BAROMETRICAL MEASUREMENT OF HEIGHTS. 



415 



log [log B log B'] = 9.04215 



In Table I. argt. r + r 1 = + 7.08, log V = 4.27164 



In Table II. argt. 7.4409, log V' = 0.00120 



In Table 111. argt. 46, log G' = 0.00004 



log (H' H) = 3.31495 



H' H= 2065.1 metres. 



In Table IV. = + 

 a a 



0.9 



U __ h = 2066.0 

 Geneva altitude h = 407.0 

 St. Bernard above the level of the sea h' = 2473.0 metres. 



Example 2. 



Computing the height of Mont Blanc from the observations of Bravais and Martins, 

 on the 29th of August, 1844, taking St. Bernard (2473.0 metres) as the lower sta- 

 tion. The observation gives, 



B' = 424.29 millimetres 



r' = 9.l Centig. r + r 1 = 1.5 



a' = 0.57 a + a' 1.16 



log B = 9.75437 

 log B' = 9.62766 

 log B log B' = 0.12671 



B = 568.03 millimetres 

 r + 7. 6 Centigrade 

 a = 0.59 



log 



log*/BB' = 9.6910 

 Table I. log W = 6.9183 

 log (a + a') = 0.0648 



( a 4- a/ ) w - 

 V/BB' ' 



7.2921 



log [log B log B'] = 9.10281 



In Table I. argt. 1.5, log V = 4.26483 



In Table II. argt. 7.2921, log V = 0.00087 



In Table 111. argt. 46, log G' = 0.00004 



log (H' H) = 3.36847 



H' H = 



H' 2 



In Table IV. 



with argument 4800 -|- - = -|- 



TT2 



with argument 2473 



2336.0 metres. 

 3.6 



0.9 



2338.7 



St. Bernard altitude, h = 2473.0 



Mont Blanc above the sea, h' = 4811.7 metres. 



D 



75 



