749 



ference of six months, which results from the 

 situation of the rivers in opposite hemispheres. 

 The commencement of the risings only is less 

 tardy in the Oroonoko. This river increases 

 sensibly as soon as the Sun has crossed the 

 equator ; in the Amazon, on the contrary, the 

 risings do not commence till two months after 

 the equinox. It is known, that in the forests 

 north of the line the rains are earlier, than in 

 the less woody plains of the southern torrid zone. 

 To this local cause is joined another, which acts 

 perhaps equally on the tardy swellings of the 

 Nile. The river Amazon receives a great part 

 of it's waters from the Cordillera of the Andes, 

 where the seasons, as every where among moun- 

 tains, follow a peculiar type, most frequently 

 opposite to that of the low regions. 



The law of the increase and decrease of the 

 Oroonoko is more difficult to determine with 



Nile. The following are the analogous results for two great 

 rivers of South America compared with the Nile. 



OROONOKO. AMAZON. NILE. 



(Lat. 3° to 8° N.) 



Beginning of 



the rise ... April. 

 Maximum ... Aug. 

 Minimum Jan . Fe b . 



(Lat. 3°N.to 16°S.) 



(Lat. 11° 30' to 



31° 15' N.) 

 April (Abyssinia) ; 

 June (Cairo). 

 September. 

 April. 



December. 

 March. 

 July, August. 



The Oroonoko, like the Nile, increases during 100 or 115 

 days. The maximum of the Rio del Norte is in May. (Pol. 

 Essay, vol. i, p. 303.) 



