IQ^ TRANSMISSION OF SOUND THROUGH LONG TUBES. 



Luss-ic. A stroke of a hammer ; gainst the si le of tha 

 gallery produced two sounds, which separated at a certain 

 distance, and that transmitted by the stone arrived first, 

 This separation too was observed, when the sound was 

 transmitted throu}^h iron bars, or wooden rails of different 

 lenf:;ths, and no perceptible Interval could be distinguished 

 between giving the stroke and hearing the sound. 

 None Qf these All these experiments are well adapted to show the great 



show the pre- velocity, with which sound is conveved throuph solid bodies, 

 cise vf.loLity . o ^ 



in solid?. but they were made on lengths not sufficient to afford 9 



measure of this velocity, or even to give a precise idea of it, 

 Attempt to A" ingenious pliilosoplier, whom we have now the pleasure 

 asce-tain it by of havhng at Paris, Mr. Chladni, author of some very fine 

 tions " ^^' experiments on the x'ibrations of solids, has proposed u 

 method of estimating the transmission of sound through 

 their substance. It consists in causing a rod of any sub- 

 stance, of a given length, to vibrate by friction: when the 

 tone produced by the ri»d, compared wiih that of a column 

 of air of the same length, will o- ve the ratio of the velocities 

 of the transmission of sound through air, and through the 

 substance of which the r^d is formed. In fact, we readily 

 perceive front the theory, that the velocity of the longitu-, 

 diual oscillations of a body and that of the sounc} trans- 

 mitted through it are proportional to one another: but it is 

 neceisury to be certain, that the whole rod vibrates so as to 

 give hi fundameiital note, vyithout dividing itself into its 

 aliquot parts: forsuch a sepa.ration, heightening proportion-, 

 ally the tone, would give a velocity of sound proportionally 

 15 or 17 times above the truth. In this way Mr. Chladni found, that the 

 as great asm velocity of sound in certain solid bodies is iG or 17 times 

 a« great as in air* The most elastic substances are iron, 

 and fir with very straight fibres, vyhea it is rubbed longitu- 

 dinally. 

 Experiments The construction of the jiqueducts and conduits, which 

 aqueducts ^^ ^^ present c?irrying on for the embellishment of the.capi- 

 fjrnsing at tal,.h^s furnished me with means of making experiments 

 ""** of this kind on a mijch greater length, than any of those 



who have gone before me have had at their disposal. Ttwas 

 besides a subject of curiosity, to learn the effects aud reac^i 

 cf the human voice in very long cylindrical tubes. Such 



were 



