Year: 1874

o,orpv,rtoYs ON BOARD THE CHALLENGER-DR.


vu II. CARPENTER FINDS HIS VIEWS CONFIRMED
.s tn THE CIRCULATION OF THE oCEAN-THE
LOWER STRATUM OF WATER FLOWING FROM


THE POLE TO THE EQUATOR WHILE THE UPPER
STRATUM FLOWS FROM THE EQUATOR 10 TIE
POLE. .


According TO Dr. William B. Carpenter, the
reseaches OF the Challenger completely bear out the
views presented by him. in regard TO the general char
acer and cause OF the circulation in the ocean In the
range between $50 N and $50 s., this conclusion being
based upon the facts asceranod In regard 10 the ther
mai stratidcation of which may be set down at


orl * o,o oOe souare miles and which has average
deot Of at least 900 feet He recaptulates his views
in the following propositions:


First That apart from the horizontal circulation pro-
duced by the action of winds upon the surface or the
ocean, there Is vertical circulation maintained In con-
sequence of the difference between the Polar and Equa-
toria areas; the whole OF water contained In any
nbasin in free communication with both, being
divided into two strata of which the lower constantly
though slowly flows the ocean-bed from the Pole
toward the Equator, while the upper Is as constantly
flowing from the Equator toward either Pole.


Second That the cause OF this circulation is the ac
ton OF surfacecod upon the water OF the Polar area
which by reducing its bulk increases Its specific gravity
down its freezing point at about 40, SO that column
Of Polar water weighs heavier than column of Equa-
torial water of the same hight This involves bottom
outflow of cold water from the Polar area, producing
general downward movement and surface indraught.
The water thus drawn in will be cooled aud will descend
in its turn On the other hand III the Equatorial area the
drawing off the surface-water aud the constant
arrival of Polar bottom will produce general up
ward movement, which, by bringing the glacial water
under the influence of solar heat will maintain differ
ence IN weight between the Polar and Equatorial
columns on which the maintenance OF this circulation
depends.


This general fact has been repeatedly Illustrated by
Dr. Carpenter by actual experiment on small scale.


Third The amelioraton Of the climate of North
Western Europe proved beyond all doubt to be do
pendent on northeast movement OF ocean water does
depend the extension of the real Gulf Stream OF
Florida current 10 the North Atlantic but is the result
OF the nOrthward movement of the whole upper stratum
in consequence OF the surface indraught toward the
Polar sea. This is shown from the fact that the great
depth of its current which, far as the Farce Islands
amounts to COO fsthOms body of water too great
to be affected by small rvulet in comparison as is
the Gulf Stream.


From these three theoretical considerations Dr. Car
penter long ago doduced the following generalization
First that in all the great basins the general Dot
tom temperature would approach that of the Polar area
in proportion TO the freedom of their communication
with IT, And in this action lie anticipated that the
bottom temperature of the South Atlantic would be
lower than that OF the North Atlantic in consequence
OF s greater freedom of communication with the Polar
area and that while the bottom temperature Of the
North Atlantic would probably not be as low as 5 ex
ep line OF the main Arctic or Antarctic under
flow that the South Atlantic wOuld probably be as
low as $50 and furthermore that the influence OF the
stronger Antarc glacial flow would very probably eX-
tend TO the north of the Equator;


Again he maintained that the depression or the bot
tom temperature would be found to depend not upon
a mere glacial stream OF few hundred feet In depth,
but upon the creeWug flow OF the whole under stratum
of from fathOms in thickness ana that hs
the Arctic and Antarctic uudernOws must meet at or
near Equator while the surface stratum Is contb-
uaIly drawn toward each Pole, there Viii be constant
ascent of glacial water under the ue showing itself by
the approach cold water TO the surface Ill tue
. intcr-tropical tnan IN the cxtratroplcai zones


finds sIgnally verified by the
temperature soundings Of the Challenger, 80 that he
feels that he j. justified In maintaining That his original
hypothesis in regard to ocean temperatures esab-
lished beyond cavil.


The upward movement OF the cold water under the
Equator according DIR. Carpenter. is Indicated Dy
distinct facts First that the Polar water s met
with much the surface than III other part OF
the area plored by the Challenger, the s0herm Of o
there lying within athoms from the surface and the
whole of water thence to tue bottom At AIS faith
Ons, where II sinks to 3I4o beng uDmstakaby polar
second that the surface temperature Is thus kept down
much lower level than reaches in shallOwer waters
inland seas where there Is 10 cold bottom water
up aud reduce IL third that the specific gravity
OF surface water OF the Equatorial band has tie low
standard which the bottom water has brought thither
from the Polar while i'll extra tropical IL Is
considerably higher, having been raised by the pro-
onged evaporation 70 which 10 has been subjected
moving toward them.