RESPECTING SOUND AND LIGHT.

555

EXPLANATION OF THE FIGURES.

Plate 2. Fig. 4. . 9- The section of a stream of air from a tube .07 inch in diameter, asascertained by measuring the breadth of the impression on the surface of a liquid. The pres-sure, impelling the current, was in Fig. 4, 1 inch. Fig. 5, 2. Fig . (i, 3. Fig. 7, 4. Fig.8, 7. Fig. 9, 10.

Fig. 10. . 15. A similar section, where the tube was .1 in diameter, compared with thesection as inferred from the experiments with two gages, which is represented by a dottedline. From this comparison it appears, that where the velocity of the current was small, itsCentral parts only displaced the liquid; and that, where it was great, it displaced, on meet-ing with resistance, a surface somewhat greater than its own section. The pressure was inFig. 10, 1. Fig. 11, 2. Fig. 12,3. Fig. 13, 4. Fig. 14, 7. Fig. 15, 10.

Fig. 1(). .23. A, the half section of a stream of air from a tube .1 in diameter, as in-ferred from experiments with two water gages. The pressure was in Fig. 16, .1. Fig. 17, .2.Fig. 18, .5. Fig. 19, 1. Fig. 20, 3. Fig. 21, 5. Fig. 22, 7. Fig. 23, 10- The fine lines,marked B, show the result of the observations with an aperture .15 in diameter opposed tothe stream ; C with .3 ; and D with .5.

Fig. 24.. 26. A the half section of a current from a tube ,3 in diameter, with a pressureof .5, of 1, and of 3. B shows the course of a portion next the axis of the current, equalin diameter to those represented by the last figures.

Plate 3. Fig. 27. The appearance of a stream of smoke forced very gently from a finetube. Fig. 28 and 29, the same appearance when the pressure is gradually increased.

Fig . SO. A mouth piece for a sonorous cavity.

Fig. 31. The perpendicular lines over each division of the horizontal line show, by theirlength and distance from that line, the extent of pressure capable of producing, front therespective pipes, the harmonic notes indicated by the figures placed opposite the beginningof each, according to the scale of 22 inches parallel to them. The larger numbers, oppo-site the middle of each of these lines, show the number of vibrations of the correspondingsound in a second.

Plate 2. Fig. 32. . 35. Illustrations of the affections of light.

Fig. 36. The combination of two sounds.

Fig. 37. The combination of two equal sounds constituting the interval of an octavesupposing the progress and regress of the particles of air equable. Fig. 38, 39, 40, a simi-lar representation of a major third, major tone, aud minor sixth.

Fig. 41. A fourth, tempered about two commas.

Fig. 42. A vibration of a similar nature, combined with subordinate vibrations of the samekind in the ratios of 3, 5, and 7.

Fig. 43. A vibration represented by a curve of which the ordinates are the sines of circulara rcs increasing uniformly, corresponding with the motion of a cycloidal pendulum, com-bined with similar subordinate vibrations in the ratios of 3, 5, and 7.

v OL. 1J. 4 B