PROPACJATION OF SOUND. 13J 



Having convinced myfelf, that the propagation of foand 

 through ftone and tlirough wood was effeded with much 

 greater velocity than through air, and that the time of its Iranf- 

 miflion to fuch fliort diftances as thofe on which I was able to 

 make experiments was too little for calculation, I was delirous 

 of knowing whether the velocity of its tranfmiffion through 

 metallic fubftances were the fame. 



Several experiments on bars of iron fixed on folid mtifTes, as Similar experl- 

 Ihe bars that hold together the ftones of parapets, having; given "^f""^*" •'"'^ re- 



ri T r t c T I .. r r «- • i^hs mth long 



ine uncertain relults, I (ought for ilolated bars of lufficient bars of iron. 

 length to afford fome certainty. My firft experiment was made 

 on the upper bars of an iron railing, 34< paces long, ereded on 

 one of the walls of the garden of the Legiflative Body, ad- 

 joining to the Place des Invalides. On ftriking one extremity 

 of this afTemblage of bars, two diflinft founds were heard at 

 the other end; that tranfmitted by the bars, and that by thd 

 air; the former Ibeing always heard firfi-. The fame experi- 

 ment afterwards repeated on bars of different lengths, gave 

 me the fame refult; and this refult is fuch, that it isimpoflfiBle 

 to diftinguifli, at the fmall diflances at which thefe experi* 

 ments were made, any difference between the tranfmiffion of 

 the motion by light, and that of the found by the folid me- 

 dium. 



Repeating my experiments on the velocity and propagation Mr. Gay fup- 

 of found through the maffes of fione in the quarries beneath P^^ed he heard 



Paris, in company with Mr. Gay, this young chemiftimaginedt-i^oyg^'the air 

 that he diftinguiflied two founds tranfmitted through the air, firft a grave, 

 one grave and the other acute, which reached his ear in fuc-^ °" an acute, 

 ceflion, the graver found appearing to have the greater velo- 

 city. 



This refult, though contrary to the theory of the propagation Malran and 

 of found, according to which grave and acute founds ought "^!?^'^ ^^"^ ^^^* 

 toliave the fame velocity, had already been conjectured by fe-fame. 

 veral philofophers, particularly by Mairan, and was therefore 

 worth confirmation. For this purpofe I llretched two firings, Exneriment to 

 one of brafs, the other of catgut, fo as to make them erait^*^^'^"^"^ ^^*^* 

 two different tones, the firft one more acute, the fecond one 

 more grave ; then ftriking both thefe firings at once with the 

 wood of a black lead pencil, the two founds, which were con- 

 founded together at firft, appeared to feparate at the diftance 

 of 400 paces in a large gallery of the quarries, and we both 

 imagined we could diftinguifti the graver found firft. 



K2 While 



