(Machina), in the general, signifies any thing 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 μηχανη, "machine, invention, art." And hence, in strictness, a machine is something that confers 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 ingenieurs or engineers.

Machines are either simple or compound. The simple 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. Κλίμακις, or scaling ladders; 2. The battering ram; 3. The helepolis; 4. The χερσον or tortoise, called by the Romans teftudo; 5. The στρογγυλος or egger, which was faced with stone, and raised higher than the wall; 6. Upon the στρογγυλοι were built πυγγαι or towers of wood; 7. Περγα, or other hurdles; 8. Cata- pulche, or καταπολικαι, from which they threw arrows with amazing force; and, 9. The λαβελαι, περισσοι, or αριστα, 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 balilla, the catapultia, and the scorpiion.