REPORT ON OCEANIC CIRCULATION. 
7 
temperatures below it by black lines. These lines thus show graphically for each 
depth the regions where the temperature is above the average for that depth and where 
it is below it. 
The most striking fact revealed by deep-sea observations of temperature is the very 
low temperature of the ocean at great depths in all latitudes, this being but a little way 
above the freezing-point of fresh water. To show this feature more exactly, a map 
was constructed indicating the temperature at the depth of 2200 fathoms. The average 
of all the observations made at this depth give a mean temperature of 35 0, 2. Another 
map has been constructed (Map 14) on which are entered the differences of the 
individual temperatures from this average, those which exceed it being entered in 
red ink, and those under it in blue ink. The result is interesting and instructive. 
Everywhere over the Indian Ocean temperatures at 2200 fathoms are under the 
mean. There are twenty observations whose mean temperature is 34°’4, being thus 0 o, 8 
lower than the general ocean at this depth. Over the whole of the South Atlantic to the 
south of lat. 10° S. temperatures are also under the mean, slightly in the eastern side of 
the ocean but very largely in the south-west of it. At three stations to the east of Buenos 
Ayres between longitudes 35° and 45° west the temperature is only 32 0- 6, which is the 
lowest yet observed in any part of the ocean not within a “ closed area ” ; that is, in a 
position shut off by submarine ridges from the general oceanic circulation. It is highly 
probable that temperatures even lower may yet be observed off Cape St. Roque, where 
32 0, 2 has been observed at a depth of 2537 fathoms. Temperature is also under the 
mean over the whole of the Pacific Ocean, except (l) to westwards of a line drawn 
from the south and west of Japan to the north of New Zealand ; and (2) over a large 
section of that ocean enclosed within a line passing from Valparaiso and curving round 
by about Marquesas Islands to Acapulco, though it must here be stated that 
observations are wanting from Valparaiso to Galapagos in and over the central parts of 
this region. Future soundings will probably show that these are areas shut off by a 
low enclosing ridge at the bottom. The lowest temperature in the Pacific is 33° - 2, or 
2 o, 0 under the mean, a little to the south of Kamtschatka. Temperatures nearly a 
degree under the mean have been observed off Alaska, San Francisco, to the north-east 
of New Zealand, and in about lat. 40° S. and long. 107° W. But throughout the 
cold area of the Pacific generally the deficiency below the mean temperature of 
the oceans is extremely small. Thus, leaving out the small areas where temperature is 
nearly a degree under the mean, the mean temperature of the remaining sixty-three 
stations is 35 o- 0, or only 0 o, 2 under the mean temperature of the whole ocean at that 
depth. Speaking generally, the temperature of the Pacific at 2200 fathoms closely 
approximates to the average of the ocean taken as a whole at this depth. 
The temperature of the North Atlantic is everywhere above the average of the 
whole ocean, and the amounts of excess are for the great depths in all cases large. In 
