Stēam'-gāuġe, n.

n. An instrument for indicating the pressure of the steam in a boiler.

☞ The mercurial steam gauge is a bent tube partially filled with mercury, one end of which is connected with the boiler, while the other is open to the air, so that the steam by its pressure raises the mercury in the straight limb of the tube to a height above the common level proportioned to that pressure. A more common form, especially for high-pressures, consists of a spring pressed upon by the steam, and connected with the pointer of a dial. The spring may be a flattened, bent tube, closed at one end, which the entering steam tends to straighten, or a corrugated vessel of elastic metal, or confined air.