PITCH n.
iameter of a circle bears to its circumference; it is sometimes described by the number expressing the quotient obtained by dividing the number of teeth in a wheel by the diameter of its pitch circle in inches; as, 4 pitch, 8 pitch, etc. -- Pitch chain, a chain, as one made of metallic plates, adapted for working with…
PNEUMATIC; PNEUMATICAL a.
e 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. --…
POLYTYPE n.
, of an engraved block, matter in type, etc. (see citation); as, a polytype in relief. By pressing the wood cut into semifluid metal, an intaglio matrix is produced: and from this matrix, in a similar way, a polytype in relief is obtained. Hansard.