Pillar Model—A type of movement in which the works are hung between two plates supported and separated by posts or pillars and forming all the principal bearings of the movement. Only average adjustment is possible in this model. In this model the plate is sometimes cut away to imitate a "bridge model." The opposite extreme in construction to the "bridge model."
Pillar Plate—The lower plate of a watch movement—the one nearest the dial—to which the pillars are solidly fixed, in a "pillar model."
Pinchbeck, or "Pinchbeck Gold"—An alloy of three parts zinc to four of copper which "resembles gold in color, smell and ductility." So called from its inventor Christopher Pinchbeck (1670-1732) who during his life guarded the secret of its composition very jealously.
Pinion—The smaller of two toothed wheels that work together. The teeth of a pinion are called leaves. See also [Lantern Pinion].
Pinion, Lantern—A pinion consisting of two circular metal plates joined by short steel wires.
Pitch—The length of the arc of the circumference of the pitch circle from center to center of two adjacent teeth.
Pitch Circle—The geometrical circle traced with the center of the wheel as its center and at which the curved tips of the teeth begin. The diameter is proportional to the number of teeth determined upon. The proportion of the pitch circles of a wheel and a pinion gearing together is determined by the ratio of revolutions desired.
Pitkin, Henry—With his brother, James F., he started at Hartford, Conn., in 1838, the first factory for machine-made watches in the United States. They made their own machinery, which was very crude. After making about 800 watches they were forced to abandon the project, being unable to compete with cheap foreign watches. He died in 1845.