[ 44° } 



in the upper barometer differs from its height in the lower ba- 

 rometer. The weight of the intermediate column of air is 

 juft equal to the weight of that number of inches, or parts of 

 an inch of mercury. Now a cubic inch of mercury, tempera- 

 tore 32^, weighs 3443,2 grains ; therefore if the mercury in the 

 upper barometer has fallen a inches, or parts of an inch, the 

 intermediate column will weigh 3443,2 «■ Thus if the mer- 

 cury has fallen only Jj. of an inch, the weight of the interme- 

 diate column of air is 3443,2 x 0,1 = 344)32 grains. 



Problem, IV. 



The elevation being given, and the height of the mercury 

 above and below being found, to find whether the mean tem- 

 perature of the intermediate column of air were above or 

 below 32° or at 32^ exadlly. 



Solution. 



I F the number of fathoms in the elevation cxaHly correfponds 

 with the difference of the logarithm of the mercurial heights 

 then the mean temperature of the column was exadlly 32". If 

 the number of fathoms in the elevation exceeds the number 



indicated 



