150 



angle, minuted in the register as being thirty-three minutes, 

 while it was in reality found to be fifty-three minutes." 



The result of the trigonometrical measurement made in 

 1 776 is 1905 toises : it is this which is now most generally 

 adopted, and on which is in great part founded the position 

 cf the Canary Islands, in Varela and de Borda's charts. 

 I trust, that I shall render a service to naturalists, philoso- 

 phers, and navigators, in here recording the detail of the 

 operations made during the voyage of the frigate la Boussole, 

 and taken from the valuable manuscript which I mentioned 

 in the preceding chapter *. It were to be wished, that Mr. 

 de Borda's Journal was published entire. The results it 

 contains are found in the Carte particuliere des Isles Cana- 

 ries, d'apres les Observations de la Bousoleet de VEspiigle, 1776. 

 This chart, the best of all that have hitherto appeared, 

 forms a part of the collection published by the Depot of the 

 Marine, at Paris. 



te The measurement of the Peak of Teneriffe," says Mr. de 

 Borda, " was not an object of mere curiosity, but was essen- 

 tially connected with our nautical labors. It was necessary 

 for us to know the exact height of this volcano, in order to 

 avail ourselves of the observations of apparent height which 

 we had made at several points of the island of Teneriffe, Go- 

 mera f, and Canary, and which were to serve for ascertain- 

 ing the longitudes and latitudes of those points. 



* Vol. i, p. 142. The manuscript of the Dep6t is 190 

 pages in 4to ; it was copied from the original, by Mr. de 

 Fleurieu. I am indebted for the communication of it to the 

 kindness of Vice-admiral Rosily. 



+ At the port of Gomera, for instance, Mr. de Borda 

 found the angle of altitude of the Peak 4° l 1 . An azimuth 

 placed the mountain east 24° 17 1 north. Supposing it's ele- 

 vation above the level of the ocean 1904 toises, we find the 

 port of Gomera distant from the Peak 0° 27' 18". 



