190 
der stiger ned og op; kun ved 
Vand ned. 
det hovedsagelig Polarvand, 
Spidsbergen stiger atlantisk 
I & 3 
Strømningerne i de forskjellige Retninger maa gjen- 
sidig compensere hverandre, naar Havets Vandmængde eller 
dets Niveau skal holde sig uforandret. De opstigende 
Strømmes Vandmasse maa være lige stor som de nedsti- 
sendes. At saa er Tilfældet, synes vel overensstemmende 
med de beskrevne verticale Bevægelser, navnlig naar vi 
tage Hensyn til den Opstigning, som finder Sted langs 
Bankernes dybere Skraaninger. I de højere Lag, hvor 
Bevægelsen foregaar ved horizontaleiStrømninger, kunne vi 
nærmere godtgjøre, at Compensation finder Sted. Fra 300 
Favnes Dyb af er Nordhavet udestængt fra Atlanterhavet. 
I denne Dybde se vi (Pl. XLIV) Vandet komme ind mel- 
lem Grønland og Spidsbergen og strømme ud mellem Grøn- 
land og Island. Afstanden mellem Isobarerne betegner de 
enkelte Strømtraades Tversnit. Mellem de samme to Iso- 
barer strømmer hele Vejen, naar Bevægelsen følger dem, 
den samme Vandmasse. Knibe Isobarerne sig sammen, 
øges Hastigheden i samme Forhold og omvendt. naar de 
Se vi nu paa Kartet, finde vi, 
at Indstrømningen ved Spidsbergen sker gjennem 3 iso- 
bare Mellemrum, og 1 Danmarkstrædet sker Udstrømnin- 
fjerne sig fra hverandre. 
gen mellem de samme Isobarer. Der strømmer ligemeget 
Vand ud af Nordhavet i dette Niveau, som der strøm- 
mer ind. 
Udføres den samme Undersøgelse for Overfladens 
Vedkommende efter Pl. XLITI, saa finder man følgende An- 
tal af Mellemrum mellem to Isobarer ved Ind- og Udstrøm- 
ningsaabningerne. 
Indstrømning. Udstrømning. 
Nordenfor Island 1 Mellemr. Danmarkstrædet 6 Mellemr. 
Færøerne til Skotland6  — Søndenfor Island? — 
Grønlandshavet 8 —  NSpidsbergen 2 — 
Novaja Semlja 5 — 
Tilsammen 15 Mellemr. Tilsammen 15 Mellemr. 
Der strømmer altsaa i Overfladen ligesaa meget Vand 
ud af Nordhavet, som der strømmer ind i det. Dette er 
af Strømkartet. Hvad Havets 
Overflade taber ved Fordunstning, faar det igjen ved Ned- 
bør, Elvevand og Isbræer. Muligens condenseres en.Del 
af det i Nordhavet fordunstede Vand først i det indre 
Polarhav, men dels kommer dette igjen ind i Nordhavet 
med Polarstrømmen, dels erstattes det ved Elvevand hid- 
rørende fra Dampe, der ere optagne paa Atlanterhavet. 
en interessant Verification 
Den Tilførsel, som Nordhavets Dyb erholder af at- 
lantisk Vand, godtgjøres ikke alene af dettes Temperatur, 
men ogsaa, som Tornøe har vist, af dets Saltholdighed og 
dets Luft- eller Kvælstofholdighed. Som ovenfor paapeget, 
er det især det søndre Bækken, det norske Hav, hvis Vand 
i Dybet for en stor Del er af atlantisk Oprindelse, om det 
end paa Grund af Berøring og Blanding med Polarvand 
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I 
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ticular is found to smk. Throughout the northern basin, 
it is chiefly Polar water that descends and rises; off Spitz- 
bergen only, Atlantic water is found to descend. 
The currents setting in different directions must com- 
pensate one another, provided the amount of water in the 
sea or its level shall keep unchanged. The discharge of water 
by the ascending currents must be equal to that by the 
And that such is the case would seem to be 
in accordance with the vertical motions described, more 
particularly if we have regard to the ascent prevailing 
along the deeper declivities of the banks. In the higher 
strata, where the motion proceeds by horizontal currents, we 
are better able to prove that compensation actually occurs. 
From a depth of 300 fathoms, the North Ocean is shut out 
from the Atlantic. At this depth, we observe (Pl. XLIV) 
the water passing in between Greenland and Spitzbergen, 
and flowing out between Greenland and, Iceland. The 
distance between the several isobars indicates the transverse 
sections of the different stream-threads. Between any two 
isobars flows, throughout the whole course, provided the 
motion proceed along them, the same quantity of water. 
descending. 
Where the isobars converge, the velocity will increase, 
and the reverse take place where they diverge. Now, if we 
regard the map, we shall observe that the influx at Spitz- 
bergen finds its way through 3 isobaric interspaces, and 
that the efflux passes through Denmark Strait between the 
same isobars. As much water flows out of the North 
Ocean at this level as flows into it. 
Supposing the same investigation, as regards the sur- 
face, to be carried out according to Pl. XLIIT, we shall 
find the following number of interspaces between two iso- 
bars at the inlet and outlet. 
Influx. Efflux. 
North of Iceland 1 Interspace. Denmark Strait 6 Intersp. 
F'æroes to Scotland 6 Interspaces. South of Iceland 2 — 
Greenland Sea 8 — Spitzbergen 2 — 
Novaja Semlja 5 — 
Total. . 15 Interspaces. ‘Total 15 Intersp. 
Hence, an equal quantity of water flows at the sur- 
face out of the North Ocean as flows into it. This is 
an interesting verification of the Current-Map. Whatever 
loss the surface of the sea may sustain by evaporation, is made 
good by precipitation, river-water, and glaciers. Possibly, 
some part of the water evaporated in the North Ocean may 
not be condensed before it reaches the inner tracts of the Polar 
Sea; but if so, this water will again be partly brought 
into the North Ocean with the Polar current, or be 
compensated by river-water originating in vapour from the 
Atlantic. 
The discharge of Atlantic water into the deep of 
the North Ocean, is not only proved by the temperature 
of the water, but also, as Tornøe has shown, by its 
salinity and content of air, or proportion of nitrogen. 
As pointed out above, it is more especially the south- 
ern basin, or Norwegian Sea, the water of which in great 
part is of Atlantic origin throughout the deep, though 
