only the 1/17000 of an inch, or its velocity of motion was at
the rate of 1/33 of an inch in one second, or one inch in 33 seconds
(over half a minute), or less than one foot in one hour.

Assuming one prong to weigh two ounces, we have a two-ounce mass moving
1/17000 of an inch with a velocity of 1/33 of an inch in one second. The
prong, then, has a momentum or can exercise an amount of energy
equivalent to 1/200 of an ounce, or can overcome the momentum of 1,000
molecules.

It would be difficult to discover not only how a locust can expend
sufficient energy to impart to molecules of the air, so as to set them in
a _forced_ vibration, and thus enable a pulse of the energy imparted to
control the motion of the supposed molecules of the air for a mile in all
directions, but also to estimate the amount of energy the locust must
expend.

According to the wave theory, a condensation and rarefaction are
necessary to constitute a sound wave. Surely, if a condensation is not
produced, there can be no sound wave! We have then no need to consider
anything but the condensation or compression of the supposed air
molecules, which will shorten the discussion. The property of mobility of
the air and fluidity of water are well known. In the case of water, which
is almost incompressible, this property is well marked, and
unquestionably would be very nearly the same if water were wholly
incompressible. In the case of the air, it is conceded by Tyndall,
Thomson, Daniell, Helmholtz, and others that any compression or
condensation of the air must be well marked or defined to secure the
transmission of a sound pulse. The reason for this is on account of this
very property of mobility. Tyndall says: "The prong of the fork in its
swift advancement condenses the air." Thomson says: "If I move my hand
vehemently through the air, I produce a condensation." Helmholtz says:
"The pendulum swings from right to left with a uniform motion. Near to
either end of its path it moves slowly, and in the middle fast. Among
sonorous bodies which move in the same way, only very much faster, we may
mention tuning forks." Tyndall says again: "When a common pendulum
oscillates, it tends to form a condensation in front and a rarefaction
behind. But it is only a tendency; the motion is so slow, and the air so
elastic, that it moves away in front before it is sensibly condensed, and
fills the space behind before it can become sensibly dilated. Hence waves
or pul