tube sheet

Flue \Flue\ (fl[=u]), n. [Cf. OF. flue a flowing, fr. fluer to
   flow, fr. L. fluere (cf. {Fluent}); a perh. a corruption of
   E. flute.]
   1. An inclosed passage way for establishing and directing a
      current of air, gases, etc.; an air passage; esp.:
      (a) A compartment or division of a chimney for conveying
          flame and smoke to the outer air.
      (b) A passage way for conducting a current of fresh, foul,
          or heated air from one place to another.
      (c) (Steam Boiler) A pipe or passage for conveying flame
          and hot gases through surrounding water in a boiler;
          -- distinguished from a tube which holds water and is
          surrounded by fire. Small flues are called {fire
          tubes} or simply tubes.
          [1913 Webster]

   2. In an organ flue pipe, the opening between the lower lip
      and the languet.
      [Webster 1913 Suppl.]

   {Flue boiler}. See under {Boiler}.

   {Flue bridge}, the separating low wall between the flues and
      the laboratory of a reverberatory furnace.

   {Flue plate} (Steam Boiler), a plate to which the ends of the
      flues are fastened; -- called also {flue sheet}, {tube
      sheet}, and {tube plate}.

   {Flue surface} (Steam Boiler), the aggregate surface of flues
      exposed to flame or the hot gases.
      [1913 Webster]
    

Tube \Tube\, n. [L. tubus; akin to tuba a trumpet: cf F. tube.]
   1. A hollow cylinder, of any material, used for the
      conveyance of fluids, and for various other purposes; a
      pipe.
      [1913 Webster]

   2. A telescope. "Glazed optic tube." --Milton.
      [1913 Webster]

   3. A vessel in animal bodies or plants, which conveys a fluid
      or other substance.
      [1913 Webster]

   4. (Bot.) The narrow, hollow part of a gamopetalous corolla.
      [1913 Webster]

   5. (Gun.) A priming tube, or friction primer. See under
      {Priming}, and {Friction}.
      [1913 Webster]

   6. (Steam Boilers) A small pipe forming part of the boiler,
      containing water and surrounded by flame or hot gases, or
      else surrounded by water and forming a flue for the gases
      to pass through.
      [1913 Webster]

   7. (Zool.)
      (a) A more or less cylindrical, and often spiral, case
          secreted or constructed by many annelids, crustaceans,
          insects, and other animals, for protection or
          concealment. See Illust. of {Tubeworm}.
      (b) One of the siphons of a bivalve mollusk.
          [1913 Webster]

   8. (Elec. Railways) A tunnel for a tube railway; also
      (Colloq.), a tube railway; a subway. [Chiefly Eng.]

   Note: In the New York area, the subways running under the
         Hudson River are sometimes referred to as the tube.
         [Webster 1913 Suppl. +PJC]

   {Capillary tube}, a tube of very fine bore. See {Capillary}.
      

   {Fire tube} (Steam Boilers), a tube which forms a flue.

   {Tube coral}. (Zool.) Same as {Tubipore}.

   {Tube foot} (Zool.), one of the ambulacral suckers of an
      echinoderm.

   {Tube plate}, or {Tube sheet} (Steam Boilers), a flue plate.
      See under {Flue}.

   {Tube pouch} (Mil.), a pouch containing priming tubes.

   {Tube spinner} (Zool.), any one of various species of spiders
      that construct tubelike webs. They belong to {Tegenaria},
      {Agelena}, and allied genera.

   {Water tube} (Steam Boilers), a tube containing water and
      surrounded by flame or hot gases.
      [1913 Webster]