e diameter of the supposed molecules
of the air is about 1/250000000 of an inch (Tait); that the distance
between the molecules is about 8/100000 of an inch; that the velocity of
the molecules is about 1,512 feet a second at 0 deg.C., in its free path;
that the number of molecules in a cubic inch at 0 deg.C. is
3,505,519,800,000,000,000 or 35 followed by 17 ciphers (35)^{17}; and
that the number of collisions per second that the molecules make is,
according to Boltzmann, for hydrogen, 17,700,000,000, that is to say, a
hydrogen molecule in one second has its course wholly changed over
seventeen billion times. Assuming seventeen billion or million to be
right for the supposed air molecules, we have a very interesting problem
to consider.

The wave theory of sound requires, if we expect to hear sound by means of
a C^{3} fork of 256 vibrations, that the molecules of the air composing
the sound wave must not be interfered with in such a way as to prevent
them from traveling a distance of at least 1/50 to 1/1000000 of an inch
forward and back in the 1/256 of a second. The problem we have to explain
is, how a molecule traveling at the rate of 1,512 feet a second through a
mean path of 8/100000 of an inch, and colliding seventeen billion or
million times a second, can, by the vibration of the C^{3} fork, be made
to vibrate so as to have a pendulous motion for 1/256 of a second and
vibrate through a distance of 1/50 to the 1/1000000 of an inch without
being changed or mar its harmonic motion.

It is claimed that the range of sound lies between 16 vibrations and
30,000 (about); in such extreme cases the molecules would require 1/16
and 1/30000 of a second to perform the same journey.

It must not be forgotten that a mass moving through a given distance has
the power of doing work, and the amount of energy it will exercise will
depend on _its_ velocity. Now, a molecule of oxygen or nitrogen,
according to modern science, is a _mass_ 1/250000000 of an inch in
diameter, and an oxygen molecule has been calculated to weigh
0.0000000054044 ounce. Taking this weight traveling with a velocity of
1,512 feet a second through an average distance of 8/100000 of an inch,
the battering power or momentum it would have can be shown to be in round
numbers capable of moving 1/200000 of an ounce.

Now, when the C^{3} tuning fork has been vibrating for some time, but
still sounding audibly, Prof. Carter determined that its amplitude of
stroke was