BAROMETRirAt, MEASUREMENT OF HEIGHTS. 



log [log B — log B'] = 



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



In Table II. argt. 7.4409, log V = 



In Table III. argt. 46°, log G' = - 



log (H' - H) = 



H' 



In Table IV. — - 

 a 



h' 



9.04215 

 4.27164 

 0.00120 

 0.00004 

 3.31495 



- H = 2065.1 metres. 



IP 



- = + 0.9 



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 



log [log B — log B'] = 



In Table I. argt. — 1°.5, log V = 



In Table II. argt. 7.2921, log V = 



In Table 111. argt. 46°, log G' = — 0.000^ 



log (H' — H) = 3.36847 



In Table IV. 



B' = 424.29 millimetres 



t' = — 9°.l Centig. T + r' = — 1°.5 



a' = 0.57 a-i-a' = 1.16 



logVBB' = — 9.6910 



D 



77 



