250 HAND-BOOK OF ACOUSTICS.
39. Describe the principle of the Graphic method of ascertaining the vibration number of a tuning-fork.
40. Given the vibration number of a musical sound, how can its wave length be determined ? What are the lengths of the sound waves emitted by 4 forks, which vibrate 128, 256, 512, and 1024 times per second, respectively? (Take velocity of sound as 1100).
41. The vibration number of a tuning-fork is 532. What will be the length of the sound wave it originates (1) in air at 32° Fah., (2) in air at 60° Fah. ?
42. If the length of a sound wave is 3 feet 6 inches when the velocity of sound is 1100 feet per second, what is the vibration number of the sound ?
43. Calculate the length of the sound wave emitted by an organ pipe, which produces C8 = 32
44. Calculate the length of the sound wave produced by a piccolo flute which is sounding C* = 4096.
45. What are the approximate vibration numbers of the highest and lowest sounds used in music ?
46. Give the vibration numbers of (1) the C in Handel's time, (2) the French Diapason normal, (3) a Concert Piano, and organ (approximately).
47. When a locomotive sounding its whistle is passing rapidly through a station, to a person on the platform, the pitch of the whistle appeal's sharper while the engine is approaching, than it does after it has passed him. Explain this.
48. What is meant by the vibration ratio of an interval ? If the vibration numbers of two sounds are 496 and 465 respectively, what is the vibration ratio of the interval between them ? What is this interval called ?
49. What are the vibration ratios of an Octave, a Fifth, and a Majoi Third?
50. What are the vibration ratios of a Major and Minor Sixth, and a Minor Third ?
51. What is the best way of experimentally proving that the vibration ratios of an Octave, Fifth and Major Third are exactly -*, £, and £ respec≠tively ?
52. Given that the vibration numbers of s, m, d, are as 6:5:4, and that d = 300; calculate from these data, the vibration numbers of the other tones of the Diatonic Scale.
63. Given d = 320, and that the vibration numbers of the tones of a Major Triad, in its normal position, are as 6 : 5 : 4; calculate from these data the vibration numbers of the other tones of the diatonic scale.
64. Given d = 256, and vibration ratios of a Fifth and Major Third are i and A respectively; calculate from these data, the vibration numbers of the other tones of the diatonic scale.