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. Feuillee, in 1724 . . * 2213 



the same result modified by Bouguer 2062 



Heberden and Cross, five operations, in 1752 . 2408 



Hernandez, in 1742 . . . . 2658 



Borda and PingrS, in 1771 . . . 1742 



Borda, in 1776 . . . . 1905 



b) made under sail. 



Mannevilette, in 1749 .... 2000 



Borda and PingrS, in 1771 . . 1701 



Churruca, in 1788 .... 2193 



Johnstone, . . . . 2023 



2. Barometric measurements calculated after the formul a 



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 toises j and, what is remarkable enough, the results 

 obtained by geometrical operations differ more from each 



Ingleses, 1731 toises 5 summit of the Peak, 3287 toises." I 

 cannot guess what Mr. O'Donnell calls Spanish toises 5 for 

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

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

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

 three measurements. 



