260 HAND-BOOK OF ACOUSTICS.
219. Two harmonium reeds, the vibration numbers of which are 199 and 251, produce slow beats when sounded together. Explain the reason. How many beats per second will be heard ?
220. Two forks, the vibration numbers of which are 256 and 168, produce faint beats when sounded together. How many beats per second will be heard?
221. How many audible beats per second will two harmonium reeds generate, which vibrate 149 and 301 times per second respectively ?
222. How is the interval of an Octave between Simple Tones defined?
223. How would you proceed to tune two Simple Tones to the interval of a perfect Fifth; 1st, if you had no other tones to assist you, and 2nd, if you already possessed the Octave of one of the tones ?
224. How are the intervals of a Fifth and Fourth between Simple Tone* defined ?
225. How are the intervals of an Octave and a Fifth between Compound Tones defined ?
226. Explain the principle involved in tuning two violin strings at the interval of a perfect Fifth.
227. In the interval of a Fourth, why is it necessary that the vibration numbers of the two tones should be in the exact ratio of 4 : 3 ?
228. If two harmonium reeds vibrate 501 and 399 times per second respectively, how many beats per second will be heard when they are sounded together ?
229. The vibration numbers of the C and EAy in an equal-tempered harmonium are 264 and 314 respectively; how many beats per second will be heard when they are sounded together ?
230. On an equal-tempered harmonium, C = 264 and A = 444. When they are sounded together, how many beats per second will be heard ?
231. Two harmonium vibrators an exact Octave apart are sounded together. Explain fully the result of again sounding them together after one of them has been flattened by one vibration per second.
232. How is the Octave defined, in the case of stopped organ pipes, the tones of which consist of the 1st and 3rd partials only ?
233. Which is the easier interval to tune, and why:—the Fifth or Major Third?
234. Two tones are sounded on a harmonium, the vibration numbers of which are 300 and 401 respectively. How many beats per second may be counted ?