relative to the Earth's Surface. 49 
along the coast from the north, and on the west coast of South 
America is Humboldt’s current, much colder than the rest of the 
ocean in the same latitude, both tending toward the equator to 
join the great westward current there across the Pacific, and to 
fill up, as it were, the vacuum which this current has a tendency 
to leave about the equator, on the west coast of America. 
47. With regard to the gyratory motion of the oceans, it may 
be further added here, that such gyrations are clearly demon- 
strated by the positions of the isothermal lines, as has been 
shown by Professor Dana, in a paper read at the twelfth meeting 
of the American Association for the Advancement of Science 
(Proceedings, vol. xii, p . According to this paper, the 
isothermal line of 68° F., in winter, extends, in the North At- 
lantic, from 56° N. on the American side, to 12° N. on the 
frican, and in the South Atlantic, from latitude 31° S. on the 
South American coast, to 7° S. on the African side. Similar 
evidences are given of gyratory motions, in a less degree, in both 
the North and South Pacific, and also in the Indian Ocean 
” en a portion of fluid on the earth’s surface gyrates from, 
left to right, the deflecting force arising from the earth’s rotation 
being in this case toward the interior, the surface assumes a 
slightly convex form. The water of the North Atlantic having 
a very small gyratory velocity in comparison with that o 
earth’s rotation, the interior is a little elevated above the general 
‘level, and consequently the pressure upon the bottom increased. 
ow the gyrations which cause this elevation in the middle being 
principally toward the top, the increased pressure upon the bot- | 
tom causes the fluid there to flow out on all sides with a very 
small velocity, towards the circumference, and hence the water 
at the surface has a slight tendency to flow in from all sides to- . 
wards the interior to supply its place. This completely accounts 
for that vast accumulation of drift and sea-weed, covering a large 
portion of the interior of the North Atlantic, called the Sargasso 
rom what has been stated, the North Pacific must als 
have a slight gyratory motion from left to right, and hence it 
likewise has its Sargasso Sea. ! 
V. The Motions of Solid Bodies at the Earth’s Surface. 
49. Tt has been shown that if a body were set in motion upo 
_ the earth’s surface it would move with uniform velocity, 
_» Would be continually deflected to one side. When the range of — 
_ Motion is s cos 9 (equations (5)) may be regarded as con- 
Stant, and hence the deflecting force in this case is’¢o: and 
pre cause the body set in motion to describe the ¢ 
ie . 
le. If we pute for the radius of curvature, nd m for 
: 
d 
_ Am. Jour. Sci—Snconp Sertms, Vou. XXX, No. 91.—Jan., 1861. 
q 
