344 



the Cordilleras. This declivity is poor in mines^ 

 particularly in mines anciently worked ; it is 

 almost entirely composed of volcanic rocks in 

 the provinces of Popayan, Pasto, and Quito. 

 The gold of Guyana probably came from the 

 country east of the Andes. In our days a lump 

 of gold has been found in a ravine near the 

 mission of Encaramada, and we must not 

 be surprised, if, since the Europeans settled 

 themselves in these wild spots, we hear less of 

 the plates of gold, gold dust, and amulets of 

 jade, which could heretofore be obtained from 

 the Caribbee and other wandering nations by 

 barter. The precious metals were never very 

 abundant on the banks of the Oroonoko, the 

 Rio Neg'ro, and the Amazon ; and disappeared 

 almost entirely when the system of the missions 

 caused the distant communications between the 

 natives to cease. 



The climate of the Upper Guainia is less hot, 

 and perhaps somewhat less humid, than the 

 climate of the banks of the Tuamini. I found 

 the temperature of the water of the Rio Negro, 

 in the month of May* at 23*9° ; the air being 

 by day 227°, and at night 218° of the centi- 

 grade thermometer^ . This coolness of the wa- 



* 19*2° Reaumur, or 75° Fahrenheit. 

 + The following is a statement of the observations, which 

 I made at San Carlos del Rio Negro, the sky being con- 



