404 



hitherto very little employed, on reducing the 

 heights of the Sun to the same time, a reflecting 

 instrument may be used like an instrument 

 furnished with a level. I found the latitude of 

 the Cape, which is not marked on the maps of 

 the Deposito Hydrografico of Madrid, in other 

 respects so exact, to be 10° 36' 45" ; I could 

 only make use of the angles which gave the 

 image of the Sun reflected on a plane glass ; 

 the horizon of the sea was very misty, and the 

 windings of the coast prevented me from taking 

 the height of the Sun on that horizon. 



The environs of Cape Blanco are not unin- 

 teresting for the study of rocks. The gneiss 

 here passes to the state of mica-slate*, and 

 contains, along the seacoast, layers of schis- 

 tose chlorite \. In this latter I found garnets 

 and magnetical sand. On the road to Catia we 

 see the chloritic schistus passing into horn- 

 blende schistus^. All these formations are 

 found together in the primitive mountains of 

 the Old World, especially in the north of Eu- 

 rope. The sea at the foot of Cape Blanco throws 

 up on the beach rolled fragments of a rock, 



(Obs. Ast. y Tom. i, p. 192.) Jefferys, in the West India Pilot, 

 1783, places Cape Blanco twenty minutes, or almost seven 

 leagues, west from JLa Guayra. 



* Glimmerschiefer . 



\ Chloritschiefer . 



% Hornblendsehiefer. 



\ 



