OUBRENT OF THE OEIXOCO. 15 



rise in the Lower Orinoco. M. Depons, who has in general 

 collected very accurate notions during his stay at Caracas, 

 fixes it at thirteen fathoms. The heights naturally vary 

 according to the breadth of the bed and the number of 

 tributary streams which the principal trunk receives. 



The people believe that every five years the Orinoco rises 

 three feet higher than common ; but the idea of this cycle 

 does not rest on any precise measures. We know by the 

 testimony of antiquity, that the oscillations of the Nile have 

 been sensibly the same with respect to their height and 

 duration for* thousands of years; which is a proof, well 

 worthy of attention, that the mean state of the humidity 

 and the temperature does not vary in that vast basin. Will 

 this constancy in physical phenomena, this equilibrium of 

 the elements, be preserved in the New World also after 

 some ages of cultivation ? I think we may reply in the 

 affirmative ; for the united efforts of man cannot fail to have 

 an influence on the general causes on which the climate of 

 Guiana depends. 



According to the barometric height of San Fernando de 

 Apure, I find from that town to the Boca de Navios the slope 

 of the Apure and the Lower Orinoco to be three inches and 

 a quarter to a nautical mile of nine hundred and fifty toises.* 

 We may be surprised at the strength of the current in a 

 elope so little perceptible ; but I shall remind the reader on 

 this occasion, that, according to measurements made ':>y order 

 of Mr. Hastings, the Ganges was found, in a course of sixty 

 miles (comprising the windings,) to have also only four inches 

 fall to a mile ; that the mean swiftness of this river is, in 

 the seasons of drought, three miles an hour, and in those of 

 rains six or eight miles. The strength of the current, there- 

 lore, in the Ganges as in the Orinoco, depends less on the 

 slope of the bed, than on the accumulation of the higher 

 waters, caused by the abundance of the rains, and the num- 

 ber of tributary streams. European colonists have already 



the Orinoco, p. 38. Gumilla, vol. i, p. 5659. Depons, vol. iii, p. 301. 

 The greatest height of the rise of the Mississippi is, at Natchez, fifty-five 

 English feet. This river (the largest perhaps of the whole temperate 

 tone) is at its maximum from February to May; at its minimum in 

 August and September. Ellicott, Journal of an Expedition to the Ohio, 

 t The Apure itself has a slope of thirteen inches to the mile. 



