REPORT ON THE KURO-SIWO, ETC. 367 



sub-surface currents, none of which were made by the expedition, as its special object was of 

 primary importance, and all other subjects within the field of our observations were necessarily 

 of subordinate consideration, and were obliged to be made as opportunity and the ordinary 

 facilities of our situation would permit. 



Lieutenant M. F. Maury says that "the maximum temperature of the Gulf stream is 86°, 

 or about 9° above the ocean temperature due to the latitude." This maximum temperature 

 coincides pretty nearly with that of the Kuro-Siwo, as shown by the daily means of our obser- 

 vations ; but the difference between the temperature of the Kuro-Siwo and the "ocean tempera- 

 ture due to the latitude" is, by the same observations, shown to be greater than that of the 

 Gulf stream, amounting on an average to about 12°. — (See Thermometric Diagrams, Plates II, 

 VI, VII, XI, XIII, XV, and XVI. 



There is a floating sea-weed found in the Kuro-Siwo similar in appearance to the fucus natans 

 of the Gulf stream ; but the specimens collected by the expedition were unfortunately lost before 

 being submitted to botanists for examination, and it is therefore yet undetermined whether they 

 are identical or not. 



It may not be uninteresting to state that Lieutenant Wm. L. Maury found sprigs of coral 

 while surveying off the harbor of Simoda, in latitude 35° north. 



I would further call your attention to the chart upon which they are traced, to show the 

 striking coincidence in the recurvation not only of these oceanic streams, but also to the general 

 coincidence in their recurvation with that of the storms of the northern hemisphere. Mr. Ked- 

 field is of the opinion that the recurvation of storms between the parallels of 20° and 30° north 

 and south latitude, in all parts of the world, as shown by observations, is but partially 

 dependent upon the influence of land, and is "to be ascribed mainly to the mechanical gravita- 

 tion of the atmospheric strata as connected with the rotative and orbital movements of the 

 different parts of the earth's surface. — (Naval Mag., 1836, p. 318.) 



These atmospheric meteors, originating generally about the tenth parallels of latitude, north 

 and south, are impelled by this influence directly towards the poles, but are at the same time 

 borne to the westward by the trade winds. This compound force gives them an oblique direc- 

 tion to the northwest and southwest, until arriving at the outer limits of these winds, about the 

 parallels of 25° or 30°, where the storms become released from their influence, and, continuing 

 their course to the north and south towards portions of the earth's surface having less rotative 

 velocity than that from whence they came, they gradually recurve, and soon assume a path to 

 the northeast and southeast, which they pursue until dissipated by expansion, or have fulfilled 

 their mission by a restoration of the atmospheric equilibrium, a disturbance of which had 

 probably given rise to them. The converse of this rotary influence of the earth is thus described 

 by Dr. Hadley and Dr. Franklin : " The air under the equator and between the tropics, being 

 constantly heated and rarified by the sun, rises ; its place is supplied by air from the higher 

 and polar latitudes, which, coming from parts of the earth that had less motion and not sud- 

 denly acquiring the quicker motion of the equatorial earth, becomes an east wind blowing 

 westward, the earth moving from west to east and slipping under the air." This general law 

 of nature operates in the same manner upon the waters of the ocean as upon the atmosphere, 

 when, by any disturbing cause, portions of the former are set in motion from about the equator, 

 modified, of course, by such local obstructions of continents, islands, &c, as may be encoun- 

 tered in their path. 



In the American Coast Pilot, edition of 1837, pp. 666, 667, Mr. Redfield furthermore says : 



