[ 462 ] 



ive:gbt of the intermediate column of air, on a bafis of one 

 fquare inch, let the temperature be what it may. 



Solution. 



This Is found as in p. 439, and thus the weight of a column 

 of air of any elevation and temperature, and under any given 

 preflion, may be known, firft determining the height or number 

 of inches at which xnercury would ftand on that elevation by 

 the laft problem. 



Thus the weight of the intermediate column of air at Saleve, 



the barometer below being at 28,39 ^"'^, above, at 25,486, was 



28.390—25,486 = 2,90+ inches of mercury = 3443>2 grains 



X 2,904 — 9999,0528 grains or 20,8 fo troy ounces ; whereas, the 



weight at the mean temperature of 3 a*' would have , be&n 



28,390 — 25,467 = 2:923 inches of mei'Gury = 20V9JS7 troy ounces. 



_; K) v3Hj (V/oIad 3/igiirl it.:nno..: 

 JSlote. The weight of a vertical column o£ air of a given 



length cannot be determined, unlefs the weight to which it is 

 fubjed be known, and confequently the height at which mer- 

 cury would {land in a barometer placed over it be alfo known ; 

 now this weight is variable according to the ftate of the baro- 

 meter below, though the temperature fhould be conftant. 



Tnt/s 



