Balance (derived through the Fr. from the Late Lat. bilantia, an apparatus for weighing, from bi, two, and lanx, a dish or scale), a term originally used for the ordinary beam balance or weighing machine with two scale pans, but extended to include (with or without adjectival qualification) other apparatus for measuring and comparing weights and forces. In addition to beam and spring balances (see Weighing Machines), apparatus termed "torsion balances," in which forces are measured or compared by their twisting moment on a wire, are used, especially in gravitational, electrostatic and magnetic experiments (see Gravitation and Electrometer). The term also connotes the idea of equality or equalization; e.g. in the following expressions: "balance," in bookkeeping, the amount which equalizes the debit and credit accounts; "balance wheel," in horology, a device for equalizing the relaxing of a watch or clock spring (see Clock); the "balancing of engines," the art of minimizing the total vibrations of engines when running, and consisting generally in the introduction of masses which induce vibrations opposed to the vibrations of the essential parts of the engine.