and on Astronomical Refractions. 277 



p - -76568 = 30-75 = 266'67 



'=-4905 0' = 10-50 + 0' = 277-17 



a 



" = -3339 0"= - 7'00 + 0" = 259-67 



a 



I find 



(Y-i (0"- 

 \ p 1 



- [0-2988164]. 



The quantity between brackets being the logarithm of the corre- 

 sponding number 



/3 = -32931 y = 1*4910 



E 



= -1-1618 H= -53772 



r = 



in the centigrade scale, the pressure corresponding to *76568 m of 

 mercury in the barometer being unity. In Fahrenheit's scale, 



o 



^ 



-32931 + M618 



the pressure corresponding to 30- 14 inches of mercury being unity. 

 If we take y = 1*5, assuming the 21st observation of M. Gay 

 Lussac, E = 1-1920. 



The difference in the results obtained with these constants from 

 those obtained with the other system of constants y = 1-4910 and 

 E = 1*1618, is quite insignificant, only changing the density 

 slightly in the fifth place of decimals. By taking y = 1-5 



so that the expression for the density becomes more simple, con- 



sisting of only three terms, c~ U 9 c~ ", c~ u t (as will be seen here- 

 after), which is advantageous in the theory of astronomical refrac- 

 tions. 



