(Machine), in the general, signifies any thing that serves to augment or to regulate moving powers: Or it is any body destined 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 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. Κλίμακες, or scaling ladders; 2. The battering ram; 3. The ἑλέστρος; 4. The σκάβων or tortoise, called by the Romans testudo; 5. The σκάβων or agger, which was faced with stone, and raised higher than the wall; 6. Upon the σκάβων were built πυργοί or towers of wood; 7. Γέφυραι, or osier hurdles; 8. Cata-pultæ, or καταπληκται, from which they threw arrows with amazing force; and, 9. The λιθόβολαι, πτεροβολαι, or αἰχμαλοτοξα, 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 testudo or tortoise, the balista, the catapulta, and the scorpion.