Barometer applied to the Measurement of Heights. 367 



the air being 45 ; and at the upper station, the height of the 

 barometer was 25,19, its temperature 46, and that of the air 39, 

 the latitude of the place being 30. 



In this case, we have 

 T T'=50 4b=4* ; - 

 and 



31= 



cos 2 L = cos 2 X 30 = cos 60 = J, 



Whence 



w = 29 4 log. 



wF 25,2003 log. 



11 



0,00223 . 



1st correction 



\ 0,002837 

 2d correction 



R = 3481280 



- = 0,0002 



R 



_ ) = 1,0004 



3d correction 



1,46835 

 1,40141 



669,4 log.. . 3,82569 

 log.. . 1,04139 

 log.. . 3,34830 



16,42 log.. . 2,21538 



685,82 log.. . 2,83621 

 log.. . 3,15168 



0,97 log.. . 1,98789 



686,79 log.. . 2,83682 

 log.. . 6.54174 



log.. . 4,29508 



. 2 log... 0.00034 



3,4 

 690,19 fathoms. 



Laplace's formula, applied to the same example, gives 683,97 

 fathoms, differing from the above only 1,22; whereas, by Sir 

 George Shuckburgh's method, in which no account is taken of the 

 variation of gravity, either for difference of latitude or difference 

 of elevation in the same latitude, the result is 685,125. This 

 corre>ponds with the approximate height derived from the first 

 correction in the above example. 



