r 460 ] 



for that was owing to accidental caufes, viz. the heat of the 

 tent in which it flood, and that of the man that carried it, 

 and not having been allowed time to cool. 



2do. 2831,3 feet converted into fathoms = 471,833 fathoms. 



Log. of 28,390 = 4531 >654 

 Subftra(ft the fathoms — 471,833 



Remainder = 4059,821 

 which is the logarithm of the height of the mercury in the upper 

 barometer, and denotes the natural number and height of the 

 mercury = 25,467 inches nearly. 



But this height is that which the mercury would have in the 

 temperattire of 32°, and the temperature being 64^ this height 

 muft be increafed by ^^-5-- part multiplied into the fundamental 



difterence, which in this cafe is 32". Now -2 l-i ^ ,00265, 



9600 



which multiplied into 32° gives ,0901, and this added to the 

 mercurial height 25,467 gives 25,557, its true height at tem- 

 perature 64'^. 



In this manner the barometrical heights at the altitudes of the 

 line of congelation may be found. Thus the altitude of the 

 line of congelalion, latitude o being 28000 = 4666,66 fathom, 



if 



