804 



not white, but displayed the most beautiful co- 

 lours of the rainbow, while the interior of the 

 halo, and the whole vault of the sky was azure, 

 without any trace of visible vapors. 



We began to lose sight of the island of Mar- 

 guerita^ and I endeavoured to verify the height 

 of the rocky groupe of Macanao. It appeared un- 

 der an angle of 0° 16' 35"; which, in a distance es- 

 timated at sixty miles, would give the groupe of 

 mica-slate of Macanao the elevation of about 660 

 toises, a result $j which, in a zone where the ter- 

 restrial refractions are so constant, leads me to 

 think that the island was less distant than we 

 supposed. The dome of the Silla of Caraccas, 

 remaining 62° S.W. long drew our attention. 

 We contemplate with pleasure the summit of a 

 lofty mountain which we have climbed with 

 danger, and which sinks gradually below the 

 horizon. When the coast is not loaded with 

 vapours, the Silla must be visible at sea, without 

 counting the effects of refraction, at thirty- 

 three leagues distance During that day, 

 and the three following days, the sea was co- 

 vered with a bluish skin, which, examined by a 

 compound microscope, appeared formed of an 

 innumerable quantity of filaments. We fre- 

 quently find these filaments in the Gulf-stream, 



* Vol. ii, p. 45 ; Vol. vi, p. 498. 

 f Vol, iii, p. 506. 



