468 



Mr. Lubbock on the Heat of Vapours 



This expression can be integrated, and I find, supposing z = 0, 

 after a proper determination of the constants, 



a 



k (1 + «9) 



{/_/}{l +y } 



*{At+*)-A|+.)} 



Nap. log 





If the variation of the force of gravity be neglected, the pressures 

 p, y maybe represented by the heights of the barometer /z, h'. 

 If M be the modulus or the quantity by which Naperian logarithms 

 must be multiplied to give common logarithms, Laplace makes 



k 

 —tz= 18337 m, 46. log M = 9*6377843. 



gM 



In order to give an example of the use of this expression, I take 

 the 21st observation of Gay Lussac, 



h= -76568 

 h'= -3339 



log 18337*46 



log(l +«0) 



== 30-75 

 6'= - 7-00 



log 





log 



(?+•) 



(0 



log/3 



«y/ 



= 4-2633392 

 = 0-0474015 



= 0-2696699 



= 8-7762776 



3-3566882 

 9-5176049 



3-8390833 

 = 6903-7 



1 + 



log a =6-8041 168 in metres. 

 z' = 6921*7 metres. 



