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.
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.
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.
8. (Mining) The limit of ground set to a miner who receives a share of
the ore taken out.
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.
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∞, of 45∞,
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
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.
Pitch"-black` (?), a. Black as pitch or tar.
Pitch"blende` (?), n. [1st pitch + blende.] (Min.) A pitch-black
mineral consisting chiefly of the oxide of uranium; uraninite. See
Uraninite.
Pitch"-dark`, a. Dark as a pitch; pitch-black.
Pitch"er (?), n. 1. One who pitches anything, as hay, quoits, a ball,
etc.; specifically (Baseball), the player who delivers the ball to the
batsman.