Gas meter

[ Gas, and Gr. metron, a measure.] An apparatus used for measuring the volume of gas. The term is usually restricted to an instrument used in measuring the illuminating gas supplied to consumers. The wet meter consists of a drum, divided into 4 chambers, and caused to revolve on an axis by the ingre and egre of the gas. This drum revolves in water, and its revolutions are communicated to a set of multiplying wheels on the face of the meter, by which the rate of consumption is noted. The dry meter consists of a ve el in which the gas is introduced into expansible chambers of definite volume, the alternate expansion and contraction of which are registered by clock-work. The dry meter has the advantage of not freezing in winter, and the gas in pa ing through it takes up no additional moisture to be condensed in the pipes.