A Text-book on Sound: The Substantial Theory of Acoustics Adapted to the Use of Schools, Colleges, Etc

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Hall & Company, 1887 - 236 páginas
 

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Página 207 - I blow the candle out. You may here observe, in a rough way, the speed with which the sound-wave is propagated. The instant I clap, the flame is extinguished; there is no sensible interval between the clap and the extinction of the flame. I do not say that the time required by the sound to travel through this tube is immeasurably short, but simply that the interval is too short for your senses to appreciate it. To show you that it is a pulse and not a puff of air, I fill one end of the tube with...
Página 208 - The most striking example of this inflection of a sonorous wave that I have ever seen, was exhibited at Erith after the tremendous explosion of a powder magazine which occurred there in 1864. The village of Erith was some miles distant from the magazine, but in nearly all cases the windows were shattered ; and it was noticeable that the windows turned away from the origin of the explosion suffered almost as much as those which faced it. Lead sashes were employed in Erith church, and these being in...
Página 194 - ... the air into waves, as Prof. Tyndall expresses it, just to the same extent exactly as when in connection with its sounding-tray, yet its sounds can scarcely be heard by a person standing near it, for the want of a resonant body to augment its tone by diffusion, as will be explained after a little. A string in this condition will not start a unison body into sympathetic vibration even if but a few inches distant, and then only in exact proportion to the intensity of its sound, and not at all in...
Página 193 - ... possible without touching, being careful that their supports had no immediate connection (except the air) by which any impulse might be communicated from the moving ball to the one at rest. Though their swings were in perfect synchronism, moving with twice the aggregate velocity of a tuning-fork's prongs, and although they were so near together that the air-disturbances caused by the moving pendulum must necessarily strike the other periodically, or as nearly so as it is possible for air-waves...
Página 193 - ... tone is produced by these vibrations no motion whatever will be communicated to the unison neighbor, though it necessarily and continuously receives the synchronous air- waves driven against it by the actuating body. I have carefully tested this in the following manner: I arranged two pendulum-balls, with very short rods of equal length, to cause rapid swings as closely together as possible without touching, being careful that their supports had no immediate connection (except the air) by which...
Página 177 - Imagine one of the prongs of the vibrating fork swiftly advancing ; it compresses the air immediately in front of it, and when it retreats it leaves a partial vacuum behind, the process being repeated by every subsequent advance and retreat. The whole function...
Página 208 - The village of Erith was some miles distant from the magazine, but in nearly all cases the windows were shattered ; and it was noticeable that the windows turned away from the origin of the explosion suffered almost as much as those which faced it. Lead sashes were employed in Erith church, and these being in some degree flexible, enabled the windows to yield to pressure without much fracture of the glass. Every window in the church, front and back, was bent inwards. In fact, as the sound-wave reached...
Página 217 - As this is known not to be the case (see answer 32), it follows that the wavetheory cannot be true, and therefore that sound must consist of something besides atmospheric pulses. What else is there for sound to be, unless it be a substantial force? no distinction whatever in the velocity of the condensed wave thus generated, whether the piston is moved one inch or ten feet so the movement is instantaneous; and, consequently, he points out no difference in the speed of such a pulse, whether the spring-force...
Página 208 - sonorous wave" which inflected, and doubled its two ends around the building, thus crushing the windows!] Lead sashes were employed in Erith church, and these being in some degree flexible, enabled the windows to yield to the pressure without much fracture of the glass. Every window in the church, front and back, was bent inwards. In fact, as the sound-wave reached the church it separated right and left, and fcr a moment the edifice was clasped by a.
Página 216 - ... produce, or what distance it should be instantaneously driven into the tube. Dr. Hall was the first writer to call this law in question, as he was the first to announce the numerous abrupt departures from physical science set forth in this chapter.* * The foregoing being the unperverted and undeniable logic of physicists, let us for a few minutes turn to the record. By reference to " Appleton's American Encyclopedia'' and its elegantly written article on " Sound," fortunately within the reach...

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