SUPPOSED MIWEBAL BICHEB. 341 



The astronomical observations made in the n.ght of the 

 25th of April did not give me the latitude with satisfactory 

 precision. The latitude of the mission of San Fernando 

 appeared to me to be 4 2' 48". In Father Caulin's map, 

 founded on the observations of Solano made in 1756, it is 

 4 1'. This agreement proves the justness of a result which, 

 however, I could only deduce from altitudes considerably 

 distant from the meridian. A good observation of the stars 

 at Guapasoso gave me 4 2' for San Fernando de Atabapo. 

 I was able to fix the longitude with much more precision 

 in my way to the Rio Negro, and in returning from that 

 river. It is 70 30' 46" (or 4 0' west of the meridian of 

 Cumana). 



On the 26th of April we advanced only two or three 

 leagues, and passed the night on a rock near the Indian 

 plantations or conucos of Guapasoso. The river losing itself 

 by its inundations in the forests, and its real banks being 

 unseen, the traveller can venture to land only where a rock 

 or a small table-land rises above the water. The granite 

 of those countries, owing to the position of the thin 

 laminae of black mica, sometimes resembles graphic granite ; 

 but most frequently (and this determines the age of its for- 

 mation) it passes into a real gneiss. Its beds, very regularly 

 stratified, run from south-west to north-east, as in the Cor- 

 dillera on the shore of Caracas. The dip of the granite- 

 gneiss is 70 north-west. It is traversed by an infinite 

 number of veins of quartz, which are singularly transparent, 

 and three or four, and sometimes fifteen inches thick. I 

 found no cavity (druse), no crystallized substance, not even 

 rock-crystal ; and no trace of pyrites, or any other metallic 

 substance. I enter into these particulars on account of the 

 chimerical ideas that have been spread ever since the six* 

 teenth century, after the voyages of Berreo and Raleigh,* 

 " on the immense riches of the great and fine empire of 

 Guiana." 



The river Atabapo presents throughout a peculiar aspect ; 

 you see nothing of its real banks formed by flat lands eight 



* Raleigh's work bears the high sounding title of " The Discovery of 

 the large, rich, and beautiful Empire of Guiana." (Land. 1596.) Sec 

 also Raleghi admiranda Degcriptio Regni Guianae, auri abundantis&iaoi 

 (Homlius, Noriberya, 1599.) 



