PRt)PAGAflON or SOUND. 129 



Whatever thefe refults may prove, as the experiments on 

 the velocily and propagation of ("oiind have been hitherto made 

 in the air alone^ it was an rntcreding enquiry to determine the 

 velocity of found, when tranfmiltcd by other bodies, and par- 

 ticularly of different denfities with refpeft to air. Mr. La- 

 place, to whom branches of phyfical fcience are indebted for 

 improvement, invited me about eight months ago to make 

 experiments on this fubjeclj and particularly on the propaga- 

 tion of found through folid bodies; and the experiments of 

 which I fliall give an account in this paper were principally 

 made in confequence of that gentleman's fuggeftion. 



Making experiments in the quarries beneath Paris oft the Experimints onf 

 tranfmiffion of found through long galleries, I caufed a perfon ^J^J^'^^^"/^^^^^^^ 

 to (Irike with a hammer again ft a mafs of ftone, retiring at the the ftone in 

 fame time by degrees from th^ place of ftriking, in order to<l"^f"es. 

 diftinguifti if poffible the found tranfmitted by the (lone from 

 that tranfmitted through the air.^ Placing my ear againft the 

 mafs of calcareous ftone through which thefe galleries are car- 

 ried, at a ftiortdiftance I diftinguiftied two founds perfe611y fe- 

 parate, one tranfmitted by the air, the other by the ftone. 

 Both founds grew weaker in proportion as I retired from the 

 flriking point ; but that tranfmitted by the ftone was weakened 

 much more rapidly than that tranfmitted through the air. In It was conveye<f 

 a gallery excavated beneath Rue de la Harpe the found tranf- ^''""^Y^^ ^ 

 mitted by the ftone ceafed to be audible at 134< paces diftance; paces j 

 and in a gallery beneath Rue de St. Jaques at 140 paces.-^^--. —^^^ through 

 Through the air the found was tranfmitted to 400 or 440 paces the air 440. 



diftance. The found tranfmitted by the ftone always reached ^J P^^« quickeft 



,r . I r-iii • through the 



the ear much looner than that tranfmitted by the air. ftone. 



Mr. Berthollet, to whom Mr. Laplace imparted thefe re- Ejtperiment re- 

 fults, defirous of being alTured v^'heiher the found of a hammer peated, and 

 could be tranfmitted through a mafs of ftone 140 paces thick, 

 requefted Mr. Gay, by my defire, to be prefent at my expe- 

 riments. With this young chemift i' repeated the experiment the found con- 

 of the tranfmifiron of found through ftone on feveral feparate '^^y*^'^ 150 paces, 

 matfes, and lie convinced himfelf, that found was capable of 

 being tranfmitted through a mafs 150 paces in length. 



It was long ago obferved in working mines, that the noife The propagation 



was propagated to a very great diftanCe through maffes of°^'°""'^ ^^''^"sh 



1 . , ,• r , ; ., ■ , , . o r ftone bng ago 



rock ; and the line of the louna heard through the none lerve'S obferved bymd- 



on many occafions to determine the dire(5lion in which the gal-cbanics. 

 Vol. XI.— June, 1805. K i«Fi9$ 



