Year: 1874

Physical Geography OF the Sea.
| Two important expeditions, now engaged In
| oceanic research, one in the Atlantic and one
in the Pacific, have recently reported some OF
the results of their kabors, which will proba-
bly, put new phase on the great problem they
! are seeking to elucidate.


We have very lately published the full ac-
count of Commander Belknap's extensive sur
vey Of the bottom of the Pacific lying north of
the great Equatorial current. While his aim
has been specifically to test the telegraphc
accommodations of the North Pacific bed, his
soundings reveal On important principle never
fully, if at all, known to physical geographers-
When about a hundred miles southeast OF
Sendai Bay, on the east coast of Japan and
directly in the strong sweep of the Kuro Siwo
or Japan current the sounding indicated
abyssal depths, while little further north
ward, on the great circle route from Yokohama
to Puget's Sound, the snker carried the wire
to the astounding depth of 4,643 faith
oms without reaching bottom. "The
tooth of running water is very sharp
is an axiom of physical geography,
which, in the curve of the great Pacific Gulf
Stream, might we'll have occurred to the
explorer. And he rightly concludes that his
experiment confirmed the existence of very
| deep trough under the Japan stream similar
to that cut by the Gulf Stream on our own
coast" The discovery that these enormous
''rivers in the ocean, carve their channels
through the solid basin of the great oceans is
very suggestive to the physicist 1t is known
| that they do not extend to the bottom, the
| deep sea thermometer ever assuring US that
the warm strata cease long before the floor Of
the ocean is reached. It would seem, there
fore, to follow, from the facts brought to
light, that these two hot gulf streams act
upon the underlying cushions of cold water
and by mechanical impact cause the abrasion
or erosion of the bottom over which they run.
| 1t is by no means inconceivable that the rest
less on-howing surface currents, by imparting
their own motion to the subjacent water,
make their impression on the oceanic floor
| itself. much as the constant running of the
railway train imbeds the rails in the sleepers
| of the track and the seepers in the road bed.
This, at least seems to be the meaning of the
striking phenomenon discovered by the ex-
plorers in the Western Pacific


The latest reports from Captain Davis, Of
the Challenger expedition, present yet more
astonishing and most instructive discovery,
likely to revolutionize the whole theory of
marine circulation, and putting an efectual
quietus on the interminable theorizings of DR..
Carpenter and his verbose school, The Chal-
lenger's thermometric surveys Of the Atlantic
are so numerous and exact that they afford
data for constructing a better map of the
Atlantic sea bed than we had Of North Amer-
can geography at the beginning of this CEN
| tury The contours of the North Atlantic
present an irregular belt, shaped like the
letter % reversed exceeding twenty-five hun
dred fathoms in depth, from very near the
| coast of the United States and the Bahamas
| toward the African coast between the Canaries
and Cape Verde Islands. North of this lies
submarine bank, rising to within less than
two thousand tathoms of the surface, and
stretching from Greenland to the Azores. 1t
has always been supposed that over this sec
ton poured cold stream of Arctic water on
its way southwark, slowly warming as it
neared the Equator. But the Challenger S
soundings prove the startling fact that
(beneath the water Immediately affected by
the suns rays, believed not to extend more
than eighty fathoms) all the water in the North
Atlantic as far north as the fortieth degree of
latitude, is actually warmer than at the same
depths under the Equator itself! Such dis
covery was never suspected, and only the
unerrng and inexorable register of the
deep-sea thermometer could have suggested
such an apparent anomaly. What is the
solution2


There being bottom water of o temperature
of thirty-two degrees four minutes at the
Equator, with warmer water at all stations to
the north of it. Captain Davis, of the Chal-
lenger, argues, with great sagacity, that it
proves unmistakably that the bottom cold
water of the North Atlantic comes from the
Antarctic region and not from the Arctic
Certainly, if at the Equator the bottom water
supplied from the southwark retains its cold
80 tenaciously. the bottom water Of the North
Atlantic, if supplied from the nearer Arctic
region, should be at least as cold But the
bottom temperature increases decidedly as we
go north of the Line, showing that the vast
submarine drift from the Antarctic flows over
the Atlantic floor across the Equator and
penetrates our hemisphere at least as far as
forty degrees north. This fact apparently up
sets nearly all the prevailing theories, if not
every theory that has ever been current, and
demonstrates that the circulation of the sea is
not carried on between the Polar and Equa-
torial basins, but between the Antarctic Ocean
and the North Atlantic on the one hand, and
probably between the Antarctic and North
Pacific on the other. In word, it shows
that the circulation is between two points
in opposite hemispheres, and not between
the Poles and Equator. The plausibility of