78 



deira is 5162 English feet, or 807 toises. The 

 small Desert Islands and the Salvage, on which 

 are gathered the archil and the mesembryan- 

 thenium crystallinum, are only 200 toises in per- 

 pendicular height. I think it useful to fix the 

 attention of navigators on these measures, be- 

 cause, according to a method of which this nar- 

 rative offers several examples, and which Borda, 

 Lord Mulgrave, Mr. de Rossel, and Don Cosmo 

 Churruca have successfully employed in their 

 expeditions, we may, by angles of height taken 

 with good reflecting instruments, discover with 

 sufficient exactness the distance, at which a 

 vessel finds itself from a cape, or an island with 

 mountains. 



When we were forty leagues east of the island 

 of Madeira, a common swallow came and perched 

 on the topsail-yard. It was so fatigued, that it 

 suffered itself to be easilv taken. What could 

 engage a bird, in that season, and in calm wea- 

 ther, to fly so far ? In the expedition of d'Entre- 

 casteaux, a common swallow was seen at 60 

 leagues distance from Cape Blanc ; but this was 

 towards the end of October, and Mr. Labillar- 

 diere thought it had newly arrived from Europe. 

 We crossed these latitudes in June, at a period 

 when the seas had not for a long time been agi- 

 tated by tempests. I dwell on this last circum- 

 stance, because small birds, and even butterflies, 

 are sometimes forced out to sea by the impetu- 



