nt of work it can do, is
likewise proportionately reduced.

Some seem to imagine, without thinking, that the elasticity of the air
can add additional energy. This is perfectly erroneous; for elasticity is
a mere property, which permits a body to be compressed on the application
of a force, and to be dilated by the exercise of the force stored up in
it by the compression. No property of the air can impart any energy. If
the momentum of a molecule or a series of molecules extending in all
directions for a mile is to be overcome so as to control the character of
the movements of the molecules, then sufficient _external_ energy must be
applied to accomplish the task: and when we think that one cubic inch of
air contains 3,505,519,800,000,000,000 molecules, to say nothing about
the number in a cubic mile, which a locust can transmit sound through, we
are naturally compelled to stop and think whether the vibrations of
_supposed_ molecules have anything or can have anything to do with the
transference of sound through the air.

If control was only had of the distance the vibrating molecule travels
from its start to the end of its journey, then only the intensity of the
sound would be under subjection; but if at every _infinitesimal instant_
control was had of its amplitude of swing, then the character, timbre, or
quality of the sound is under subjection. It is evident, then, that the
blows normally given by one molecule to another in their supposed
constant bombardment must not be sufficient to alter the character of
vibration a molecule set in oscillation by a sounding body must maintain,
to preserve the timbre or quality of the sound in process of
transmission; for if any such alteration should take place, then,
naturally, while the pitch, and perhaps intensity, might be transmitted,
the quality of the sound would be destroyed.

Again, it is certain that no molecule can perform two sets of vibrations,
two separate movements, at the same time, any more than it can be in two
places at the same time.

When a band of music is playing, the molecule is supposed to make a
complex vibration, a resultant motion of all acting influences, which the
ear is supposed to analyze. It remains for the mathematician to show how
a molecule influenced by twenty or more degrees of applied energy, and
twenty or more required number of frequences of vibration at the same
time, can establish a resultant motion which will transmit the required
pi