Pita

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Pitcn

ing against, a fluid pressure. It is usually
guided in its stroke by the walls of the cyl-
inder—of the chamber in which it works—
and also by the gland in the cylinder cover
through which the piston rod slides. Pistons
are generally made of cast iron, but in en-
gines for air craft, aluminum pistols are much
used.

Pita Hemp, one of the names of the
Agave fibre.

Pitaka, a division of the Buddhists' sacred
literature; the tripitdka meaning the three
great divisions of their canonical works, the
Vinaya (discipline), Abhidharma (metaphys-
ics), and Sutra (aphorisms in prose), and
collectively, the whole Buddhistic code.

Pit and Gallows, a rendering of the grant
of capital jurisdiction (cum fossa et jurca)
made by vassals to the British crown in
feudal times.

Pitcairn, Harold F. (1897- ), aviation
expert. He began building airplanes in 1925.
He is pres. of Pitcairn Aircraft, Inc., and of
the Autogiro Co., of America. In 1930 he
was awarded the Collier trophy for the
"greatest achievement in aeronautics,' —
the development of the autogiro.

Autogyro, a type of aircraft employing
horizonal rotatory airfoils, invented by Juan
de la Cieroa, Spanish aviator, and developed
by Harold F. Pitcairn. The propeller, an
ordinary form driven by a normal type of
engine, is mounted vertically above the fuse-
lage which is of standard airplane type, as
are also the landing gear and tail unit. Con-
trols are practically the same as *on an air-
plane, except the ailerons which are carried
on the sides of the fuselage. The great ad-
vantage of the autogiro is that it can make
practically vertical landings. It is expected
to become a safe and popular means of flying
with commercial production as planned.

In 1936 Pitcairn developed an autogiro
which is easily made serviceable as an auto-
mobile. The propeller wings fold back and
the motive power is geared to the landing
wheels, thus producing a roadable vehicle.
As an automobile the autogiro reaches a
speed of thirty-five miles per hour.

Pitcairn, John (c. 1740-75), British sol-
dier. He was in command of the advance
guard of British which entered Lexington on
April 19, 1775, and found the minute men
drawn up on the common. After ordering
them to disperse he gave the order to fire, and
is said to have fired the first shot himself. He
was mortally wounded at the Battle of
L»unker Hill (June 17,

Pitcairn, Robert (1836-1909), American
railway manager, was born near Paisley,
Scotland. In 1867 he helped organize the
Westinghouse Air Brake Company, and was
for many years its vice-president.

Pitcairn Island, a solitary island in the
Pacific Ocean, between Australia and South
America. Area, i by 2^2 m. It was dis-
covered by Carteret in 1767. In 1790 it was
taken possession of by nine of the mutineers
of H.M.S. Bounty with six Tahitian men
and a dozen women. Of nine British sailors,
only one, Adams, was left in 1800, and from
him the present inhabitants (150) are de-
scended. The island was annexed to Britain
in 1839. Nearly 200 of the islanders were
transferred to Norfolk Island in 1856, but a
number of them afterward returned.

In 1932 Norman Hall and Charles Nord-
hoff collaborated on a book Mutiny on the
Bounty, which was based on the story of the
mutineers. The book had a tremendous sale,
remaining on the list of best sellers for many
months, and was later screened.

Pitch, the angle of slope of a roof; the dis-
tance from center to center of the teeth of

Sir Isaac

a toothed wheel, or between like poles of a
dynamo, or between threads of a screw; the
distance apart of rivets.

Pitch, in music, the degree of acuteness of
musical sounds, determined by the series 01
periodic vibrations which produce the sound ;
the more rapid the vibrations the higher the
sound, and vice versa. The pitch of musical