Aneroid \An"e*roid\, a. [Gr. 'a priv. + nhro`s wet, moist +
   -oid: cf. F. an['e]ro["i]de.]
   Containing no liquid; -- said of a kind of barometer.
   
[1913 Webster]


   {Aneroid barometer}, a barometer the action of which depends
      on the varying pressure of the atmosphere upon the elastic
      top of a metallic box (shaped like a watch) from which the
      air has been exhausted. An index shows the variation of
      pressure.
      
[1913 Webster]

Barometer \Ba*rom"e*ter\, n. [Gr. ba`ros weight + -meter: cf. F.
   barom[`e]tre.]
   An instrument for determining the weight or pressure of the
   atmosphere, and hence for judging of the probable changes of
   weather, or for ascertaining the height of any ascent.
   
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   Note: The barometer was invented by Torricelli at Florence
         about 1643. It is made in its simplest form by filling
         a graduated glass tube about 34 inches long with
         mercury and inverting it in a cup containing mercury.
         The column of mercury in the tube descends until
         balanced by the weight of the atmosphere, and its rise
         or fall under varying conditions is a measure of the
         change in the atmospheric pressure. At the sea level
         its ordinary height is about 30 inches (760
         millimeters). See {Sympiesometer}. --Nichol.
         
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   {Aneroid barometer}. See {Aneroid barometer}, under
      {Aneroid}.

   {Marine barometer}, a barometer with tube contracted at
      bottom to prevent rapid oscillations of the mercury, and
      suspended in gimbals from an arm or support on shipboard.
      

   {Mountain barometer}, a portable mercurial barometer with
      tripod support, and long scale, for measuring heights.

   {Siphon barometer}, a barometer having a tube bent like a
      hook with the longer leg closed at the top. The height of
      the mercury in the longer leg shows the pressure of the
      atmosphere.

   {Wheel barometer}, a barometer with recurved tube, and a
      float, from which a cord passes over a pulley and moves an
      index.
      
[1913 Webster]
 Barometric