BAROMETRICAL MEASUREMENT OF HEIGHTS. 



Table I. gives the corresponding numbers, 



Difference, 



Table II. gives for T' T, 



JL. 2 (t + t>) = 1.897 X 93.2, 



Table III. gives for mean latitude of 21, 



Difference, 

 Sum, 



h = 8183.5 

 h' = 6280.8 



1902.7 

 5.2 



1897.5 = N 

 + 176.8 



2074.3 



+ 4.3 

 Table IV. gives for decrease of gravitation in the vertical line, -|- 6.0 



Hence altitude of Guanaxuato above the ocean, 2084.6 



Measurement of the height of Mont Blanc, August 29, 1844. By MM. Bravais 



and Martins. 



mm. Q o 



Barometer at one metre below the summit, h' = 424.05 T' = 4.2 t' = 7.6 

 Barometer of the Observatory of Geneva, h = 729.65 T == 18.6 t = 19.3 



Hence elevation of upper barometer above the ocean, 4813.5 



Finally, height of the summit of Mont Blanc above the ocean, 4814.5 



D 



16 





