The Columbia herald. [volume] (Columbia, Tenn.) 1850-1873, 1873-08-22
VOL. XIX. NO. 6.
Physical aeography Of the Sea.

Physical Geography of the Sea.
Though it is true that sea-water stead
lily contracts as it cools down TO its
freezing-point, instead of expanding be-
! fore it reaches its freezing-point as fresh
\ water does, the truth has been steadily
| ignored by even the highest authorities
in physical geography, and the erron-
| eous conclusions deduced from their
erroneous premises have been widely
accepted as If they were ascertained
| facts. OF course, if sea-water, like
| fresh water, were heaviest at tempera-
| ture of 80 degrees Fahrenheit, and got
| lighter as it approached 80 degrees, the
| water of the bottom of the deep sea
could not be colder than 80 degrees.
But one of the first results of the care
full ascertainment of the temperature at
different depths, by means of thermo-
meters specially contrived for the avoid
ance of the errors produced by pres
sure, was the proof that, below 1000
fathoms in the Atlantic, down TO the
greatest depths yet sounded, the water
has temperature yet lower than 3S de-
grees Fahrenheit, whatever be the tenn
perature of the water at the surface.
And that this low temperature of the
deepest water is probably the universal
rule for the depths of the open ocean is
shown, among others, by Capt CHM
mos recent observations in the Indian
ocean, between Ceylon and Sumatra,
where the surface-water ranging from
S5 degrees to 81 Fahenheit the tempera-
ture at the bottom, at depth of 2,27O
to 2, 656 fathoms, was only from 81 de-
- 1aoroac EaarpnhnIt
As the mean temperature of the super
fetal LAYER of the crust of the earth
may be taken at about 80 degrees Fab
renheit, il follows that the bottom layer
of the deep sea in temperate and hot
latitudes is, on the average, much colder
than either of the bodies with which it
is in contact; for the temperature of
the earth is constant, while that of the
air rarely falls so low as that of the bot
tom water in the latitudes in question
and, even when it does, has time to
affect only comparatively thin stratum
of the surface-water before the return
of warm weather.
How does this apparently anomalous
state of things come about? II we sup
pose the globe to be covered with uni
versal ocean, it can hardly be doubted
that the cold of the regions toward the
poles must tend to cause the superficial
water of those regions to contract and
become specifically heavier. Under
these circumstances it would have no
alternative but to descend and spread
over the sea bottom, while its place
would be taken by warmer water drawn
from the adjacent regions. Thus deep,
cold, polar-equatorial currents and SUI
perfcial, warmer, equatorial-polar cur
rents would be set up; and, as the
former would have a less velocity OF ro-
tation from west to east than the regions
toward which they travel, they would
not be due southerly or northerly cur
rents. but southwesterly in the northern
hemisphere, and northwesterly in the
southern; while, by parity of reason
ing, the equatorial-polar warm currents
would be northeasterly in the northern
hemisphere, and southeasterly in the
southern. Hence, as northeasterly
current has the same direction as a
south-westerly wind, the direction OF
the northern equatorial-polar current in
the extra-tropical part of its course
would pretty nearly coincide with that
of the anti-trade winds. The freezing
of the surface of the polar sea would
not interfere with the movement thus
set up. For, however bad a conductor
of heat ice may be, the unfrozen sea
water Immediately in contact with the
under surface of the ice must needs be
colder than that further off and hence
will constantly tend to descend through
the subjacent warmer water.
In this way it would seem inevitable
that the surface-waters of the northern
and southern frigid zones must, sooner
or later, find their way to the bottom of
therest of the ocean and there accumu-
late to a thickness dependent on the
rate at which they absorb heat from the
crust of the earth below, and from the
surface-water above If this hypothesis
be correct, it follows that, if any part
of the ocean in warm latitudes is shut
off from the influence of the cold polar
underhow, the temperature of its
depths should be less cold than the
temperature of corresponding depths in
the open sea. Now, in the Mediter-
ranean, nature offers a remarkable ex-
perimental proof of just the kind
needed. 1t is land-locked sea, which
runs nearly east and w st, between the
twenty-ninth and forty-fifth parallels Of
north latitude. Roughly speaking, the
average temperature of the air over it is
rs degrees Fahrenheit in July, and As
degrees in January.
The great expanse of water is divided
bv the peninsula of Italy, including
Sicily. continuous with which there is
submarine elevation carrying less than
/ 200 feet of water, which extends from
Sicily to Cape Bon, in Africa, into two
great pools, an eastern and a western.
The eastern pool rapidly deepens to
more than $4,000 feet, and sends off to
the north its comparatively shallow
branches, the Adriatic and the Hgean
seas. The western pool is less deep,
though it reaches some 10000 feet.
And. lust as the western end of the east
ern pool communicates by a shallow
passage. not sixth of its greatest
depth, with the western pool so the
western pool is separated from the At
Iantic by a ridge which runs between
capes Trafalgar and Spartel, on which
there is hardly / 200 feet of water All
the water of the Mediterranean which
lies deeper than about $50 fathoms,
therefore, is shut off from that of the
Atlantic, And there is no communuca-
ton between the cold layer of the At
lantic, below 1000 fathoms, and the
Mediterranean. Under these circum-
stances, what is the temperature of the
Mediterranean? Everywhere below GOO
feet it is about 55 degrees Fahrenheit
and consequently, at its greatest depths,
it is some 90 degrees warmer than the
corresponding depths of the Atlantic.
1t seems extremely difficult TO account
for this difference in any other way
than by adopting the view so strongly
and ably advocated by DIR. Carpenter,
that, in the existing distribution of
land and water, such circula-
ton of the water of the ocean does
actually occur, as theoretically must
occur, in the universal ocean, with
which we started.-Prof T. III. Hurley.
Mrs. Swisshelm claims that the eedu-
Gated Indians who return to their tribes
become vagabonds. Hole-in-the-Day
permitted his son and heir to be taught
in a mission-school at st. Paul, where
he became a good English scholar and
dandy. Government built him six
room frame cottage, which his tribe
finally burned, but in which he lived
MANY wears of elegant leisure with his