ogress, in contradistinction to one operated by the positive action of a part of the machinery.
A machine whose motivepower is concealed within itself, or, as the term is more generally understood, a machine which imitates the actions of men or animals, and, being moved by clock-work or other similar instrumentality, appears to perform certain acts by its own volition.
Among the most remarkable of antiquity were the automatons of Hero of Alexandria, who flourished about 217 B. C. They were made to move, as if alive, by machinery under the floor, and to utter sounds by the action of air driven by water through small pipes, or by means of air rarefied by heat.
His works are extant in Greek, and have been frequently translated.
They contain many curious anticipations of modern devices, as well as many curious tricks and effects no doubt intended as a part of the machinery of the priests to amuse the speculative and astound the ignorant.
Archytis's flying dove was m