Page:Young - Outlines of experiments and inquiries respecting sound and light (1800).djvu/17

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12
Dr. Young's Experiments and Inquiries
Table ix. Table x.
A 1.15 3.3 4. Diameter of the tube .3.
A, B, C, and D, as in Table vii.
A B A is the pressure. B, the distance of the apex of the cone from the orifice of a tube .1 in diameter.
B .15 .3 .5 1. .06 .15 1. .06 0.4
0.8
1.2
1.8
2.
4.
6.
3.
1.5
1.
0.5
0.0
C D D D D D D D D
0.5
1.
2.
3.
.1
.2
.4
.6
.1
.2
.35
.5
.1
.2
.34
.5


.13
.2


.1
.15


.1
.15


.125
.18



.1
III. Ocular Evidence of the Nature of Sound.

A tube about the tenth of an inch in diameter, with a lateral orifice half an inch from its end, filed rather deeper than the axis of the tube, Fig. 27, was inserted at the apex of a conical cavity containing about twenty cubic inches of air, and luted perfectly tight: by blowing through the tube, a sound nearly in unison with the tenor C was produced. By gradually increasing the capacity of the cavity as far as several gallons, with the same mouth-piece, the sound, although faint, became more and more grave, till it was no longer a musical note. Even before this period a kind of trembling was distinguishable; and this, as the cavity was still further increased, was changed into a succession of distinct puffs, like the sound produced by an explosion of air from the lips; as slow, in some instances, as 4 or 3 in a second. These were undoubtedly the single vibrations, which, when repeated with sufficient frequency, impress on the auditory nerve the sensation of a continued sound. On forcing a current of smoke through the tube, the vibratory motion of the stream, as it passed out at the lateral orifice, was evident to the eye; although, from various circumstances, the quantity and direction of its motion could not be subjected to