served as a bar to discovery in many of the arts. So extremely
simple have been some of the keys that many inventions resulted from
accidents.

INVENTION PRECEDES SCIENCE.--Occasionally inventions were brought about
by persistency and energy, and ofttimes by theorizing; but science
rarely ever aids invention. The latter usually precedes science. Thus,
reasoning could not show how it might be possible for steam to force
water into a boiler against its own pressure. But the injector does
this.

If, prior to 1876, it had been suggested that a sonorous vibration could
be converted into an electrical pulsation, and transformed back again to
a sonorous vibration, science would have proclaimed it impossible; but
the telephone does it. Invention shows how things are done, and science
afterwards explains the phenomena and formulates theories and laws which
become serviceable to others in the arts.

SIMPLICITY IN INVENTIONS.--But let us see how exceedingly simple are
some of the great discoveries of man.

THE TELEGRAPH.--The telegraph is nothing but a magnet at each end of a
wire, with a lever for an armature, which opens and closes the circuit
that passes through the magnets and armature, so that an impulse on the
lever, or armature, at one end, by making and breaking the circuit, also
makes and breaks the circuit at the other end.

TELEPHONE.--The telephone has merely a disk close to but not touching
the end of a magnet. The sonorous vibration of the voice oscillates the
diaphragm, and as the diaphragm is in the magnetic field of the magnet,
it varies the pressure, so called, causing the diaphragm at the other
end of the wire to vibrate in unison and give out the same sound
originally imparted to the other diaphragm.

TRANSMITTER.--The transmitter is merely a sensitized instrument. It
depends solely on the principle of light contact points in an electric
circuit, whereby the vibrations of the voice are augmented.

PHONOGRAPH.--The phonograph is not an electrical instrument. It has a
diaphragm provided centrally with a blunt pin, or stylus. To make the
record, some soft or plastic material, like wax, or tinfoil, is caused
to move along so that the point of the stylus makes impressions in it,
and the vibrations of the diaphragm cause the point to traverse a groove
of greater or smaller indentations. When this groove is again presented
to the stylus the diaphragm is vibrated and gives forth the sounds
originally imparted t