Evolution of Sound: Part of the Problem of Human Life Here and Hereafter Containing Reviews of Tyndall, Helmholtz and Mayer

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Hall, 1878 - 527 páginas
 

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Página 256 - We could thus transmit a push through a row of a hundred boys, each particular boy, however, only swaying to and fro. Thus, also, we send sound through the air and shake the drum of a distant ear, while each particular particle of the air concerned in the transmission of the pulse makes only a small oscillation.
Página 259 - ... long since have disappeared from works on science, and physicists of to-day would be looking back with astonishment at the superficiality and stupidity of their brethren of the past, just as astronomers of the present time are often amazed at the want of perspicacity in mathematicians of the Ptolemaic school, who believed the earth to be the center of the universe, and that the sun, moon, and stars revolved around it every twenty-four hours. As inconceivable as it must seem to the scientific...
Página 101 - 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 300 - If this be the case the two forks will assist each other. The condensations will, in fact, become more condensed, the rarefactions more rarefied, and as it is upon the difference of density between the condensations and rarefactions that loudness depends, the two vibrating forks, thus supporting each other, will produce a sound of greater intensity than that of either of them vibrating alone. It is, however, also easy to see that the two forks may be so related to each other that one of them shall...
Página 131 - To account for the enormous velocity of propagation in the case of light, the substance which transmits it is assumed to be of both extreme elasticity and of extreme tenuity. This substance is called the Luminiferous ether: It fills space; it surrounds the atoms of bodies; it extends, without solution of continuity, through the humors of the eye. The molecules of luminous bodies are in a state of vibration. The vibrations are taken up by the ether...
Página 171 - Thus is sound conveyed from particle to particle through the air. The particles which fill the cavity of the ear are finally driven against the tympanic membrane, which is stretched across the passage leading to the brain. This membrane, which closes outwardly the
Página 252 - The same air is competent to accept and transmit the vibrations of a thousand instruments at the same time. When we try to visualise the motion of that air — to present to the eye of the mind the battling of the pulses direct and reverberated — the imagination retires baffled from the attempt.
Página 252 - But if the condensations of the one system coincide with the rarefactions of the other, a destruction total or partial of both systems is the consequence. ... If the two sounds be of the same intensity their coincidence produces a sound of four times the intensity of either; while their interference produces absolute silence."—Lectures on Sound, pp. 284, 285. There is no misunderstanding this citation; for if two systems of equal waves from two unison forks, for example, ";'«terfere" by the forks...
Página 106 - Then, to show what he means by the transmission of this "motion" "to every other point of the atmosphere," he continues, without break, to use the illustration of the tube,of which I have spoken:— "Thus, if we imagine a tube open at one end and closed at the other by a piston that moves in the tube without friction, it is evident that if this piston were pushed into the tube a certain distance the air would at the same time move out of the tube at the open end.
Página 282 - We have here a phenomenon which, above all others, characterises wave-motion. It was this phenomenon, as manifested in optics, that led to the undulatory theory of light, the most cogent proof of that theory being based upon .the fact that, by adding light to light, we may produce darkness, just as we can produce silence by adding sound to sound.

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