The Pneumatics of Hero of Alexandria

that they are, by their particular property, difficult, they have been made so easy that they could be understood by dull intellects. For by transporting them from one idiom to another, one does nothing more, or little more, than free them from those accidental shadows of a foreign language; and by commenting on them, one removes in part, but not entirely, the difficulty that proceeded from the subtlety of the subject. Now let us come to our intent: Aristotle wrote in the beginning of the Mechanical Problems original: "Quaestiones Mechanicae" that when it is necessary to perform any thing outside the order and disposition of nature, the difficulty that presents itself in doing so renders the mind hesitant, and to overcome it, the help of art is necessary. Now, that portion of art that aids in such difficulty we call Mechanics; and the craftsman who exercises it, a Mechanic; and the work he makes, a Machine. This is then divided, according to Hero the Mechanic, and as Pappus reports in the beginning of the eighth book, into two parts: that is, into Rational Mechanics (so to speak) and Manual Mechanics. The rational takes its foundations from Geometry, Arithmetic, Astronomy, and natural reasons. The manual makes use of the craft arts: metalworking, building, painting, and other similar ones. Parts of this are: Manganaria the art of building engines to lift or move heavy weights, which teaches how to lift weights, even if immense, with little force; Mecanopoetica the art of mechanical construction, specifically for hydraulics, which teaches how to easily raise water from deep places; Organopoetica the art of building instruments/machines, which teaches how to fabricate the instruments and all the machines called by the Greeks Poliorcetics siege engines, which serve for the use of war, and of which the books of Athenaeus, Biton, Hero the Mechanic, Pappus, Philo, and Apollodorus are full. The Centrobarica the study of centers of gravity, from which then depends the Sphaeropoeia the construction of spheres/models of the heavens, with its other companions. Finally, part of this is Thaumaturgica the art of wonder-working through mechanical devices, of which our Author made a particular profession, and it is divided into three other parts. Of these, one teaches us the various marvelous operations that are done by way of Clepsydrae water clocks, or let us say, of water passing minute by minute, and artfully, from one vessel to another; and of this, Hero wrote four books. The other teaches us, by way of wheels, springs, drums, nerves, and cords, to give motion to things by their nature immobile, and to make them appear animated; as one reads that they were