Pitch

Collier's New Encyclopedia (1921)

a term applied to a variety of resinous substances of a dark color and brilliant luster, obtained from the various kinds of tar produced in the destructive distillation of wood, coal, etc. In architecture, the rise or versed sine of an arch. In carpentry, the inclination of a roof. The common pitch has a rafter three-quarters the length of the span; the Gothic has a full pitch; the rafters being the length of the span; the Greek has a pitch 16 to 14 of the span; the Roman has a pitch from 1% to 2% of the span; and the Elizabethan has rafters longer than the span. In hydraulic engineering, in overshot water wheels the bucket-pitch is a circular line passing through the elbows of the buckets. The elbow is the junction of the floor and the arm, which together form the bucket. In machinery: (1) the distance between the threads of a screw measured on a line parallel to the axis. (2) The distance between the centers of two adjacent teeth in a cogwheel, measured on the pitch circle. (3) The pitch of a rivet is the distance apart from center to center. (4) The distance between the stays of marine and other steam boilers. In marine boilers it is usually from 12 to 18 inches. In mining, a lode or portion of SIR ISAAC PITMAN produces yams, cocoanuts, bread fruit, a lode let out to men to work by the sweet potatoes, bananas, etc. Pop. piece or by a percentage of the output. In music, musical sounds give to the mind a feeling of acuteness or gravity according to the rapidity or slowness of the vibrations producing them; hence, the former are called acute or high, the latter grave or low. The absolute pitch of sounds is measured by giving the number of vibrations per second which produces a given sound, e. g., C = 528; the relative pitch of sounds is described by giving the ratio of vibrations of the interval, e. g., a fifth is 2:3-that is, the higher sound of any interval of a fifth gives three vibrations, while the lower sound in the same time gives two. The determination of fixed pitch is purely arbitrary, and it has from time to time undergone great variations. In England we have high concert pitch C = about 540, more or less, and the medium pitch C = 528; on the Continent the French "diapason normal," C = 518, is being largely adopted. The official standard adopted in the United States during the world's fair was what is known as international or "French" pitch, which gives as a standard middle A with 435 vibrations, though the majority of American upright pianos are tuned to high concert subject pitch. In planes, the slant of a plane bit in edition In printing, one of the guide porter's its stock. ock. pins, which, in floor - cloth printing, an- the swers the purpose of the register points. Bath, In shipbuilding: ( 1) The pitch of the ing paddles is the distance between them, and measured on the circle which passes through their centers. It is commonly United from 1.6 to double their depth. ( 2) The pitch of a propeller - screw is the length, from measured along the axis, of a complete ter turn. A gaining - pitch is one in which ristown the pitch gradually increases from the Congress leading to the following edge.