35 a On the Natural Hijory of Guiana. 



the infancy of fcicncc, is now a well-known phenomenon to every inhabitant of a conti. 

 nent in the torrid zone. From the fituation of the river Amazons, it amounts to a cer- 

 tainty, that the Demerary, Eflequebo, and other rivers of Guiana, cannot originate very 

 far up in the continent of South America. This is confirmed by what I could learn of 

 the rife and duration of the floods of thefe two rivers. Enquiring about them at the 

 plantations below is to little purpofe, for there the floods are hardly difcernible j but by 

 the poll-holder, and the fettlcrs farthcft up, I was informed that they are there feiifible 

 enough, and that, independent of all partial fwells from accidental rains, the Demeriiry 

 generally rofe every year in the month of June, and continued high through July and 

 part of Auguft. The rife there upon the whole might be about twelve feet ; it is fufii- 

 cient to lay the level parts of the country under water, and to render the woods that 

 cover them in feveral places pafluble in canoes. We could have willied for more esa£l 

 information. This, however, was fufilcient to prove that the rivers did not rife very far 

 inland, elfe the floods would have been later in the year ; but at the fame time that they 

 were of extent enough to follow the rule of all confiderable intertropical rivers, fo as to- 

 have a flood in the rainy feafon, that is, in the months when the fun is upon the fame fide 

 of the line on which they have their origin and courfe. 



The great Oronooko, I have been informed, begins to rife a little in May : it conti- 

 nues increafing through the fummer months, and the inundation is at its height in Sep- 

 tember. At that time, as far up as the Angufturas, the rife is above forty feet perpendi- 

 cular above the low water mark. It diminiflies as you defcend, till about the mouth, where 

 it is only a very few feet. 



Tides are of the utmoft confequence to the inhabitants of the coaft of Gniana. They 

 enable them to drain a country which otherwife would never have been cleared, and they 

 afcertain their journeys, which are made by water up and down the rivers, and even along 

 the coall. At the mouth of the Demerary it is high water at about half part 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, fcldom lefs thai* 

 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 becomes feebler; and for a confiderable difl;ance 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 con- 

 ftantly down, only more gentle during the rife or flood ; and there alfo the continuance 

 of the rife is very fhort, not more than two or three hours. 



Some obfervations upon the foil of the different parts of the country may be the fub- 

 je£l of a future communication. I will only add, at prefent, what I think has more than 

 conjectural foundation ; viz. that this moft recent of countries, together with the large 

 additional parts ftill forming on its coait, appear to be the prod unions of two of the 

 greateft rivers on the globe, the Amazons and the Oronooko. If you caft your eye upon 

 the map, you will obferve, from Cayenne to the bottom of the Gulph of Paria, this im- 

 menfe tra£t of fwamp, formed by the fediment of thefe rivers, and a fimilar tra£l of 

 fhallow muddy coaft:, which their continued operation will one day elevate. The fedi- 

 inent of the Amazons is carried down thus to leeward (the weflwardj, by the conftant, 

 Oirrents which fet along from the fouthward and the coafl of Brazil, That of the Oro- 

 nooko 



