Of BAROMETRICAL MEASUREMENTS. 117 



/ a n\ 



, H+h \l q q\ 



from it, viz. % = ?(i+ OT ( r JJ ~ I , in all the 



\|3 nb / 



terms of this equation, into which s enters as a divifor, we 

 mall have a new and more accurate value of z, and, by a like 

 procefs, might from thence obtain one ftill more accurate, if 

 it were neceflary. 



Now, if this be done, and if the correction depending on 

 be fuppofed fufEciently determined by the computations of the 

 two preceding articles, fo that it may now be neglected altoge- 

 ther ; and if m alfo be fo fmall, that all the powers of it, higher 

 than the firft, may be neglected, we obtain, 



,H+b x\ , b 



.\ . p, ,H+ b ^\, 



)J log + JL^ +m (Z. -- r)J log. 



32. THE firft term of the preceding equation is the height 

 corrected by M. DE Luc's method ; the fecond term, viz. 



2p 3 / H+h * b 



[i+m( --- r)\ log. , is the correction for the diminu- 



S 2 / p 



tion of the weight of the quickfilver in the uppermoft barome- 

 ter j and the third term, or ( I + m ( -- >")) ( lo '~& 



the correction for the gradual diminution of the weight of the 

 air in the different ftrata between the lower and the upper fta- 

 ftion. The laft of thefe two corrections, which, in all ordinary 

 cafes, is alfo the lead, is the only one of them to which, it would 

 feem, that any attention has hitherto been paid. The other, or the 

 effect of the diminution of the gravity of the quickfilver, was 

 included in this inveftigation, when, at 25. we fubftituted for 



y, 



