ory nerve. But sound is only a recognized sensation when
the waves of air are within a certain measurement, a maximum and minimum
of length. The rush of a whirlwind has no sound, except when arrested by
some object, and smaller waves of the vast billows of rolling air are
created. We say that the wind roars. But the tremendous currents above
us, which sweep along the vast masses of vapor, are noiseless until they
touch the earth, and some little trifling eddies are made in their lower
sweep by hills and trees and houses. It is then only noise. The ear
requires yet smaller waves of air to experience the sensation of tone.
The lowest note of a piano has barely enough of it to give a definite
idea. As the waves become shorter, the ear begins to be pleasantly
affected, and the realm of music is reached. Within a certain restricted
length of air-waves lies all of the pleasurable sensation which we call
musical tone. But as we rise in the scale the tone begins to become
uncertain, until the highest note of the instrument is again indefinite
noise. The attenuated tone-waves of Nature are also inappreciable by the
auditory nerves, and an obscure hum or buzz is all that can be
perceived, until, finally, the eye detects motion which the ear utterly
fails to perceive as sound. The results of the air-waves are appreciable
by sight and feeling; but the waves which are heard are not those which
create the disturbance in nature we see and feel. The wild gust which
seizes a tree and bows it to the earth is only heard when the branches
it sways, or the leaves which it rustles, give out a secondary and far
more attenuate series of waves. A locust, on a warm, sunny day, will
agitate the air around him with a series of waves which affect the ear
far more powerfully than the wind which sighs in the waving trees above
him. Thus sound is the answering sensation of the auditory nerve to the
touch of air-waves; and these waves must be within certain
circumscribed limits of magnitude to awaken that sensation at all. The
greater or less violence with which they strike the ear causes them to
appear loud or soft. We can imagine a development of the nerves, or of
the ear apparatus, which might allow them to be influenced by waves of
greater volume and less rapid flow, and also by those of diminished size
and accelerated movement The trumpet then does not sounds the ear
sounds, and in the ear alone lies the music that it makes. The deaf man,
whose audi