348 ' 0« the Natural Hijory of Guiana. 



defcribed. Some of thefe are alfo very extenfive. Few herbaceous vegetables are to be 

 met with upon them. Broad fpaces of arid fand are interfered by clumps of flirubbery. 

 Nothing grows to the height of a tree ; but a particular fet of plants, different from thofe 

 in other parts of the country, find fubfiftence enough to rife to fifteen or thirty feet. How 

 Nature, after all her efforts, fhould have failed to induce a foil upon thefe is furprifing. It 

 appears chiefly owing to the great porofity of the fand, which every where admits the de- 

 cayed vegetable matter deftined for that purpofe to be carried down through it, and filtered 

 ofFby the rain. Even thofe fand-hills which are covered by tall trees, (till fhew proofs of 

 this. The trifling layer of mould formed upon them is exceedingly thin. When cleared, 

 they are very barren ; and when you dig in them to a great depth, you flill find fmall por- 

 tions of black vegetable earth difperfed among the fand. What corroborates the above 

 liippofition is the appearance of the fprings. Abundance of thefe are found gufhing out 

 copioufly round the verges of the hills ; and notwithftanding the extreme whitenefs and 

 purity of the fand from whence they flow, there is not one in an hundred whofe waters 

 are limpid. They come -out not muddy, but of a brownifh colour, very much like the 

 water which runs from peat-molTes, and they are certainly tinged by the fame caufe. The 

 rotten leaves of trees, and other decayed parts of vegetables on the hills, inftead of being 

 colledled on the furface to form foil, are wafhed down into the fand (trata by every rain ; 

 fo that the refervoirs of the fprings, and the water which proceeds from them, are always 

 coloured with thefe fubftances. There follows a corollary alfo from this general principle, 

 and, when compared with fads, 1 believe it will hold good : The more the fand is con- 

 creted into ftone in any of the hills, the more and better will be the foil upon them. Where 

 clay in fmall beds, or in a certain proportion, is mixed with the fand, the vegetable mould 

 will likewife be better retained. , 



Rivers. — I will next give you what general obfervations I have been able to make upon 

 the rivers and creeks of this part of America. The courfe of nearly qll thofe of Guiana is 

 from fouth to north. They originate in a chain of hills running eaft and wefl, which fepa- 

 rates Guiana from the country of the Amazons, and likewife gives rife, on its fouth fide, to 

 the numerous branches which fall into that river. The Demerary is a confiderable ftream, 

 equal if not fuperior to the Thames ; yet it is by no means among the largeft of them. 

 The ElTequebo is five times larger at its mouth, forming a whole Archipelago of iflands ; 

 but its ftream foon divides, and, on account of rocks, fliallows, and rapids, none of its 

 branches are navigable fo high up as the former. Moft of the particulars I am now to give 

 you, muft be underflood as applying to the Demerary. The bar, if it may be fo called, is 

 common to this with many other rivers which difcharge themfelves into a fhallow fea ; but 

 ftill with circumftances in the prefent cafe which diftinguifh it from others where the bot- 

 tom is not mud but fand. It does not run like a fingle narrow ridge, acrofs or nearly 

 acrofs the mouth of the river ; but it is of great extent, and is properly a continuation of the 

 mud-bank which runs all along the coaft. To the eaft and weft, and for two miles or more 

 in the ofEng, you have ten or twelve feet water, with the utmoft uniformity ; and ftanding 

 in with the mouth of the river open, you neither deepen nor (hallow till you enter it, when 

 you fir^two, three, four, and five fathom; and it continues to average that depth for a 

 long way, fo that any veflel which can enter, may, for draught of water, proceed up the 

 jriver for 100 miles or more. 



The 



