Romance of Modern Invention," pp. 166 foll.

Chapter XIV.

SOUND AND MUSICAL INSTRUMENTS.

Nature of sound--The ear--Musical instruments--The vibration of
strings--The sounding-board and the frame of a piano--The
strings--The striking mechanism--The quality of a note.

Sound differs from light, heat, and electricity in that it can be
propagated through matter only. Sound-waves are matter-waves, not
ether-waves. This can be proved by placing an electric bell under the
bell-glass of an air-pump and exhausting all the air. Ether still
remains inside the glass, but if the bell be set in motion no sound is
audible. Admit air, and the clang of the gong is heard quite plainly.

Sound resembles light and heat, however, thus far, that it can be
concentrated by means of suitable lenses and curved surfaces. An _echo_
is a proof of its _reflection_ from a surface.

Before dealing with the various appliances used for producing
sound-waves of a definite character, let us examine that wonderful
natural apparatus

THE EAR,

through which we receive those sensations which we call sound.

[Illustration: FIG. 133.--Diagrammatic sketch of the parts of the ear.]

Fig. 133 is a purely diagrammatic section of the ear, showing the
various parts distorted and out of proportion. Beginning at the left, we
have the _outer ear_, the lobe, to gather in the sound-waves on to the
membrane of the tympanum, or drum, to which is attached the first of a
series of _ossicles_, or small bones. The last of these presses against
an opening in the _inner ear_, a cavity surrounded by the bones of the
head. Inside the inner ear is a watery fluid, P, called _perilymph_
("surrounding water"), immersed in which is a membranic envelope, M,
containing _endolymph_ ("inside water"), also full of fluid. Into this
fluid project E E E, the terminations of the _auditory nerve_, leading
to the brain.

When sound-waves strike the tympanum, they cause it to move inwards and
outwards in a series of rapid movements. The ossicles operated by the
tympanum press on the little opening O, covered by a membrane, and every
time they push it in they slightly squeeze the perilymph, which in turn
compresses the endolymph, which affects the nerve-ends, and telegraphs a
sensation of sound to the brain.

In Fig. 134 we have a more developed sketch, giving in fuller detail,
though still not in their actual proportions, the components of the ear.
The oss