From The Collaborative International Dictionary of English v.0.48 [gcide]:
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.
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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]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
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.
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2. A telescope. "Glazed optic tube." --Milton.
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3. A vessel in animal bodies or plants, which conveys a fluid
or other substance.
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4. (Bot.) The narrow, hollow part of a gamopetalous corolla.
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5. (Gun.) A priming tube, or friction primer. See under
Priming, and Friction.
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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.
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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.
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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.
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