Diametral pitch

Pitch Pitch, n. 1. A throw; a toss; a cast, as of something from the hand; as, a good pitch in quoits. [1913 Webster]

{Pitch and toss}, a game played by tossing up a coin, and calling ``Heads or tails;'' hence:

{To play pitch and toss with (anything)}, to be careless or trust to luck about it. ``To play pitch and toss with the property of the country.'' --G. Eliot.

{Pitch farthing}. See {Chuck farthing}, under 5th {Chuck}. [1913 Webster]

2. (Cricket) That point of the ground on which the ball pitches or lights when bowled. [1913 Webster]

3. A point or peak; the extreme point or degree of elevation or depression; hence, a limit or bound. [1913 Webster]

Driven headlong from the pitch of heaven, down Into this deep. --Milton. [1913 Webster]

Enterprises of great pitch and moment. --Shak. [1913 Webster]

To lowest pitch of abject fortune. --Milton. [1913 Webster]

He lived when learning was at its highest pitch. --Addison. [1913 Webster]

The exact pitch, or limits, where temperance ends. --Sharp. [1913 Webster]

4. Height; stature. [Obs.] --Hudibras. [1913 Webster]

5. A descent; a fall; a thrusting down. [1913 Webster]

6. The point where a declivity begins; hence, the declivity itself; a descending slope; the degree or rate of descent or slope; slant; as, a steep pitch in the road; the pitch of a roof. [1913 Webster]

7. (Mus.) The relative acuteness or gravity of a tone, determined by the number of vibrations which produce it; the place of any tone upon a scale of high and low. [1913 Webster]

Note: Musical tones with reference to absolute pitch, are named after the first seven letters of the alphabet; with reference to relative pitch, in a series of tones called the scale, they are called one, two, three, four, five, six, seven, eight. Eight is also one of a new scale an octave higher, as one is eight of a scale an octave lower. [1913 Webster]

8. (Mining) The limit of ground set to a miner who receives a share of the ore taken out. [1913 Webster]

9. (Mech.) (a) The distance from center to center of any two adjacent teeth of gearing, measured on the pitch line; -- called also circular pitch. (b) The length, measured along the axis, of a complete turn of the thread of a screw, or of the helical lines of the blades of a screw propeller. (c) The distance between the centers of holes, as of rivet holes in boiler plates. [1913 Webster]

10. (Elec.) The distance between symmetrically arranged or corresponding parts of an armature, measured along a line, called the pitch line, drawn around its length. Sometimes half of this distance is called the pitch.

{Concert pitch} (Mus.), the standard of pitch used by orchestras, as in concerts, etc.

{Diametral pitch} (Gearing), the distance which bears the same relation to the pitch proper, or circular pitch, that the diameter 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 a sprocket wheel.

{Pitch line}, or {Pitch circle} (Gearing), an ideal line, in a toothed gear or rack, bearing such a relation to a corresponding line in another gear, with which the former works, that the two lines will have a common velocity as in rolling contact; it usually cuts the teeth at about the middle of their height, and, in a circular gear, is a circle concentric with the axis of the gear; the line, or circle, on which the pitch of teeth is measured.

{Pitch of a roof} (Arch.), the inclination or slope of the sides expressed by the height in parts of the span; as, one half pitch; whole pitch; or by the height in parts of the half span, especially among engineers; or by degrees, as a pitch of 30[deg], of 45[deg], etc.; or by the rise and run, that is, the ratio of the height to the half span; as, a pitch of six rise to ten run. Equilateral pitch is where the two sloping sides with the span form an equilateral triangle.

{Pitch of a plane} (Carp.), the slant of the cutting iron.

{Pitch of poles} (Elec.), the distance between a pair of poles of opposite sign.

{Pitch pipe}, a wind instrument used by choristers in regulating the pitch of a tune.

{Pitch point} (Gearing), the point of contact of the pitch lines of two gears, or of a rack and pinion, which work together. [1913 Webster]