690 



(Oarony), and the Coari* (Caura), take their 

 rise from the famous lake Cassipa, for which 

 they afterward substituted the Laguna del Do- 

 rado. The current of the Oroonoko diminished 

 in velocity as we advanced. I measured several 

 times a basis along the beach, to ascertain the 

 time which floating bodies took in traversing a 

 known distance. Above Alta Gracia, near the 

 mouth of the Rio Ujape, I had found the velo- 

 city of the Oroonoko 2*3 feet in a second ; be- 

 tween Muitaco andBorbou it was only 1*7 foot. 

 The barometric observations made in the neigh- 

 bouring steppes prove the smallness of the slope 

 of the ground from the longitude of 69° to the 

 eastern coast of Guyana. We found in this coun- 

 try, on the right bank of the Oroonoko, small 

 formations of primitive gruenstein, superim- 

 posed on granite (perhaps even embedded in the 

 rock) . We saw between Muitaco and the island 

 of Ceiba a hill entirely composed of balls with 

 contentric layers ; in which we perceived an in- 

 timate mixture of hornblende and feldspar, with 

 some traces of pyrites. The gruenstein resembles 

 that in the vicinity of Caraccas ; but it was im- 

 possible to ascertain the position of a formation, 

 which appeared to me to be of the same age as 



* The names printed in Italics are the names of the Ami, 

 Carony, and Caura, as disfigured by Raleigh and the geo- 

 graphers Hondius and Sanson, 



