510 



that the ocean is feebly illuminated at thirty or 

 forty leagues distance ; or that the strata of 

 air nearest the Earth may extinguish a great 

 deal of the light, by absorbing the rays that 

 traverse them. 



Even supposing the effects of refraction * not 

 to exist, the islands of Tortuga, Orchila, Roques, 

 and Aves, the nearest of which are twenty- 

 five leagues distant, ought to be visible in fine 

 weather from the top of the Silla. We per- 

 ceived none of these islands; either because 

 the state of the atmosphere was not favourable, 

 or because the time we could employ in looking 

 for them while the sky was serene was not 

 sufficiently long. A well informed pilot, who had 

 attempted to climb with us to the top of the 

 mountain, Don Miguel Areehe, assured us, 

 that he had seen the Silla from the sea near 

 the Cayes de Sal, at the Rocca de Fuera, in the 

 latitude of 12° l'-f-. If the surrounding moun- 

 tains did not intercept the view, the coast to 

 the east as far as the Morro de Piritoo, and to 

 the west as far as the Punta del Soldado, ten 

 leagues to leeward of Porto Cabello, ought to 

 be visible from the summit of the Silla. To- 

 ward the south, within the land, the range of 



* The visual ray without refraction makes an angle of 

 1° 89'; with a refraction of one tenth, it is 1° 50 '. 



+ The latitude of the Silla is 10° 31' 5", according to 

 iMr. Ferrer. 



