various other facts of
hearing--if we could only believe that the basilar membrane did
vibrate in this simple manner, fiber by fiber. But (1) the fabric into
which the strings of the membrane are woven would prevent their
vibrating as freely and independently as the theory requires; (2) the
strings do not differ in length a hundredth part of what they would
need to differ in order to be tuned to all notes from the lowest to
the highest, and there is no sign of differences in stretch or in
loading of the strings to make up for their lack of difference in
length; and (3) a little model of the basilar membrane, exposed to
sound waves, is seen to be thrown into vibration, indeed, and into
different forms of vibration for waves of different length, but not by
any means into the simple sort of vibration demanded by the piano
theory. This theory is accordingly too simple, but it probably points
the way towards some truer, more complex, conception.

The fact that there are many elementary sensations of hearing is the
chief reason why the art of tones is so much more elaborate than the
art of color; for while painting might dispute with music as to which
were the more highly developed art, painting depends on form as well
as color, and there is no art of pure color at all comparable with
music, which makes use simply of tones (and noises) with their
combinations and sequences.

{236}

Senses of Bodily Movement

It is a remarkable fact that some parts of the inner ear are not
connected with hearing at all, but with quite another sense, the
existence of which was formerly unsuspected. The two groups of sense
cells in the vestibule--the otolith organs--were formerly supposed to
be the sense organ for noise; but noise now appears to be a compound
of tones, and its organ, therefore, the cochlea. The _semicircular
canals_, from their arrangement in three planes at right angles to
each other, were once supposed to analyze the sound according to the
direction from which it came; but no one could give anything but the
vaguest idea of how they might do this, and besides the ear is now
known to give practically no information regarding the direction of
sound, except the one fact whether it comes from the right or left,
which is given by the difference in the stimulation received by the
two ears, and not by anything that exists in either ear taken alone.

The semicircular canals have been much studied by the physiologists.
They foun