-n«o?»\o ^^^'^jrttiisfnitted through Liquids. ''^ ' "^ 321 



cYqSp.B^ ' ds^ de 

 </2S 1 V, </2s 



=0, 



.w./lm0OToriq.- ^^ ^^ y^ ^2 •, q, oOOO' -^avBri 



When the pressure of the atmosphere is callecf ttmt'y, 'We iiav« : 

 c = "0000461 according to (Ersted. Now putting p , the pressure 

 of the atmosphere, p^ the density under that pressure, and A, the 

 height of the column of water which produces the same pressurelr^ 

 we have :...--- '^_ 



Pi=9P\h^, or Pj=^,j1j ni emoitje 80OJ:/3i:tiioo 



. J_ _ ^ _ gh^ ^ oiiiaoq ibxfJ v ^ t» 

 ' ^Pi Qi^i "0000461 ' .jaaotaoBlqeib 



since ^^ =1 — "0000461, we may call the vame unity i 





 To find A, when the barometer is 30 inches and the tempera- ' 



ture 50° Fahrenheit, we have the specific gravity of mereuiV 



13"62, and ,„. , ; , '-^.i,... ■■ . ''■^' ■■■•' .^''^i- uj/bii> 



iwTiom, j/jj '. 30 X 13-62'^«/h 3dJ m ijlflo a^eiq 



n, in feet = ^-^r 



\j =5:34-05. 



Taking 9 =32* 1892 in the latitude of London, we find- viritn^ 

 these 



— =4876"0 feet vgjljocity per second. 



The expression a/ — for "tliie^velbcity of sound in liquids 



coincides with those given by Poisson and Sir John Herschel 

 when brought to the same form. 



The velocity 4876 feet is the theoretical velocity for water 

 deprived of air, and exceeds the velocity found from experiments 

 in the lake of Geneva by Messrs. Colladon and Stuiin. 



In Sir John Herschel's treatise on Sound, it will be found that 

 the theoretical velocity calculated from the data of Colladon and 

 Sturm is 46856 feet per second, whilst the velocity from their 

 experiments was found 4708 feet per second. 



Many more experiments must evidently be tried before the 

 actual velocities of sound in lake and sea water arc accurately 

 determined. 



London. February 27, 1R51. 



a/; 



