Current Meter
an instrument for measuring the rate of flow of water 1 CURRIE in streams, canals, or rivers. The velocity of a stream is usually measured to determine the amount of flow. The modern current meter, which is an evolution of the type introduced in 1790 by Woltmann, a German hydraulic engineer, consists essentially of a vertical metal rod, weighted at the bottom. A tail is fastened to this rod, which keeps the apparatus in the proper position. Attached to the rod, and at right angles to it is a device consisting of a wheel with cupped vanes, and a rudder which keeps the wheel facing the current. This wheel is connected with a device which records its revolutions. From a known relation between the number of revolutions in a given time and the speed of the water, the rate of flow of any stream can be determined. The instrument is calibrated by drawing it at various known speeds through still water.