CHAP. VII. ] DEEP-SHEA TEMPERATURES. oe 
perature for the last mile and three-quarters is its 
absolute uniformity, which appears to be incon- 
sistent with the idea of anything like a current in 
the ordinary sense, and rather to point to a slow 
and general indraught of cold water, falling in 
chiefly by gravitation from the coldest and deepest 
sources available, to supply the place of the warm 
water constantly moving to the northward. 
In 1870, Mr. Gwyn Jeffreys took his first tem- 
perature observations at the mouth of the Channel, 
and found them to correspond very closely with 
those of the previous year; on the 9th of July the 
bottom temperature at 358 fathoms, Station 6 PI. V., 
was 10°0C., against 9°°8 C., at about the same depth 
in a serial sounding in 1869, in the immediate 
neighbourhood. The next few soundings, Stations 
10 to 18, are in comparatively shallow water, off the 
coast of Portugal, while the next four Stations, a 
little north of Lisbon, may serve as an example of 
the temperatures to a considerable depth in that 
latitude. Station 14, 469 fathoms, with a surface 
temperature of 18°3 C., has a bottom temperature of 
10°7 C.; Station 15, at 722 fathoms, a temperature 
of 9°7C.; Station 16, at 994 fathoms, 4°4C.; and 
Station 17, at 1,095 fathoms, 4°3C. This result is 
very similar to that which we met with in 1869 off 
Ushant. With certain differences, which seem to de. 
pend mainly upon the differences of latitude, we have 
the same phenomena—a thin surface-layer, superheated 
by the direct rays of the sun; a layer of warm water 
through which the temperature descends very slowly 
down to 800 fathoms; a zone of intermixture and 
rapid descent of the thermometer of nearly 200 
