fundamental state. By this
means we eliminate all familiar intonation, and disassociate it from any
meaning which will sway the mind, and in this way it can be studied to
advantage. [Sidenote: THE SOUND WAVES] At a given rate of speed I have
taken the record of certain sounds made by a monkey, and by reducing the
rate of speed from two hundred revolutions per minute to forty, it can
be seen that I increased the intervals between what is called the sound
waves and magnified the wave itself fivefold, at the same time reducing
the pitch in like degree, and by this means I could detect the slightest
shades of modulation. I may remind you here that in this process all
parts of the sound are magnified alike in all directions, so that
instead of obtaining five times the length, as it were, of the sound
unit or interval, we obtain the cube of five times the normal length of
every unit of the sound. The slightest variation of tension in the vocal
chords may be detected, and every part of the sound compared to every
other part.

Having thus augmented the quantity of sound, by increasing alike the
sound unit and interval, it can be recorded on another cylinder and
multiplied again as long as the vibrations can produce sound. From the
constant relation of parts and their uniform augmentations under this
treatment, it has suggested to my mind the idea that all sounds have
definite geometrical outlines, and as we change the magnitude without
changing the form of the sound, I shall describe this constancy of form
by the term contour.

In a few instances I have been able, by reducing the record of certain
sounds from a high pitch to a lower one, to imitate the sound thus
reduced with my own vocal organs, then by restoring this record of my
voice to its normal speed have obtained almost a perfect imitation of
the sound. This effect, however, does not always follow, and in many
instances my best imitations have not developed the original at all. But
this presents a new problem in acoustics. I must here take occasion to
say that the difference of pitch, quality, &c., in sounds does not
appear to me to depend alone upon the length of the sound unit, but
there seems to be a difference of ultimate form and mode of propagation
which have much to do with the contour of the developed sound.

[Sidenote: THE SOUND FORCE]

By _mode of propagation_ I mean the organs brought into use for the
purpose of producing the sound, the apertures through