274 The Ajstdes aito the Amazon. 



Though not so rapid as the Mississippi, the Amazon is 

 deeper. There are seven fathoms of water at Nauta (2200 

 miles from the Atlantic), eleven at Tabatinga, and twenty- 

 seven on the average below Manaos.* 



The Amazon and its branches are subject to an annual 

 rise of great regularity. It does not take place simultane- 

 ously over the whole river, but there is a succession of 

 freshets. At the foot of the Andes the rise commences in 

 January; at Ega it begins about the end of February. 

 Coinciding with this contribution from the west, the Octo- 

 ber rains on the highlands of Bolivia and Brazil swell the 

 southern tributaries, whose accumulated floods reach the 

 main stream in February; and the latter, unable to dis- 

 charge the avalanche of waters, inundates a vast area, and 

 even crowds up the northern tributaries. As the Madeira, 

 Tapajos, and Pufus subside, the Negro, fed by the spring 

 rains in Guiana and Venezuela, presses downward till the 

 central stream rolls back the now sluggish affluents from 

 the south. There is, therefore, a rhythmical correspond- 

 ence in the rise and fall of the arms of the Amazon, so 

 that this great fresh-water sea sways alternately north and 

 south ; while the onward swell in the grand trunk is a pro- 

 gressive undulation eastward. As the Cambridge Professor 

 well says : " In this oceanic river the tidal action has an an- 

 nual instead of a daily ebb and flow ; it obeys a larger orb, 

 and is ruled by the sun and not the moon." As the south- 

 ern affluents have the greatest volume, the Amazon receives 

 its largest accession after the sun has been in the southern 

 hemisphere. The rise is gradual, increasing to one foot 

 per day. One lowland after another sinks beneath the 

 flood ; the forest stands up to its middle in the water, and 



* The assertion of the Ency. Metropolitana, that "its cun-ent has great vio- 

 lence and rapidity, and its depth is unfathomable," must be received with 

 some allowance. 



