84 



Mr. Nixon on Utt Theory of the 



[Aug. 

 with the 



(Tlie degree of accuracy of the method 



number of the subdivided columns, we may convince ourselves 



by repeated calculations that it is superfluous to divide the 



column into lengths less than one inch.) 



- Example* — Upper barometer 15*5 inches ; lower barometer 



30>5.i^chesr 



Inches. 



r29-5 and 30-5 



t 



.5 



28-5 

 27-5 

 26-5 

 25-5 



"1, 



'O 



"W 



K 



>S ( 



23 



20-5 

 19-5 



15'6. 



29-5 

 28-5 

 27-5 

 26-5 

 25-5 

 24-5 

 23-5 

 22-5 

 21-5 

 20-5 

 19-5' 

 18-5 

 17-5 

 16*5 



Mean 301 

 29 



b 



|'.)i 



28 

 27 

 26 

 25 

 24 

 23 

 22 

 21 

 20 



18' 



-!7 



Feet. 



870-01 

 900-0 

 932-1 

 966-6 

 1003-8 

 1044-0 

 1087-5 



I io 



^l|^- 1134-7 ^-S^ 

 ' - 1186-3' ^ ' 





1242-8 

 1304-9 

 1373-6 

 1450-0 

 1635-2 

 1631'2j 



Feet. 



870-0 



1770-0 



2702-1 



3668-7 



4672-5 



5716-5 



6804-0 



7938-7 



9125-0 



10367-8 



11672-7 



13046-3 



14496-3 



16031-5 



1^17662-7 



(Cori-yct altitude 17666-0 ;''Eti-br — ' 3-3' fe6tl) \ '^' 



Dividing the stratum of air into, any number of sections of 

 equal altitude, we may find by a little further calculation the 

 pressures they sustain, and demonstrate the decreasing geome- 

 tric progression of the latter; for if we take any two consecutive 

 pressures and divide the consequent by the antecedent one, and 

 any other two consecutive pressures be taken and the consequent 

 of these be divided by their antecedent, the two quotients (or 

 ratios), will bei found. to be equal to each other, and less than 

 unity, which^ifi tihe characteristic of. a descending geometrical 

 series. - ■'■■' '"' f^'- .•• .,, ^e^t.'fj'i" '> 



Example. no'i^Bluols^B.iyr' 



PresKurefat^the base I . 



at an altitude of 



Feet. 



4416-5 



8833-() 



13249-5 



17^66-0 



>0-5000*i><qikd^i(irjili$ §| istpios. 



25-7518 

 21-7428 

 18-3579 

 15'5000,> 



-84432 



Having found the altitude of the objeck/the tfeiiijiefature of the 

 air being 32°,, let u^ qpw suppose t^e temperature tp hare been 

 80°, or 48 degrees abov-^ the freezing pmntl''*'1aiWv)?pV me of the 



dry air is consi»quentIy increased 



j48 

 4H0^ 



ory^th, 



and its density, in- 



