428 ■ EXPEDITION TO JAPAN. 



Tliis commences on the south end of the ishxnd of Formosa, and is undoubtedly part of the 

 great equatorial current of the Pacific. The larger portion of this current, when it reaches the 

 point just named, passes off into the China sea ; while the other part is deflected to the 

 northward, passing along the eastern coast of Formosa, where its strength and character are 

 unequivocally shown, and extending itself, at times, as far to the eastward as the Lew Chew 

 islands, where the increased temperature of the water shows the presence of a torrid current. 

 Its northwardly course, however, continues as far as the parallel of 26°, when it hears off to the 

 northward and eastward, washing the whole southeastern coast of Japan as far as the Straits of 

 Sangar, and increasing in strength as it advances. At the chain of islands south of the Gulf of 

 Yedo, about the meridian of 140° E., its maximixm strength on one occasion was observed to be 

 seventy-two, seventy-four, and eighty miles per diem, respectively, on three successive days. 

 From the south end of Formosa to the Straits of Sangar, its average velocity was found to be 

 from thirty-five to forty miles per day, at all seasons when our ships traversed it. Its precise 

 width south of the Gulf of Yedo was not satisfactorily ascertained, but enough was discovered 

 to make it certain that it reaches to the southward of Fatsicio, and it extends perhaps even to 

 the Boniu Islands in latitude 26° N. 



In the latitude of 40° N. and to the eastward of the meridian 143° E. the stream turns more 

 to the eastward, and thus allows a cold counter-current to intervene between it and the southern 

 coast of the island of Yesso. Our hydrographers could not positively ascertain the fact, but 

 they believed that this hyperborean current, found on the coast of Yesso, passes to the westward 

 through the Straits of Sangar down through the Japan sea, between Corea and the Japanese 

 islands, finding an outlet through the Formosa channel into the China sea. The data they 

 had^ together with the known fact that a strong southwardly current prevails between Formosa 

 and the coast of China, particularly during the northeast monsoon, when the northwardly 

 current along the cast coast of Formosa continues unimpeded, would seem to give jirobability to 

 this conjecture of the gentlemen. The southwest monsoon may possibly affect this counter- 

 current, and force it to mingle its waters with those of the Kuro-siwo, or "Japanese gulf 

 stream," between the north end of Formosa and the southwest extremity of Japan. The 

 Vandalia was ordered from Hakodadi, to pass westward through the Straits of Sangar and 

 proceed to China, on the western side of Japan. One object of this was to make observations on 

 current and temperature ; but, unfortunately, the Commodore left China before the report was 

 made, and it has -never reached him. 



The existence of this counter-current, however^ is so well known by vessels trading on the 

 coast of China, that they seldom attempt to heat to the northward through the Formosa channel, 

 but usually make the passage to the eastward of Formosa during adverse winds, even though 

 such winds may be stronger on the east side of the island than in the Formosa channel. 

 Lieutenant Bent traced also some striking analogies between this Kuro-siwo (great stream) of 

 Japan, and our gulf stream. His observations were strikingly confirmatory of the views that 

 have been expressed both by Mr, Kedfield and Lieutenant M. F. Maury, as to the cause of the 

 deflection of the Atlantic gulf stream to the eastward, and the cold counter-current below or 

 between it and the shore. The first is not caused by the water impinging on land, and being 

 thereby turned to the east, but by the greater rotative velocity of the latitudes at and near the 

 equator, which throw the gulf stream eastward ; and the second is produced by the tardy 

 rotation of the high latitudes operating on the cold counter-current setting southward from the 



