24 AUSTKALASIA. 



circumference of the planet. Compared witli such an oceanic current all the 

 rivers flowing from the continental regions seawards sink into insignificance. 

 The discharge is at least 70,000 millions of cubic feet per second. 



This vast central current, main branch of the system of secondary streams 

 developed in the rest of the ocean, gives rise to two great lateral backwaters, one 

 in the North Pacific, the other in the Southern Ocean. Taking the same course 

 as the monsoons of the Caroline Archipelago, the waters of the equatorial stream 

 are deflected towards the north-west in the direction of Japan ; then on approaching 

 the Chinese seaboard they follow the coast towards the north-east, and under the 

 name of Kuro-Sivo, or " Black Stream," expand into a vast curve across the North 

 Pacific. Although gradually losing the character of a current in the strict sense 

 of the term, it sets slowly along the coasts of British North America, the United 

 States, and Lower California, ultimately rejoining the equatorial current. 



To this great stream in the northern corresponds another in the southern 

 hemisphere. South of the equatorial seas a liquid mass jDassing east and Avest of 

 New Zealand turns south to the austral waters, and by a curve sj'mmetrical with 

 that of the Kuro-Sivo merges west of Chili in a littoral current, which skirts the 

 American coast till it becomes again absorbed in the equatorial stream. An 

 analogous movement takes place in the Indian Ocean, where the waters of the hot 

 zone also set slowly in the direction of the west. At Madagascar they ramif}^ into 

 two branches, which flow southwards, and in the Antarctic regions form a junction 

 with a return current, which aftei" coasting the West Australian seaboard rejoin 

 the equatorial waters. 



But although analogous in their muin features these three great movements 

 present many striking differences in their details, according as they are affected 

 by the course of the winds, the depths of the seas, the form and disposition of 

 the neighbouring lands. In many places the more sluggish waters quicken their 

 speed, and in the very heart of the sea is thus developed a sort of river, whose 

 water is distinguished from that on either side both by its colour and velocity. 

 The friction against its liquid banks causes it to oscillate in short waves like those 

 of a fluvial rapid, while the conflict of waters of varying temperature gives rise to 

 fogs spreading over vast spaces. Such phenomena are observed chiefly about the 

 Kuro-Sivo of Japan and its eastern extension across the North Pacific. 



Each counter current has also its lateral streams, which penetrate into the 

 straits and inlets, as well as its tributaries of cold water flowing from the polar seas. 

 An incessant interchange goes on between the tepid floods of the equatorial regions 

 and those of low temperature coming from the frigid zone. These polar waters 

 move bodily in the direction rf the equator, in order to replace the losses caused by 

 evaporation under the tropical latitudes. According to the course of the winds, 

 the form of the marine bed and of the seaboards, this collective displacement 

 becomes decomposed in second ary and more rapid streams, some of which flow by 

 the side of those setting in the contrary direction from the equator, while others 

 passing underneath them continue their course at lower depths. 



At first sight it might be supposed that all the polar streams, being colder and 



