6^ N^I'VRAL HISfORT 



'Tides are of the utmofl confequence to the inhabitants of 

 the coaft of Guiana. They enable them to drain a country 

 which otherwife could never have been cleared, and they af- 

 certain their journeys which are made by water up and down 

 the rivers, and even along the coaft. At the mouth of the 

 Demerary, it is high water at about half paft five, at new 

 and full moon. The rife in fpring tides, a little way up, is 

 twelve feet, or more, above low water-mark. The tide runs 

 very rapidly near the mouth of the river, feldom lefs than four 

 or five miles in the hour. It continues to run with force for 

 a long way up, and was fufficient, without wind, to carry us 

 up or down at 150 miles from the mouth. Above that it be- 

 comes feebler ; and for a confiderable diftance below the rapids, 

 though there is a fenfible rife and fall of two or three feet, yet, 

 even in the dry feafon, the current is conftantly down, only 

 more gentle during the rife or flood, and there alfo the conti- 

 nuance of the rife is very fliort, not more than two or three 

 hours. 



Some obfervations upon the Soil of the different parts of 

 the country, may be the fubjedl of a future communication. 

 I will only add at prefent, what I think has more than con- 

 je(5lural foundation, viz. That this moft recent of countries, 

 together with the large additional parts ftill forming on its coaft, 

 appear to be the produdlions of two of the greateft rivers on 

 the globe, the Amazons and the Oroonoko. If you caft your 

 eye upon the map, you will obferve from Cayenne to the 

 bottom of the gulph of Paria, this immenfe tradl of fwamp, 

 formed by the fediment of thefe rivers, and a fimilar tra(5l of 

 fhallow muddy coaft, which their continued operation will 

 one day elevate. The fediment of the Amazons is carried 

 dovv^n thus to leeward (the weftward) by the conftant currents, 

 * which 



