A Text-book on Sound

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Macmillan and Company, limited, 1908 - Sound - 687 pages
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Page 363 - F1g. 140. agitating the flame. The creaking of my boots sets it in violent commotion. The crumpling or tearing of a bit of paper, or the rustle of a silk dress, does the same. It is startled by the patter of a rain-drop. I hold a watch near the flame ; nobody hears its ticks ; but you all see their effect upon the flame.
Page 401 - C : c was sounding, and I examined the lower note with the resonator: sometimes it appeared loud and steady, at other times as if beating powerfully. On removing the resonator-attachment from the ear, the lower note was always heard to beat powerfully. The explanation was simple. When the nipples of the resonatorattachment fitted tightly into the ears, nothing reached the ear but the uniform vibrations of the resonator sounding C. But if there was the slightest looseness between the nipple and the...
Page 260 - ... of the centres of the ventral segments remain the same as in the open tube (the numerals for these on the cone in the diagram falling exactly under those for the open tube), the nodes are gradually further and further apart, dividing their respective ventral segments more and more unequally, until at the apex of the cone is a node common to all the notes.
Page 601 - ... only by one-third of its original value ; and if we could suppose the layer to be moving harmonically, it is obvious that the mean of the increased and diminished pressures would be largely in excess of the normal value. Though we are not entitled to assume the existence of harmonic vibrations when we take into account the second order of small quantities, yet this illustration gives the right idea. The excess of pressure in the...
Page 364 - It is to these tones, and not to the fundamental one, that our flame is sensitive. I utter a loud and sonorous u, the flame remains steady; I change the sound to o, the flame quivers ; I sound E, and now the flame is strongly affected.
Page 417 - G of the viola, — are covered with silver wire. Below the neck of the instrument, and passing beneath the bridge, are seven more strings, of metal, tuned in unison with the others, so aa to vibrate sympathetically with them ; thereby giving to the instrument a second resonance, full of sweetness and mystery.
Page 602 - This view is most clearly brought home, perhaps, by considering a parallel train of waves which issues normally from a source for one second, -travels for any length of time through space, and then falls normally on an absorbing surface for one second. During this last second, momentum is given up to the absorbing surface. During the first second, the same amount was given out by the source. If it is conserved in the meanwhile, we must regard it as travelling with the train. Since the pressure is...
Page 601 - The excess of pressure in the compression half is greater than its defect during the extension half, and the net result is an average excess of pressure — a quantity itself of the second order — on the reflecting surface. This excess in the compression half of a wave-train is connected with the extra speed which exists in that half, and makes the crests of intense sound-waves gain on the troughs.
Page 609 - But this theory becomes less and less adequate as the pitch falls. At a frequency of 256 the difference of intensities at the two ears is far from conspicuous. At 128 it is barely perceptible. But although the difference of intensities is so small, the discrimination of right and left is as easy as before. There is nothing surprising in the observation that sounds of low...
Page 605 - SsLSpl + — | x total energy (6), \_ <ia 2a) the a now denoting the velocity of infinitely small waves. This may be compared with (1). If we suppose the long cylinder of length / to be occupied by a train of progressive waves moving towards the piston, the integrated pressure • upon the piston during a time I/a should be equal to twice the momentum of the whole initial motion.

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