8 
THE VOYAGE OF H.M.S. CHALLENGER. 
this ocean, teinporatures have been observed at fifty-five stations, the mean of these 
being 3G°‘4, or r’2 above the average, thus showing a strikingly marked difference 
lH‘t\veen the deep-sea temperature of the Indian Ocean and the South Atlantic on the 
one hand, and the Nortli Atlantic on the other. The two sections of the Pacific Ocean 
where the temperature is above the average do not show any such excess as appears in 
the North Atlantic, the exce.ss above the average being, roughly speaking, about half a 
ilegrcc. The mean of the two stations in the China Sea is 36°‘5, or 1°’3 above the 
avenige. 
In connection with deep-sea temperatures the following facts are interesting. In 
the .V retie Ocean, at a depth of 2005 fathoms. Professor Mohn observed a temperature 
of 20‘’T) in lat. G8° 21' N. and long. 2° 5' W. This position, however, is in a “closed 
area,” shut otf from the general oceanic circulation by the Wyville-Thomson Ridge. A 
little to the south of Greenland, at 1860 fathoms, 33°A has been observed; and ten 
degrees to westwards, at 1750 fathoms, 34°-0. To the east of Ceylon, at 2020 fathoms, 
:i3°-9 was observed, lat. 9° N. and long. 85° K, and to north-west of Madagascar, at 
1877 fathoms, a temperature of 33°’5 has been noted. On the other hand, to the east 
of Australia, lat. 19° S. and long. 165° E., at a dej)th of 2525 fathoms, the temperature 
was found to be 36°’4. It will be seen, when the bottom temperatures are dealt with, 
that the Atlantic stands alone among the oceans for relatively high temperatures at 
great depths. 
It is remarkable that at the depth of 2200 fathoms the water of the sea falls to its 
lowest temperature olf the east of the Argentine Coast of South America, and is nearly, 
if not (juite, at its highest ofi’ the east coast of North America, thus pointing to very 
diverse conditions in the oceanic circulation off the east coasts of these two continents. 
The striking fact is that deep-sea temperatures in all latitudes, equatorial as well as 
|)olar, are uniformly low, and, except in a few restricted regions, do not differ from each 
other more than about two degrees. The exceptional regions are where the Sea of 
tlkhot.sk meets the ocean ; the whole of the deep water immediately to the east of South 
.\merica from Caj>c St lioque to Graliame’s Land, in Antarctica; and, in a less degree, 
the southern portion of tlic Indian Ocean. It is also to be noted that the lowest deep- 
sea tcm|>eraturea are found in tho.se {)arts of tlie ocean which lie in the Southern 
hpmis|)hcre, ami that, on the whole, higher temperatures are encountered as we recede 
from the Antarctic region. It may also 1)C pointed out that the lower deep-sea 
tcmp<*rutureM extend farther to the nortli from the Soutliern Ocean, just over those 
•Icpths of the fM>a which appear to have, and probably do have, a direct communication 
with the south ; that is, are not cut off by any intervening submarine ridge separating 
them from the cold waters of .\ntarctica. 
'Diere can lie m> doubt that these very low deep-sea temperatures have their origin 
til the S<»uthcni or Antarctic Ocean, the icy-cold waters of whicli are propagated north- 
