The herald and mail. [volume] (Columbia, Tenn.) 1873-188?, 1875-10-22

occurred to me why the surface-stratum
should contain so small measure of heat.
And vet, on reasoning out this problem,
7 came to see that, anomalous as it may
seem, the wanto of communication between
the North Pacific and Arctic basins, in
the presence of perfectly free communi-
cation with the antarctic, is reason why
the upper stratum of the former should
be rather colder than warmer. For we
NAV consider the entire Pacific and Ant
arctic basin in the light of a long trough,
at the south end of which polar cold is
applied to the surface; while equatorial
heat is applied at, say-One third of the
length of the trough, from the north end.
Now, in the southern division of the
trough, the circulation will go on as IN
the former case: the water chilled by polar
cold descending and flowing along the
floor of the trough, and being replaced
by the surface inflow of warmer water
from the equatorial region. But as the
polar bottOm-fow will not meet any SIM
liar flow from the opposite end of the
trough, only portion of it will rise to
the surface under the equator, the re-
mainder continuing to flow to the north
ern end of the trough, thus keeping its
temperature down nearly to the antarc-
tic standard. On the other hand, the
sOuth-p6lar surface-indraught will not
only extend to the Equator, but, i'll the
absence of any corresponding indraught
towards the north pole, will act back
wards Gas it were) upon the upper stra-
tum of the North Pacific, giving it a
southwark movement towards the equa-
tor, instead of the nOrthward movement
from the equator, which is so remarka-
bic feature of the Atlantic. To re-
place this. the cold under-stratum of the
North Pacific will be continually rising
towards the surface; and thus the pow
erfll action of the suns summer heat
between the parallels of 800 and so, viii
be constantly antagOnized by that of the
winter cold of the antarctic area at
distance of eight thousand miles or more.
But if a subsistence of the land border
ing Behring's Strait were to take place to
such an extent as to open a broad and
deep channel between the North Pacific
and the arctic basin, the outflow of
polar water that would then go on from
the latter into the former, would produce
a movement of the upper stratum in the
contrary direction; thus drawing a sur
face-fOw of equatorial water towards
the Aleutian Islands, and raising the
temperature of the land-border on either
side.
Thus we see the great importance Of
this general oceanic circulation in regu-
lating the distribution of temperature,
alike at the surface and over the bottom,
of those vast marine areas, which, in the
aggregate, cover little less than three
fourths of the whole superfcies of our
globe. And it is by this distribution of
temperature, that the distribution of
animal life is mainly dominated. But as
| showed on a former occasion (VOl. xxi.
p. 39D, its influence in providing the
inhabitants of the abyssal waters, with
both food and oxygen Is not one whit less
important; the condition of a deep in
land sea (such as the Mediterranean,
which is virtually cut off from its infu
ence, being one of such stagnatiOn, as to
be incompatible with the existence of
animal life at any great distance beneath
the surface. There is no reason to sup
pose that animal life could exist on the |
ocean-bottOm at depths far exceeding
that of the barren sea-bed of the Med |
iteTranean, if it were not for the vertical |
produced by opposition of
which, by bringing up
every drop of ocean-water, in its turn,
from the deepest abysses to the surface,
purifes it from the carbonic acid and |
other products of animal decomposition
with which it has come to be charged, |
imparts to it a vivifying dose of oxygen,
and mingles with it those products of |
life, which serve, when carried |
down to the ocean-depths, for the nu-
triton of the animals that swarm upon |
their bottom, and contribute, by the |
accumulation of their calcareous eluui0, |
to form the cOmponents of future con-