532 



BESSEL OX BAROMETRICAL 



V = 0-78605 

 v, = 0-21325 

 Vi, = 0-00070 



d = 0-9711 

 di = 1-1048 



in 



d„ = 1-5260 



If the relation of P' to P has been obtained by observation, 

 and if the U proportionate to the ditference of elevation be 

 sought, this table shows that, according to Dalton's views, it 

 will be found somewhat gi'eater than according to the older sup- 

 position, and in a proportion given by the table, the numbers of 

 which progress nearly as the square of the argument. If we are 

 W'illing to be content with an approximation which scarcely dif- 

 fers from the truth in all cases of probable occurrence, we may 

 develope (14.) further. We have 



P 



U = log p + log vl/ ; 



and if for log 4/ we w rite the first member of its development, or 

 -^ 1 1' (1 - df + r, (1 - cf^)2 + r„ (1 - d,^"^ = U^ . 0-003675, 

 and for U, its expression. 



H'-H 



= l0£ 



V(i 



II' -H 



0-003675. 



/'(l +;tT) "'"*■ F ' \/'(l +/tT) 



The alteration which the adoption of Dalton's view of the con- 

 stitution of the atmosphere produces in the values of H' — H 

 calculated on the older supposition, is therefore 

 (H' - H)2 



and if H' — H = « . 1000 toises 



«^ 0^-391 , , 



= + -TTTr (15-) 



This difference is much too small for us to hope to obtain by 

 barometrical measurements a decision for or against the reason- 



