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POPULAR SCIENCE REVIEW. 
and probably approach near the water surface somewhere about 
latitude 55° N. and longitude 30° E., where according to old 
accounts there was once land. The telegraph plateau, as it is 
called — the line of sea bottom on which the first Atlantic 
telegraph was successfully laid — lies a little to the south of 
this bank and is much deeper. To the north there is the Arctic 
Ocean covered most part of the year by ice, and only com- 
municating occasionally with the Pacific Ocean by narrow 
choked up channels. To the south there is the Gulf Stream, a 
current of warm water, at the surface certainly approaching 
mid- Atlantic, whatever may be its extension towards the shores 
of Europe. Warm water is brought in this way across the 
Atlantic steadily, incessantly, and in large quantities, and it is 
quite impossible that the drag of this great stream-current 
should not even by mere friction produce a current of some 
depth. It is certain that in some places the warm current 
reaches the actual sea bottom. 
Recent observations have shown that besides this warm 
current reaching the latitude of 50°, the part of the Atlantic 
canal we have alluded to above is affected by certain causes 
which produce real and well-defined currents, some near the 
surface, some near the bottom, some warmer than the mean 
temperature of the air above, and some cooler. There are 
broad and deep warm currents running from south-west to 
north-east, and other broad and deep cold currents running 
from north-east to south-west, and this complication of currents, 
influenced, there cannot be a doubt, by the form of the sea 
bottom, appears to have produced certain natural history results 
which are of the most extraordinary significance with reference 
to the geological question we are considering. It is in this 
respect, perhaps more than any other, that the value of recent 
observations concerning deep sea temperature must be measured. 
That there is an important arctic drift running down along 
the coast of Greenland, conveying ice occasionally, and for 
some cause turned northward at the southern extremity of 
Greenland into Davis’s Straits, has been long known. It is this 
current that renders Greenland almost uninhabitable, in latitudes 
where in Norway and Sweden we have a very pleasant climate 
and a large population. The cold or arctic current runs 
between the west coast of Iceland and the east coast of Green- 
land. (See Chart in Plate.) There are also powerful cur- 
rents at a very low temperature proceeding through Hudson’s 
Straits, entering the Atlantic near Newfoundland, and crossing 
the warm Gulf Stream. 
One part of the great arctic current running along the east 
coast of Iceland passes down into the Atlantic to the south-west 
and is there soon lost. Another part, however, still further to 
