Pneumatic action

Pneumatic \Pneu*mat"ic\, Pneumatical \Pneu*mat"ic*al\, a. [L.
   pneumaticus, Gr. ?, fr. ?, ?, wind, air, ? to blow, breathe;
   cf. OHG. fnehan: cf. F. pneumatique. Cf. {Pneumonia}.]
   1. Consisting of, or resembling, air; having the properties
      of an elastic fluid; gaseous; opposed to dense or solid.
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            The pneumatical substance being, in some bodies, the
            native spirit of the body.            --Bacon.
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   2. Of or pertaining to air, or to elastic fluids or their
      properties; pertaining to pneumatics; as, pneumatic
      experiments. "Pneumatical discoveries." --Stewart.
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   3. Moved or worked by pressure or flow of air; as, a
      pneumatic instrument; a pneumatic engine.
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   4. (Biol.) Fitted to contain air; Having cavities filled with
      air; as, pneumatic cells; pneumatic bones.
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   5. Adapted for containing compressed air; inflated with air;
      as, a pneumatic cushion; a pneumatic tire, a tire formed
      of an annular tube of flexible fabric, as India rubber,
      suitable for being inflated with air.
      [Webster 1913 Suppl.]

   {Pneumatic action}, or {Pneumatic lever} (Mus.), a
      contrivance for overcoming the resistance of the keys and
      other movable parts in an organ, by causing compressed air
      from the wind chest to move them.

   {Pneumatic dispatch}, a system of tubes, leading to various
      points, through which letters, packages, etc., are sent,
      by the flow and pressure of air.

   {Pneumatic elevator}, a hoisting machine worked by compressed
      air.

   {Pneumatic pile}, a tubular pile or cylinder of large
      diameter sunk by atmospheric pressure.

   {Pneumatic pump}, an air-exhausting or forcing pump.

   {Pneumatic railway}. See {Atmospheric railway}, under
      {Atmospheric}.

   {Pneumatic syringe}, a stout tube closed at one end, and
      provided with a piston, for showing that the heat produced
      by compressing a gas will ignite substances.

   {Pneumatic trough}, a trough, generally made of wood or sheet
      metal, having a perforated shelf, and used, when filled
      with water or mercury, for collecting gases in chemical
      operations.

   {Pneumatic tube}. See {Pneumatic dispatch}, above.
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