Hygrometer \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.
   [1913 Webster]

   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. Hygrometric