature, which is performed by scooping-wheels so that the water flows away more easily. Some call this Μηχανοποιητικήν mechanopoietike/machine-making, others, however, Ὑδραυλικήν hydraulike/hydraulics. The property of these machines, however, consists in the fact that they force certain pipes to discharge through the movement of the water and the pressure of the air, and give them the capacity to draw other water into themselves. Beyond this, they can serve for certain clocks, so that they are almost to be counted among Gnomonica the art of dialling/sundials, insofar as a division of hours and times is made by such machines. To these are yet to be added what the Greeks call Ὀχήμενα ochemena/floating objects, floating-works or ship-works; for that which floats on water gives rise to many kinds of machines.

Another part of the machines is Ἀυτοματοποιητική automatopoietike/automaton-making, or also Θαυμασοποιητική thaumasopoietike/wonder-making, that is, the art of self-acting calculation, which is performed by springs and an elastic force, by tensioned strings, screws, or weights, and other things besides.

The art consists of many different instruments and is therefore with all right called an art, and is worthy of being admired upon its consideration. Indeed, all mechanical rules and laws are required for it because of the particular effects occurring therein.

And since Pnevmatica the study of air and vacuums has been practiced most by the ancient philosophers and mechanics, I cannot pass it by here either, especially since this is one of the most prominent among the mechanical sciences and is closely connected with that which deals with water clocks. For through the mixing of three or even all four elements, much arises that can serve either for the most necessary utility of humans or also merely for special admiration.

Finally, there remains something to be mentioned regarding Dioptrica the study of light refraction/optics and Sphæropoëtica the construction of celestial spheres, both of which have a close relationship with each other and a wide-ranging utility, insofar as we use them for measuring the heavens and the earth. For, to speak first of Dioptrica, we use it very often in common life when, for example, we desire to know certain lengths, heights, or any distance. As in the art of fortification: the heights of walls, the depths of ditches, the widths of rivers. All this is found exactly with its assistance. One is also in need of it for water conduits; not to mention that it contributes most to the exploration of celestial phenomena. The like is also performed by Sphæropoëtica, which remains to be considered. It is a mechanical science that teaches how to manufacture such instruments through which we can investigate the movement of celestial bodies, which occurs either through a constant uniform movement of water, or through weights, or through other suitable instruments, many of which can be found manufactured by the ancients, no fewer by our ancestors, but most in our own times.