148 



two stations at fifteen and twenty degrees of Reaumur's ther- 

 mometer^ I obtain by Laplace's method, three hundred and 

 thirteen toises for the town of Laguna. This height would 

 be augmented only sixty-six toises, or one-fifth, if 28 inches 

 3 lines were taken for the mean height of the column of mer- 

 cury at the port of Orofava ; though it is well known, that 

 P. FeuilleVs barometer, by no means well freed from air, 

 was constantly six or eight lines, or even more, too low*. 

 Mr. Lichtenstein, who has made an interesting journey into 

 the interior of Africa, reckons the absolute height of La- 

 guna two or three thousand feet above the level of the 

 coasts f . 



Andanson, in his voyage to Senegal J, states, "'that' the 

 elevation of the Peak of Teyde (in 1749) was found to be 

 more than two thousand toises." It is probable that this re- 

 sult was founded on a base measured by the log, and on an 

 operation made under sail by Mr. Dapres de Mannevilette, 

 commander of the vessel of Which Andanson was on board. 



Dr. Heberden §, in the narrative of his excursion to the 

 top of the Peak in 1752, says he found the absolute eleva- 

 tion of the volcano to be 15396 English feet, or 2408 toises. 

 <( This result," adds he, " has been confirmed by two other 

 operations, which I have successively executed : it is also 

 entirely conformable to the results of two trigonometrical 

 operations made long before by Mr. John Cross, English 

 Consul at Santa Cruz in TenerifFe." Here are fivemeasure- 



* Feuillee's barometer at the top of the Peak, 17 inches 

 5 lines. Borda's barometer at the same point, 18 inches 

 0 lines. Lamanon's barometer, 18 inches 4 lines. 



f Allgem. Geog. Ephemer. 1806, p. 51. 



% Vol. i, p. 8. 



§ Phil. Trans, vol. xlvii, p. 353. Cook's second Voyage 

 round the World, vol. ii, p. 282. Barrow, Voyage a la 

 Cochin Chine, t. 1, p 69, 



