GAUGING, the art of measuring the contents of casks or vessels of any form. Gauging forms a part of mensuration, but is frequently practised by persons unacquainted
with its theoretical principles, who work by certain rules, with the aid of a gauging-rod, and by the sliding rule. The ordinary gauging-rod consists of four rules made of box-wood, each a foot long, and united by brass joints, so that it may be folded together. See MENSURATION.
The term gauge or gage is applied in various ways, but always with reference to measure or proportion; or, in the literal sense of the word, to that which bounds or confines something else. Thus in physics it is applied to several instruments or apparatus for measuring the state of a phenomenon; such as the wind-gage, the rain-gage, the barometer-gage for measuring the degree of pressure of the air within the receiver of an air-pump, &c.; in architecture, to the length of a slate below the lap: in railway engineering, to the space between the rails; and the like.