The record-union., 1897-01-24

larged, to make the best of the faint
light which may possibly penetrate
there. After 1000 fathoms these
organs are either still further enlarged.
or so greatly reduced that in some
species they disappear altogether and
are replaced by enormously long feelers.
The only light at great depths which
would enable large eyes to be of any
service is the phosphorescence given out
by deep-sea animals. We know that
at the surface this light is often very
powerful, and Sir Wyville Thomson has
recorded one occasion on which the sea
at night was "a perfect blaze of phos-
phorescence, SO strong that lights and
shadows were thrown on the sails and it
was easy to read the smallest print" 1t
is thought possible by several natural
lists that certain portions of the sea bot
tom may be as brilliantly ilIumined by
this sort of light as the streets of
European city after sunset. Some deep
sea fish have two parallel rows of small
circular phosphorescent organs running
along the whole length OF their bodies,
and as they glide through the dark
waters of the profound abysses they
rows of shining portfolios.
THE WARM STRATUM.
1t was at one time held that the tenn
perature of the ocean never descended
lower than 50 degrees Fahr., but this
unfounded assumption was disproved
by the Challenger expedition. AS low
a temperature as q degrees has been
obtained in the South Atlantic in the
neighborhood of icebergs. The freez-
ing point of salt water is % degrees
Fahr., and the fact that it contracts
steadily down to the freezing point in
stead of expanding again like fresh
water when within 4 degrees of it,
causes the coldest water to sink always
to the bottom. In a sounding of 2.9Oo
fathoms taken in the South Atlantic, the
bottom temperature was 81 degrees. and
the last 1000 fathoms might be de-
scribed as absolutely glacial. The sec
ond 1000 fathoms consisted of water
from 80 to 3612 degrees, and in the
course of the next 800 fathoms the tenn
perature rose to 40 degrees. The re-
naming 400 fathoms constituted the
warm upper stratum of water, ~ de-
grees being the limit at which the suns
rays exert any direct heating influence
In the North Atlantic no lower tenn
perature than 80 degrees is found. and
the warm stratum, instead of being only
400 fathoms, is 800 or 900 fathoms deep.
One reason for this comparatively high
temperature is that a ridge runs at the
bottom of the sea right across the ocean
from Greenland to Norway, rising above
IL, nd ri
is of such a hight that the deeper and
colder parts of the Arctic basin are un-
able to communicate with the North At
lantic. DR.. Nansen states that the
soundings taken by the Fran, while
drifting with the ice, gave a depth of
between 500 and ! 900 fathoms and
he thinks that the whole Polar basin
should be considered as a continuation
of the deep channel which runs between
SpitZbergen and Greenland from what
he calls the North Atlantic Ocean. In
Norwegian charts the North Atlantic
may reach as far as Spitzbergen, in
stead of terminating, as in English
charts, at the latitude of Iceland But
as the doctors words are liable to mis-
Interpretation, it is as we'll to point out
that no deep channel exists connecting
the Arctic Ocean with the main portion
of the North Atlantic Ocean.
The increased depth of the warm
stratum is also due to the fact that the
waters of tropical latitudes have been
heated by the Gulf Stream or Florida
current. The Gulf Stream itself dies
out in midAtlantic, losing it's move
ment, warmth and deep color, and be-
coming mere surface drift But the
ocean water it has heated. gaining
greater specific gravity under the evap-
Grating action of the dry trade winds
sinks downward, and, mingling with
the cooler water below, extends the
depth of the warm stratum to 500 or 900
fathoms. The warm stratum is then
carried northward by the vertical circu-
lation of the ocean, the cold bottom
water from the poles rising near the |
equator, and the warm surface water |
from the equator sinking near the poles
This action is atteSted by the fact that |
the plane of 10 degrees of temperature |
rises at the equator from 700 to only |
800 fathoms from the surface.-Nine- |
teenth Century.