RESPECTING SOUXD AND LIGHT. 55S 



EXPLANATION OF THE FIGURES. 



Plate 2. Fig. 4. . 9. The section of a stream of air fjom a tube .07 inch in diameter, as 

 ascertained 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, G, 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 the 

 section as inferred from the experiments with two gages, which is represented by a dotted 

 line. From this comparison it appears, that where the velocity of the current was small, its 

 central 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 iu 

 Fig. 10, 1. Fig. 11,2. Fig. 12, 3. Fig. 13, 4. Fig. 14, 7. Fig. 15, 10. 



Fig. l6. .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. l6, .1. Fig. 17, .2. 

 Fig. 18, .5. Fig. 19, 1. Fig. 20, 3. Fig. 21, 5. Fig. 22, 7- Fig. 23, 10- Tlie fine lines, 

 marked B, show the result of the observations with an aperture .15 in diameter opposed to 

 the stream ; C with. 3; and]) with .5. 



Fig. 24. . 26. A the half section of a current from a tube .3 in diameter, with a pressure 

 of .5, of 1, and of 3. B shows the course of a portion next the axis of the current, equal 

 in diameter to those represented by the last figures. 



Plate 3. Fig. 27. The appearance of a stream of smoke forced very gently from a fine 

 tube. Fig. 28 and 29, the same appearance when the pressure is gradually increased. 



Fig. 30. A mouth piece for a sonorous cavity. 



Fig. 31. The perpendicular lines over each division of the horizontal line show, by their 

 length and distance from that line, the extent of pressure capable of producing, from the 

 respective pipes, the harmonic notes indicated by the figures placed opposite the beginning 

 of 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 corresponding 

 sound in a second. 



Plates. 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 octave 

 supposing the progress and regress of the particles of air equably Fig. 38, 39, 40, a simi- 

 lar representation of a major third, major tone, and minor sixths" 



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



Fig. 42. A vibration of a similar nature, combined with subordinate vibrations of the same 

 kind in the ratios of 3, 5, and 7- 



Fig. 43. A vibration aepresented by a curve of which the ordinates are the sines of circular 

 arcs increasing uniformly, corresponding with the motion of a cycloidal pendulum, com- 

 bined with similar- subordinate vibrations in the ratios of 3, 5, and 7. 



VOL. II. 4 B 



