pitch point

Pitch \Pitch\, n.
   1. A throw; a toss; a cast, as of something from the hand;
      as, a good pitch in quoits.
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   {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}.
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   2. (Cricket) That point of the ground on which the ball
      pitches or lights when bowled.
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   3. A point or peak; the extreme point or degree of elevation
      or depression; hence, a limit or bound.
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            Driven headlong from the pitch of heaven, down
            Into this deep.                       --Milton.
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            Enterprises of great pitch and moment. --Shak.
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            To lowest pitch of abject fortune.    --Milton.
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            He lived when learning was at its highest pitch.
                                                  --Addison.
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            The exact pitch, or limits, where temperance ends.
                                                  --Sharp.
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   4. Height; stature. [Obs.] --Hudibras.
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   5. A descent; a fall; a thrusting down.
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   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.
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   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.
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   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.
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   8. (Mining) The limit of ground set to a miner who receives a
      share of the ore taken out.
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   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.
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   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.
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