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Proceedings of the Royal Society 
upper surfaces were covered with a coating of peroxide of man- 
ganese, and had living serpulse attached. The line to which a stone 
was imbedded in the deposit was sharply marked by the manganese 
deposit. It would seem as if currents existed here towards the 
north-east strong enough to carry fine mud away from the top of the 
ridge, and to leave the larger stones exposed, or at least strong 
enough to prevent a deposit of fine mud from forming. 
It is worthy of remark that we dredged no large stones in either 
the cold or warm area, some distance away from the ridge. 
In the deposit of the warm area the average size of the mineral 
particles is only '15 m.m., and these are nearly all angular fragments 
of quartz, fellspar, &c., but no fragments of the ancient rocks of the 
north of Scotland of sufficient size to be detected. In the cold area 
the mean diameter of the mineral particles is '35 m.m., with many 
larger fragments of Cambrian (?) sandstone, mica schist, amphibolic 
gneiss, &c. (see description of deposits, pages 29-33). 
3. Temperature . — The serial temperatures show that from the 
surface to a depth of a little over 200 fathoms the temperature of 
the water is nearly the same over both the warm and cold areas, but 
at greater depths there are wide differences. 
Similar results were obtained by the “Porcupine” in 1869. 
It is very probable that throughout the winter, the temperature at 
the sea surface and to the depth of 200 fathoms in this vicinity, is 
from 48° to 49°. This temperature is much warmer than that found 
in the same latitude in any other part of the North Atlantic. It is 
evidently, therefore, not derived from the locality or from a more 
northern source, but certainly comes from a southern latitude. 
For these reasons we believe that the whole body of water on the 
south-western side of the Wyville Thomson Eidge is moving toward 
the north-eastward, and that the layers deeper than 200 fathoms are 
stopped or deflected, when they come in contact with the ridge, 
while those less deep than 200 fathoms flow onward to the north- 
eastward. 
The cold water, which fills the deeper part of the basin to the 
N.E. of the ridge, must come from the Arctic Ocean. 
Here we would point out a peculiarity in the distribution of 
temperature in the Faroe Channel, a peculiarity not met with in any 
of the regions examined during the “ Challenger ” expedition. 
