Part 362

Bacon.

Boswell, and others of Goldsmith's contemporaries, . . . did not understand the secret plies of his character.

W. Irving.

The czar's mind had taken a strange ply, which it retained to the last.

Macaulay.

Ply is used in composition to designate folds, or the number of webs interwoven; as, a three-ply carpet.

Ply"er (?), n. One who, or that which, plies; specifically: (a) pl. A kind of balance used in raising and letting down a drawbridge. It consists of timbers joined in the form of a St. Andrew's cross. (b) pl. See Pliers.

Plyght (?), v. & n. See Plight. [Obs.] Chaucer.

Plym"outh Breth"ren (?). The members of a religious sect which first appeared at Plymouth, England, about 1830. They protest against sectarianism, and reject all official ministry or clergy. Also called Brethren, Christian Brethren, Plymouthists, etc. The Darbyites are a division of the Brethren.

Pne*om"e*ter (?), n. [Gr. &?; to breathe + -meter.] (Physiol.) A spirometer.

{ Pneu*mat"ic (?), 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.

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.

Pneu`ma*tic"i*ty (?), n. (Biol.) The state of being pneumatic, or of having a cavity or cavities filled with air; as, the pneumaticity of the bones of birds.

Pneu*mat"ics (?), n. [Cf. F. pneumatique.]

1. That branch of science which treats of the mechanical properties of air and other elastic fluids, as of their weight, pressure, elasticity, etc. See Mechanics.

2. (Philos. & Theol.) The scientific study or knowledge of spiritual beings and their relations to God, angels, and men.

Pneu"ma*to- (n"m*t- or n*mt"-). A combining form from Gr. pney^ma, pney`matos, wind, air, breath, respiration; as, pneumatograph, pneumatology. [1913 Webster]

Pneu*mat"o*cele (?), n. [Pneumato- + Gr. &?; a tumor; cf. F. pneumatocËle.] (Med.) A distention of the scrotum by air; also, hernia of the lungs.

Pneu*mat"o*cyst (?), n. [Pneumato- + cyst.] (Zoˆl.) A cyst or sac of a siphonophore, containing air, and serving as a float, as in Physalia.

Pneu*mat"o*garm (?), n. [Pneumato- + -gram.] (Physiol.) A tracing of the respiratory movements, obtained by a pneumatograph or stethograph.

Pneu*mat"o*graph (?), n. [Pneumato- + -graph.] (Physiol.) An instrument for recording the movements of the thorax or chest wall during respiration; -- also called stethograph.

Pneu`ma*to*log"ic*al (?), a. [Cf. F. pneumatologique.] Of or pertaining to pneumatology.

Pneu`ma*tol"o*gist (?), n. [Cf. F. pneumatologiste.] One versed in pneumatology.