*hydrometrical*

{ } a. [ Cf. F. hydromètrique. ] 1. Of or pertaining to an hydrometer, or to the determination of the specific gravity of fluids. [ 1913 Webster ]

2. Of or pertaining to measurement of the velocity, discharge, etc., of running water. [ 1913 Webster ]

3. Made by means of an hydrometer; as, hydrometric observations. [ 1913 Webster ]

Hydrometric pendulum, a species of hydrometer consisting of a hollow ball of ivory or metal suspended by a treated from the center of a graduated quadrant, and held in a stream to measure the velocity of the water by the inclination given to the thread; a kind of current gauge. [ 1913 Webster ]