and on Astronomical Refractions. 277 



p = -76568 





= 30°-75 





— = 266*67 



p' = -4-905 





6' = 10°'50 





— + 0' = 277*17 



f- -3339 





0" = - 7°'00 





— + 0" = 259-67 



I find 



<&■: 



-i ( 9 "-0)(~ 



+ 



') 



(5-)'- <•■-•) (£+') 



= [0-2988164]. 



The quantity between brackets being the logarithm of the corre- 

 sponding number 



/3 = — -32931 y = 1-4910 



A = F^l 



= -1-1618 H= -53772 



_jg^ 081857] _, 266 o. 67 



^-•32931 + 1.1618 



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

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



[3-0634582] 

 ^-•32931 + 1-1618 ' 



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~ 3w , c~~ 2w , c~ u 9 (as will be seen here- 

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

 tions. 



