(Machina), in the general, signifies anything that serves to augment or to regulate moving powers: Or it is any body defined to produce motion, so as to save either time or force. The word comes from the Greek μηχανή, "machine, invention, art:" And hence, in strictness, a machine is something that consists more in art and invention, than in the strength and solidity of the materials; for which reason it is that inventors of machines are called ingénieurs or engineers.

Machines are either simple or compound. The simplest ones are the seven mechanical powers, viz. lever, balance, pulley, axis and wheel, wedge, screw, and inclined plane. See Mechanics.

From these the compound ones are formed by various combinations, and serve for different purposes. See Mechanics; also Agriculture, Cannon, Centrifugal, Steam, Furnace, Burroughs, Ramsden, &c. &c.

Machines used in war amongst the Greeks were principally these; 1. Κλίμαξ, on scaling ladders; 2. The battering ram; 3. The heliopolis; 4. The ξύλον or tortoise, called by the Romans teftudo; 5. The σχοινος or agger, which was faced with stone, and raised higher than the wall; 6. Upon the σχοινος were built πύργοι or towers of wood; 7. Γέραξ, or other hurdles; 8. Cata-putia, or καταπυλία, from which they threw arrows with amazing force; and, 9. The λοβόνειον, περικάλα, or αφίγια, from which stones were cast with great velocity.

The principal warlike machines made use of by the Romans were, the ram, the lupus or wolf, the teftudo or tortoise, the balista, the catapultia, and the scorpion.