BAROMETRICAL MEASUREMENT OF HEIfiHTS. 



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 7 = 0.00120 



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



log (H' H) = 3.31495 



H' H = 2065.1 metres. 



In Table IV. 



= 4- 0.9 



h' 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 = 568.03 millimetres 

 T = + 7.6 Centigrade 

 a = 0.59 



log B = 9.75437 



log B' = 9.62766 



log B log B' = 0.12671 



B' = 424.29 millimetres 



T ' = 9.l Centig. r + r' = 1.5 



a' = 0.57 a + a'= 1.16 



log VBB' = 9.6910 



Table I. log W = 6.9183 



log (a + a') = 



(a -f- a') <yy __ 



lo S v/BB' 

 9.10281 



0.0648 

 7.2921 



4.26483 

 0.00087 



log [log B log B'] = 



In Table I. argt. 1.5, log V = 



In Table II. argt. 7.2921, log V = 



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



log (H' H) = 3.36847 



H' H = 2336.0 metres. 



II' 2 



In Table IV. 



with argument 4800 -|- - - = -|- 3.6 



H 2 



0.9 



with argument 2473 -- = 



h' h = 2338.7 



St. Bernard altitude, h = 2473.0 



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



77 



