\Hy*grom"e*ter\, n. [Gr. ? wet, moist + -meter: cf.
F. hygrom[`e]tre.] (Physics)
An instrument for measuring the degree of moisture of the
atmosphere.
{Daniell's hygrometer}, a form of hygrometer consisting of a
   bent glass tube terminating in two bulbs, the one covered
   with muslin, the other of black glass, and containing
   ether and a thermometer. Ether being poured on the muslin,
   the black ball, cooled by the evaporation of the ether
   within, is soon covered with dew; at this moment, the
   inclosed thermometer gives the dew-point, and this,
   compared with the reading of one in the air, determines
   the humidity.