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Sect, III.] 



HYDROGRAFHY. 



65 



Senegal 5 Iiidns, Ganges, Yaiigtsee or Irawady, &c. &c. 



5 



observations on the stream should be more closely made, 

 and dis colorations and specific iiravitv of the water noted. 



These and such like stupendous rivers extend then* in- 

 fluence to a considerable distance from the coast,* and 

 occasionally perplex and delay the navigator, who finds 

 himself struggling against a difficulty, wholly unconscious 

 of the cause and ignorant of the facility with which he 

 might escape it by changing his route, f River currents 

 of this description vary their direction according to the 

 courses of the stream along the coast, by blending with 



it, and forming a curve, which vanishes only with their 

 influence upon the ocean current ; so that we are not 

 always to look for the outset from the river at a right 

 angle to the coast, nor always in the same locality, but 



according to the prevailing o 



ir^- 



ug stream. 



The limits of the principal currents of the globe have 



been given (see plate B) in order to apprize the navigator 

 of the places in which he should more closely attend to 

 his observations. If, however, from any cause he may 

 have been prevented continuing the series throughout any 



mts, and should desire to define their 

 limits, he should begin at least a day's run from the 

 places, and continue his register until he is certain of 

 having passed the boundaries, attending closely to the 



curi 



The River Plata, at a distance of GOO miles from the mouth of the 

 river, was fouud to maintain a rate of a mile an hour ; and the Amazon, 

 at 300 m^es from the entrance, was found runniiig nearly three miles 

 per hour, its original direction being but little altered, and its water 

 nearly fresh. — Bennett^ Sabine, 



t See the effect of the Equatorial and Guinea current before-men- 

 tioned, at p. 56. 



