Geological Obf creations. jSr 



p d added to the approximate height, if the 

 mean temperature be above 3i?,24, or fub- 

 ftra&ed from that height, if the mean tem- 

 perature be below 31,24 gives the true height. 



The following example will make the cal- 

 culation more intelligible, the inftruments on 

 the top of the mountain are denoted by A 9 

 and thofe at the bottom by B. 



OBSERVATIONS. 



Barometer A - 2 5> T 9 Inches. 



Its attached thermometer 46? 



Detached thermometer A 39,5 



Barometer B at the fame time 29,4 

 Attached thermometer - 50 

 Detached ditto - - 45? 



CALCULATION. 



Here the lower barometer ftands below 30 

 inches, and its attached thermometer below 

 55? namely at 50. then 72 = 5 and ,00304x5 

 = ,01520 this would be the correction to be 

 added if the barometer were at 30, but as it 

 is at 29,4 then 

 b_c_, 29,4 x, 01520^,44688 _ g 



3 " 3 3 



which 



