126 CRUISE OF STEAMER CORWIN IN THE ARCTIC OCEAN. 



In a paper read before the Geographical Society of the Pacific, soon after my return from the 

 Arctic Ocean in 1881, I stated my belief in a tidal current in Bering Sea and the Arctic Ocean, 

 and also that a branch of the Kuro Siwo, or Japanese Warm Stream (so called), passes through 

 Bering Strait; both, however, subject to the ever varying condition of wind and ice. Having 

 shown in the preceding pages the grounds upon which I based my opinion, I will now explain the 

 meaning of the term " Japanese Warm Stream " in the sense in which I used it. In this I cannot do 

 better than quote from Thalassa an essay on the depth, temperature, and currents of the ocean by 

 John James Wild, a member of the civilian scientific staff of the Challenger : 



A branch of the North Pacific equatorial current flows into the basin between the Philippine ami Lad roue 

 Islands, which basin, like the Caribbean Sea, is separated from the oceau by a chain of islands, the projecting points 

 of a submarine ridge, and the northern and narrow half of this basin stands in the same relation to the southern 

 half as the Mexican Gulf to the Caribbean Sea. The current, after passing along the east coast of the Philippines, 

 of Formosa, and the islands which connect the latter with Japan, has to force its way, and, like the Gulf Stream, in the 

 face of a polar current over the shallow harrier which joius Japan with the chain of islands terminating with the 

 Ladroue group. After crossing this barrier it unites itself to the portion of the North Pacific equatorial current, 

 which flows along the eastern side of these islands, and the two combined form the Kuro Siwo, whose waters are 

 traced through Bering Strait into the Arctic Basin, and to the eastward so far as the coast of North America. 



The Kuro Siwo, thus defined, may be compared for the purpose of illustration to the Gulf 

 Stream of the Atlantic, and each may be described in a few words as a small portion of the great 

 equatorial current cut off for a time from the main body by intervening islands, and uniting with 

 it again as soon as the obstructions will permit, when it loses its own identity in the greater 

 current. In applying this name to the origin of the current which my observations lead me to 

 believe passes through Bering Strait I referred not to the small stream separated from the main 

 body of the equatorial current by the Japan islands, and which flows northward as a separate 

 stream only so long as it is separated by these islands, but to the western edge of the great 

 equatorial current which makes the circuit of the North Pacific, and to which the name of the 

 smaller stream has been applied. The impossibility of this small stream maintaining a separate 

 existence from the Japan islands to Bering Strait must be apparent when we consider the fact 

 that it emerges from the islands, by which it has been separated from the main current, with a 

 depth of only about 100 fathoms, and average temperature of 84°, and a velocity of about 

 75 miles per day. Beneath this shallow stream of warm water the temperature of the sea rapidly 

 falls to within a few degrees of the freezing point. By the application of the known principle 

 that two strata of different temperatures cannot remain in contact without producing a third 

 stratum of intermediate temperature we see that the high temperature of this comparatively 

 small stream would soon be reduced by contact with the lower temperature of the under current, 

 and its velocity would become less in direct proportion to the distance traveled, gradually 

 accommodating itself in these particulars to the other and larger currents with which it would 

 come in contact. 



Bodies of sea water of the same specific gravity when brought in contact mingle and become 

 as one. The specific gravity of sea water depends upon the temperature and the amount of saline 

 matter held in solution, and these conditions, to a certain extent, depend one upon the other, the 

 higher the temperature the greater the percentage of salt, owing to the greater evaporation. 

 The Kuro Siwo, being a part of the equatorial current, contains the same percentage of salt, but, 

 owing to its accelerated velocity, retains a greater amount of heat. This, however, as already 

 shown, is soon reduced to that of the surrounding water, and as its percentage of salt is the 

 same the reduction of its temperature increases its specific gravity until it corresponds to the 

 surrounding sea and becomes in all respects a part of it. 



The effects of wind upon the surface currents of the ocean are well understood. To them are 

 due the equatorial currents of both oceans, while ocean currents would occur if uninfluenced by 

 winds, in the constant efforts which are made by the sea to maintain its equilibrium, in spite of 

 disturbances due to difference of temperature and the consequent difference in evaporation. 

 These currents would necessarily be slight and nearly in the direction of the meridian on account 

 of the relative positions of the disturbing elements, heat and cold, and not at right angles to the 

 meridian, as is the case with the equatorial currents of both the Atlantic and Pacific Oceans. 



