88 THE TROPICAL WORLD. 



waters wliich, during the rainy season, rushes in one second 

 through the strait, is estimated by Von Martins at 500,000 cubic 

 feet, — enough to fill all the streams of Europe with an exuberant 

 current. 



The tides extend as far as Obydos, though still 400 miles 

 from the sea ; and according to La Condamine, they are even 

 perceptible as far as the confluence of the Madeira. But so 

 slow is their progress upwards, that seven floods, with their 

 intervening ebbs, roll simultaneously along upon the giant 

 stream ; and thus, four days after the tide-wave was first raised 

 in the wide deserts of the South Sea, its last undulations expire 

 in the solitudes of Brazil.^ 



The next considerable vassal of the Amazons is the shallow 

 Tapajos. 



Fancy six streams, like the Thames, strung successively 

 together, and you have the length of this river ; take the Ehine 

 twice from its source in the glacier of Mount Adula to the sands 

 of Katwyck, and you have the measure of the Xingu. Before the 

 confluence of this last of its great tributaries, — for the Tocan- 

 tines, though considered by some geographers as a vassal, is in 

 reality an independent stream, — the breadth of the Amazons 

 appeared to Von Martins equal to that of the Lake of Constance ; 

 but soon even this enormous bed becomes too narrow for the vast 

 volume of its waters, for below Grurupa it widens to an enormous 

 gulf, which might justly be called the 'Bay of the Thousand 

 Isles.' Nobody has ever counted their numbers ; no map gives 

 us an idea of this labyrinth. If we reckon the island of Marajo, 

 which equals Sicily in size, to the delta of the Amazons, its 

 extreme width on reaching the ocean is not inferior to that of 

 the Baltic in its greatest breadth. 



Dangerous sand-banks guard the giant's threshold ; and no 

 less perilous to the navigator is the famous Pororocca, or the 

 rapid rising of the spring-tide at the shallow mouths of the chief 

 stream and of some of its embranchments, — a phenomenon 

 which, though taking place at the mouth of many other rivers, 

 such as the Hooghly, the Indus, the Dordogne, and the Seine, f 

 nowhere assumes such dimensions as here, where the colossal 

 wave frequently rises suddenly along the whole width of the 



* ' The Sea and its Living Wonders.' Second Edition, p. 41. 

 t Ibid, p. 40. 



