The pneumatical substance being, in some bodies, the
native spirit of the body. --Bacon.
2. Of or pertaining to air, or to elastic fluids or their
properties; pertaining to pneumatics; as, pneumatic
experiments. ``Pneumatical discoveries.'' --Stewart.
3. Moved or worked by pressure or flow of air; as, a
pneumatic instrument; a pneumatic engine.
4. (Biol.) Fitted to contain air; Having cavities filled with
air; as, pneumatic cells; pneumatic bones.
{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.