REPORT MADE TO COMMODORE M. C. PERRY 



KURO-SIWO, OR GULF STREAM OP THE NORTH PACIFIC OCEAN; 



BY LIEUT. SILAS BENT. 



Japan Expedition Office, 



New York, January 10, 1857. 



Sir : In obedience to your orders, I have made a careful examination of the monthly meteoro- 

 logical tables and reports of the masters of the several vessels of the late Expedition to Japan, 

 and extracted from them such data and information as I deemed of interest to science, or of 

 importance to navigation, and have succeeded in tabulating and arranging the first in such form 

 as will, I trust, prove satisfactory in elucidating the process by which the general results were 

 obtained. 



Scattered over the ocean and seas, extending from the south coast of China to the northeast 

 extremity of Japan, during a period of eighteen months of stirring activity, the squadron 

 traversed that whole region, in every direction ; and these reports, written with intelligence, 

 and their accompanying tables, compiled with care, furnish a full and valuable collection of 

 consecutive observations, which show conclusively that there is a " river in the ocean," flowing 

 to the northward and eastward along the coast of Asia, corresponding, in every essential point, 

 with the Gulf stream of the Atlantic. 



All the observations contained in these tables I at first plotted on a skeleton chart, but found 

 that no satisfactory conclusion could be adduced from them in such a form, owing to the con- 

 fusion produced by the unavoidable discrepancies arising from careless steerage, or local devia- 

 tion of the compasses, irregular atmospheric pressure, and influences of shifting winds and 

 neighboring land ; and that, so far as the defining of the limits and general direction of great 

 oceanic currents were concerned, the thermometers were the only sure and safe guides. I there- 

 fore made the accompanying series of diagrams of the various passages of the ships between the 

 coasts of China and Japan, the Lew Chew, Bonin, and Sandwich Islands, in order to exhibit the 

 tracks, daily winds, currents, mean diurnal atmospheric pressure, and temperatures of the air 

 and water, and to convey to the mind, by a simple inspection, if possible, the most satisfactory 

 information and results in regard to the important stream in that region of the Pacific ocean. 



These diagrams are confined mostly to the sailing vessels, as the wheel-currents of the steamers, 

 when the patent log is not used, invariably embarrasses the reckoning, unless in the most 

 favorable weather. 



By a reference to the diagrams, it will be perceived that the first horizontal column at the top 

 of the plate, marked "daily winds," gives the average direction of the wind by initial letters, 

 corresponding to the vertical lines extending do\wiward from that column, which lines repre- 



