292 Royal Society :—On the Nature of the 
the North of Scotland and the Faroe Islands. It will be recol- 
lected by those who have read my ‘ Lightning’ and ‘ Porcupine’ 
Reports on the exploration of this region, that whilst the whole 
upper stratum, from the surface to a depth of from 100 to 150 
fathoms, has the temperature of the warm flow coming up from 
the S.W., and whilst this temperature falls so gradually in the 
“‘ wari area” with increase of depth as to be still as high as 43° 
Fahr. at a depth of 600 fathoms, it falls so suddenly in the 
“cold area” between 150 and 300 fathoms, that the whole of its 
deeper stratum has a temperature below 32°, the bottom tempera- 
ture descending in some parts to 29°°5. Now on this “ cold area” 
I never found a single Globigerina, the bottom consisting of sand 
and gravel, and the Foraminifera brought up from it being almost 
exclusively those which form arenaceous tests. The “warm area,” 
on the other hand, is covered with Globigerina-ooze to an unknown 
depth, its surface-stratum being composed of perfect shells filled 
with sarcode, whilst its deeper layers are amorphous. Near the 
junction of the two areas, but still within the thermal limit of 
the “warm,” sand and G¥obigerina-ooze are mingled—this being 
peculiarly noticeable on the “ Holtenia-ground,” which yielded a 
large proportion of our most noteworthy captures in this locality. 
Now, if the bottom-deposit is dependent on the life of the surface- 
stratum, why should there be this complete absence of Globigerina- 
ooze over the “cold area,” the condition of the surface-stratum 
being everywhere the same? I was myself formerly disposed to 
attribute it to the depression of bottom-temperature ; but as it has 
now been proved by the ‘Challenger’ observations in the Atlantic 
that Globigerina-ooze prevails over areas whose bottom-tempera- 
ture is but little above 32°, this explanation can no longer be 
accepted. And I can see no other way of accounting for it than 
_by attributing it to the drift of the cold underflow, carying away 
the Globigerine that are subsiding through it towards the deep basin 
of the Atlantic, into which I believe that underflow to discharge 
itself. Prof. Wyville Thomson, however, denies any sensible 
movement to this underflow, continuing to speak of it as ‘“ banked 
up” by the Gulf-stream*, which here (according to him) has a 
depth of 700 fathoms; and this very striking example of want of 
conformity between the surface-fauna and the bottom-deposit 
consequently remains to be accounted for on his hypothesis. 
The other of Prof. Wyville Thomson’s principal conclusions, as 
to which I have rather a suggestion to offer than an objection 
to take, relates to the origin of the “red clay” which he found 
* See his ‘Depths of the Sea,’ p. 400. That there is a lateral pressure of 
the one flow against the other, just as there is a lateral pressure of the 
Labrador Current against the Gulf-stream on the North-American coast (pro- 
ducing the well-known “ cold wall ”), is sufficiently obvious from their relative 
distribution on the bottom of the channel. But it seems to me perfectly clear 
that the effect of this pressure is simply to arrow the glacial flow, and at the 
same time to increase its velocity. The most westerly poimt to which we traced 
it was near the edge of the Faroe Banks ; and there (as Prof. Wyville Thomson 
himself pointed out to me at the time) the movement of the bottom-water was 
