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og Differentserne ere saaledes ogsfta her vel paaviselige om
end mindre end i Overfladen. For tydeligt at kunne
markere disse optrædende Differentser paa en let overskuelig
Maade, har jeg benyttet forskjellige Farver. Saaledes ere
de Strøg, hvor Saltgehalten beløber sig til 3.50 °/0 eller
derunder, betegnede med blaa Farve, de Strøg, hvor
Saltgehalten ligger mellem 3.50 og 3.55 °/0, med rød Farve,
medens de Vandmasser, der ifølge Observationerne besidde
en Saltmængde af over 3.55 "/o, ere tegnede med en "noget
kraftigere rød Farve. I Nærheden af Kysterne er Kartet
overalt ufarvet uden Hensyn til. om Vandet der henhører
under den ene eller, den anden af de tre Hovedgrupper.
Den uregelmæssige Fordeling af Saltgehalten i de
større Dyb, som det saaledes tegnede Kart udviser, maa
unegtelig betegnes som meget paafaldende. At
Saltmængderne paa Bankerne og i clen sydlige Del af Østhavet paa
det Nærmeste findes at svare til den, som det i Overfladen
svømmende varme Atlanterhavsvand besidder, kan ikke
synes overraskende. Havet er her meget grundt, og det
deri flydende Vand besidder overalt en Temperatur af over
0" og maa saaledes nærmest henføres til den nordover
flydende Atlanterhavsstrom. med hvilken det da ogsaa helt
naturligt har Saltgehalt tilfælles. Ligeoverfor de store Dyb
maatte man derimod paa Forhaand vente et andet
Resultat. Temperaturen ligger her uden Undtagelse under 0°
ja paa de fleste Steder endog under —1°, og det kunde
derfor synes rimeligst at tilskrive det der flydende Vand
polar Oprindelse. Det fremgaar imidlertid med
Bestemthed af alle mig bekjendte Undersøgelser over
Saltmængderne i de forskjellige Have, at de fra arktiske Egne
udgaaende Strømme uden Undtagelse fører Vand af lavere
Saltgehalt end de fra de mere tempererede Himmelstrøg
udgaaende Varmvandsstrømme, og man skulde derfor i de
dybere og koldere Lag af det her undersøgte Hav vente
at tinde en Vandmasse med adskilligt lavere Saltgehalt end
den. der er funden i det i Overfladen og nærmest under
den flydende Vand. som aabenbart skriver sig fra varmere
Egne. Hvad der virkelig finder Sted er desuagtet dette,
at det i de dybere liggende Lag flydende, iskolde Vand
paa store Strækninger viser sig at have en Saltgehalt, der
temmelig nøie svarer til den, der er funden i den
atlantiske Overfladestrøm.
Saavel af denne Grund som ogsaa af andre Grunde,
som jeg senere skal fremføre, finder jeg det rimeligt at
gjøre den Antagelse, at Vandet paa de større Dyb paa de
Steder, som i Kartet tindes aflagte med rød Farve, enten
udelukkende skriver sig fra varmere Egne eller under
enhver Omstændighed er saa opblandet med saadant Vand.
at det Hele derved antager en tydelig atlantisk- Karakter,
medens Vandet i de med blaa Farve betegnede
Strækninger mere eller mindre skarpt udpræger sig som hidrørende
fra polar Oprindelse.
Hvor det gjælder at besvare Spørgsmaalet om.
hvorledes de øvre Lag finder Vei ned til Bunden, da synes
dette ikke at kunne besvares paa anden Maade, end at det
atlantiske Vand under stadig Afkjøling maa synke
gjennem det iskolde og fordrive dette, under enhver Omstæn-
cent; and there too, accordingly, the differences are
appreciable, though smaller than at the surface. For the better
apprehension of these differences, the sections in which
they occur have been differently coloured in the Plate:
blue indicates a percentage of 3.50, and under: red, a
percentage ranging from 3.50 to 3.55; and a somewhat deeper
red, a higher percentage than 3.55. Along the coasts, the
Plate is left uncoloured, no matter to which of the three
principal groups the water there belongs.
This irregular distribution of the amount of salt at
great depths, as shown in the Plate, is certainly a most
remarkable phenomenon. That the proportion of salt on
the banks and in the southern portion of Barents’ Sea
should agree pretty closely with that contained in the warm
surface-water of the Atlantic, is not indeed surprising: the
depth is in both localities comparatively trifling, and the
water, having everywhere a temperature above 0°, must
be referred to the warm Atlantic current; its percentage
of salt is therefore naturally the same as that of the Gulf
Stream. For the great depths, on the other hand,
there was reason to expect a very different result. Here,
the temperature is without exception below (J nay in most
places below —1°; and hence, as regards the origin of
such water, there seems much to urge in favour of an
indraught from the Polar Sea. Of the observations undertaken
to determine the amount of salt in sea-water, all with
which I am acquainted furnish incontestible proof that the
water of the currents flowing from the Arctic Ocean has
a lower percentage of salt than that of the warm currents
flowing from more temperate regions; and the proportion
of salt in the deeper and colder strata of the tract of
ocean explored by the Expedition was expected, therefore,
to prove considerably lower than that observed at the
surface or a short distance beneath it, where the water is
obviously an influx from warmer climes. But such was not
the case, for the amount of salt found in the water of the
cold area, where the temperature is below zero, agrees,
in some localities, pretty closely with that in the water of
the Atlanic surface-current.
This phenomenon, in conjunction with reasons that
will afterwards be explained, ■ has led me to assume, that
the water met with at great depths in the sections coloured
red in the Plate, is either exclusively the result of an
influx from warmer regions, or is. at least, so mixed with
such water as to have distinctly acquired Atlantic
characteristics; whereas the water in the blue-coloured sections
would seem to indicate more or less determinate!y a Polar
origin.
As to the question involved in the descent of the
upper strata to the bottom, the only way in which this
can take place seems to be by the Atlantic surface-water,
as it parts with its excess of heat, gradually sinking through
the water of the cold area, and displacing it; at all events,
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