of a direct Passaged over the Pole. 303 



their limits. Suffice it to say, what more particularly applies to 

 the North Pacific, and will lead us again to the Arctic regions. 



Having said that the air is rarefied and raised in tl)e atmo- 

 sphere, and that the greatest degree of evaporation is effected 

 between the west coas,t of Africa and the east coast of America; 

 and that north of the line, the fluid is so returned louards the 

 North Pole, and being condensed somewhere in its passage by 

 cold, it perhaps supplies with water some of the rivers which dis- 

 charge into the seas of the temperate zone, or into the polar 

 ocean ; and whether, falling in ram, hail, or snov/ upon the earth 

 or not, it ultimately finds its way into the ocean ; and according 

 to the temperature proportionate to its depth, the water takes a 

 direction towards the regions of equatorial heat, is again raised 

 by that heat to the surface, and again evaporated. For experi- 

 ments in the ocean have proved, that when the temperature of 

 the aimospliere exceeds that of the surface of the sea, the super- 

 ficial water is generally warmer than that at certain depths le- 

 neatk it, (I say generally, because in soundings, and confined 

 waters, local causes effect many exceptions to this general rule), 

 and in all probabilitv, the greater the depth the colder the fluid in 

 that case. And as we know, that when the air (or water) re- 

 ceives an increase of heat, its parts will be put in motion towards 

 that heat, it follows that the colder water throughout its whole 

 depth, must have a tendency to flow towards the point of greatest 

 heat ; and be continually rising towards the surface in the equa- 

 torial regions. This probably is the routine of the general move- 

 ment of the atmosphere, and the waters of the ocean, between 

 Europe, Africa, and America, from the Arctic regions to the 

 equator; and it seems no less probable, that in the Pacific, they 

 are subject to the same general laws. For there also the greai 

 equatorial current is in constant motion to the westward, and 

 like the eulf stream, and from causes too in so7ne points similar, 

 it gradually turns to the northward, when it approaches the lands 

 to the northward of New Guinea, and the Philippine Islands; 

 and being perhaps at the same time influenced by currents setting 

 in a different direction, more particularly during the prevalence 

 of the S.W. monsoon in the India and China seas. 



Near the coast of Japan, the current has been found to set 

 N.E. by N. at the rateof five knots an hour. At eighteen leagues 

 distance, about three knots in the same direction, but at a greater 

 distance from the land, it inclined more to the eastward ; and at 

 sixty leagues from the land, it set E.N.E. three miles an hour; 

 then (like the gulf stream), inclining gradually to the southward; 

 80 that at the distance of 120 leagues from the coast of Nipon, its 

 direction was S.E. and its rate not more than a knot an hour. From 

 this current setting generally to the N.E. along thecoast of Japan 



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