Source : Webster's Revised Unabridged Dictionary (1913)

Hydrometry \Hy*drom"e*try\, n. [Cf. F. hydrom[`e]trique.]
   1. The art of determining the specific gravity of liquids,
      and thence the strength of spirituous liquors, saline
      solutions, etc.

   2. The art or operation of measuring the velocity or
      discharge of running water, as in rivers, etc.

Source : WordNet®

hydrometry
     n : the measurement of specific gravity [syn: {gravimetry}]