the Barometric Formulae, Sfc. 



645 



I will now give the proposed modified formula, with its peculiar constant. 



Let z be the required height of one station of observation above the other. 



Let be the mean latitude of the stations of observation. 



Let T, t' be temperatures (Centigrade) of atmosphere given by detached 

 thermometer. 



Let t, <' be temperatures (Fahrenheit) of atmosphere given by detached 

 thermometer. 



Let T, y be temperatures (Centigrade) of quicksilver given by attached 

 thermometer. 



Let 3, 3' be temperatures (Fahrenheit) of quicksilver given by attached 

 thermometer. 



Let p, /3' be observed barometric pressures, not corrected for anything. 



Let H. C. indicate horary corrections. 



Centigrade Formula. 



z = 18490-0 1 1 + 0-002695 . cos 2^! < 



■ + -'1 



1 + 0-004 



and 



T -I- T 



1 + 0-0035 — V 

 ^ J 



"" ^°^ ^'. 1 1+0-00018. (r-r)i-*^^- ^^ 



Fahrenheit Formula. 



1 + 0-002222(^^4^-32 



z = 60664-0 i 1 + 0-002695 . cos 20j < 



and 



1 + 0-002 f^^^- 32 



^ t + t' 



> X 



X log a' 



^ 



|3'. 11+0-0001. (3-3')}- 



:(H.C.). 



The multipliers 0-0035 and 0-002 must be employed in place of 0004 and 

 00022222, &c., whenever the mean temperature of atmosphere, as given by the 

 detached thermometers, may be below the freezing-point ; but I have to remark, 



