The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1874-06-15

Geography Solved by the Chsl-
lsngcr.
From the latest notes of the Challenger ex-
petition, now in the Southern hemisphere, it
appears that the thermal observations have
settled another great problem Of Antarctic
geography. The outflow Of great ocean
current from the South Indian Ocean has
long been asserted and even recently as
stoutly denied, by the physical geographers
of Europe The most recent data forwarded
by the Challenger put this matter at rest as
definitely as the much-talked-of Wilkes Ant
arctic Continent discussed in Lieutenant
Hyns's letter published in the HERALD.
The Challenger explorers state in their latest
reports published in the London Times, that
after leaving the Cape Of Good Hope they
entered the Agulhas current, and add:-"The
breadth of this stream was about two hundred
and fifty miles, and it was found to affect the
temperature of the sea to the depth OF four
hundred fathoms." We have here the dis
covered dimensions of mighty 'river in the
ocean," compared with which the Gulf Stream
of the Atlantic is but rill. The sectional
measurements of the Gulf Stream at the
Florida Pass do not exceed thirty miles in
breadth and three hundred fathoms in depth,
SO that the Agulhas current, as now gagged
by the Challenger, is nearly ten times as
large The temperature of the two oceanic
streams is about the same ]; and the velocity
of the Agulhas current is not less than that of
the mighty outflow from the Mexican Gulf.
AS the former passes the port Of Natal, it
tears violently at the shore-as the Mississippi
when in food-cutting through headlands,
carrying away small islands and creating
others with the mud it deposits.
This broad and sweeping band Of SUPER
heated water represents the collective force
of the southeast trade winds and northeast
monsoons, which blow the steaming water Of
the tropical Indian Ocean upon the East Afri-
can coast whence its only outlet is southwark,
along the Mozambique channel.
In bringing to light the thermometric
agency Of this powerful and immense current
which projects itself into the icy basin of the
Antarctic, the Challenger has unmasked the
main secrets of Antarctic meteorology and Of
the future penetrahve exploration in the South
Polar SEAS
Released from the pressure Of the easterly
winds after passing Cape Agulhas, the great
equatorial flow soon enters the realm of west
erly and northwesterly winds. The power
and regularity with which these latter winds
blow, especially in the middle 1atitudes or
'roaring forties," the Southern hemisphere,
are familiar to every Australian sea-goer.
They drive the hot streaks of Indian water
before them towards the southeast, and neces-
sarily give it an enormous thermal energy, on
course extending far into the South Polar
Basin.
The track of the Challenger, from the Cape
of Good Hope to it's highest southern latitude.
near sixty-seven degrees south and eighty
degrees east, took her outside of the warm
water. Doubtless, too, the surface of the sea
within the Antarctic circle, especially during
the summer, when the ice is rapidly melting,
is coated with thin stratum of glacier
water, serving to disguise the equatorial
stream. But the potential presence of the
latter, in the high Austral attitudes, remains
physical necessity. The Challenger observa-
tons, though partial have, it would seem,
settled the question of the thermal phenomena
of the southern hemisphere. Whatever may
be said (and, no doubt, much may be said) Of
the advantage of land exploration in the far
South, the pathway of the Agulhas current
when fully traced by the deep sea thermome-
ter, WILL as Sir James Ross found, be the best
path for the nautical survey of the South Pole.