REPORT ON THE KDRO-SIWO, ETC. 365 



One of the most remarkable of these off-shoots is this Kuro-Siwo, or Japan stream, which, 

 separated from the parent current by the Bashee islands, and south end of Formosa, in latitude 

 22° north, longitude 122° east, is deflected to the northward along the east cost of Formosa, 

 where its strength and character are as decidedly marked as those of- the G-ulf stream, on the 

 coast of Florida. This northwardly course continues to the parallel of 26° north, when it 

 bears off to the northward and eastward, washing the whole southeast coast of Japan, as far as 

 the Straits of Sangar — (see thermometric diagrams, Plates IV, V, VI, VII, and XI) — and 

 increasing in strength as it advances, until reaching the chain of islands to the southward of 

 the Gulf of Yedo, about the meridian of 140° East, where its maximum velocity, as shown by 

 our observations on one occasion, was 72, 74, and 80 miles, respectively, per day. — (See tracks 

 of vessels on Plates I, IV, V, VI, VII, XII, XV, and XVI.) Its average strength from tne 

 south end of Formosa to the Straits of Sangar is found to be from 35 to 40 miles per twenty-four 

 hours, at all seasons that we traversed it. 



Near its origin the Kuro-Siwo, like the Gulf stream, is contracted and is usually confined 

 between Formosa and the Majico Sima Islands, with a width of one hundred miles. But to the 

 northward of this group it rapidly expands on its southern limits and reaches the Lew Chew and 

 Bonin Islands, giving it a width to the northward of the latter of about five hundred miles. — 

 (See thermometric diagrams and tracks of vessels on Plates I, II, V, IX, XII, XV, and XVI.) 



To the eastward of the meridian of 143° east, in latitude 40° north, the stream takes a more 

 easterly direction, allowing a cold current to intervene between it and the southern coast of 

 Yesso, where the thermal change in the water on leaving the stream is from 16° to 20°. — (See 

 thermometric diagrams, Plate XI.) But from the harassing prevalence of fogs during the 

 limited stay of the squadron in that vicinity, the reports and tables do not furnish sufficient 

 data to prove conclusively the predominant direction of the cold current through the Straits of 

 Sangar, particularly as the tide ebbs and flows through them with great rapidity. Yet from 

 what we have, I am inclined to believe that it is a current from the Arctic ocean, running 

 counter to the Kuro-Siwo, and which passes to the westward through the Straits of Sangar, 

 down through the Japan Sea, between Corea and the Japanese Islands, and forms the hyper- 

 borean current on the east coast of China, which is known to flow to the southward, through 

 the Formasa channel into the China sea. For to the westward of a line, connecting the 

 north end of Formosa and the southwestern extremity of Japan, there is no flow of tropical 

 waters to the northward, but, on the contrary, a cold countei current filling the space between 

 the Kuro-Siwo and the coast of China. — (See thermometric diagrams, Plates III, VI, VII, and 

 XV.) As far as this cold water extends off the coast, the soundings are regular, and increase 

 gradually in depth ; but simultaneous with the increase of temperature in the water the 

 plummet falls into a trough similar to the bed of the Gulf stream, as ascertained by the United 

 States Coast Survey . 



The surface of this counter current is, no doubt, influenced in some measure by the southwest 

 monsoon, and during the season of that wind a portion of it is forced out between Formosa and 

 Japan, to mingle its waters with the Kuro-Siwo. But so well is its existence known to vessels 

 trading on the coast of China, that they very rarely, if eyer, attempt to beat to the northward 

 through the Formosa channel, but almost invariably make the passage to the eastward of For- 

 mosa during the prevalence of adverse winds, though those winds may be stronger there than 

 in the Formosa channel. 



Of the power of these two currents I can speak from personal experience, in addition to the 



