124 CAUSES which affeft the ACCURACT 



tween I and . n is a number fuch, that the denfity of air 



is as the power i+n of the compreffing force ; it is fuppofed 

 = .0015. 



THE heights of the mercury in the barometers, at the lower 

 and upper ftations, are b and (3 ; H and h are the temperatures, 

 marked by FAHRENHEIT'S thermometer at thofe ftations re- 



fpectively, and- r is put = /. 



39. THEN, the firft approximation to the height, without 



b 



any correction, is, z piog.-. 



$ 



imo. The firft correction, M. DE Luc's, ( 17.) 

 /H+h b 



zdo. THE correction for the decreafe of heat in the fuperior 

 ftrata of the atmofphere, and for the firft inequality of ex- 

 panfion, ( 19.) = 



H+b r(rHh} H^+^Hb+h 2 \ b 



4 



ia 



3//o. THE correction for the fecond inequality of expanfion, 

 or for its variation by a given change of temperature, according 



um/H+b s b bQ 



to the prefTure, ( 22.) : + ( - -- r) plog. x %. j 



or, if E be put for M. DE Luc's, or the firft equation, this laft 

 + - - log . - . But as i* does not appear to be very fmall, 



ft. n 



it will be more accurate to compute ^ - * , which in- 



fffy 



eludes in it both the firft and third corrections ( 21.). 



4/r. 



