159 



Let us now resume the barometrical and geometrical mea- 

 surements of the Peak made for a century past. 



1. Geometrical measurements. 

 a) made on land. 



toises 



P. Feuillfce, in 1724 . . , 2213 



the same result modified by Bouguer 2062 



Heberden and Cross, five operations, in 1752 . 2408 



Hernandez, in 1742 .... 2658 



Borda and Pingr£, in 1771 . . . 1742 



Borda, in 1776 ..... 1905 



b) made under sail. 



Mannevilette, in 1749 .... 2000 



Borda and Pingr£, in 1771 . . . 1701 



Churruca, in 1788 .... 2193 



Johnstone, ^ 2023 



2. Barometric measurements calculated after the formula 

 of La Place. 



toises 



Feuillee and Verguin, in 1724 . . . 2025 



Borda, in 1776 ..... 1976 

 Lamanon, in 1785 . . . 1902 



Cordier, in 1803 .... 1920 



These measures, taken at different periods, vary from 1700 

 to 2600 toiseg and, what is remarkable enough, the results 

 obtained by geometrical operations differ more from each 



Ingleses, 1731 toises j summit of the Peak, 3287 toises." I 

 cannot guess what Mr. O'DonnelJ. calls Spanish toises j for 

 supposing him to mean the vara casteliana, 2*23 of which 

 make a French toise, the volcano would be much less ele- 

 vated than Mr. de Borda found it, even it]L the first of his 

 three measurements. 



