26 
THE VOYAGE OF H.M.S. CHALLENGER. 
Guinea five observations give a mean specific gravity of 1*0245. It is scarcely 
necessary to remark that these still point to the influence of the Mediterranean. 
The temperature relations of the South Atlantic and the Pacific are unchanged. In 
the North Pacific ten observations give a mean specific gravity of 1 ‘0255, and in the 
South Pacific fifteen observations also give a mean of 1*0255, which very well accords 
with the equable distribution of temperature over this ocean. The region of the low 
temperature to the north-east of Australia is only half a degree lower than surrounding 
temperatures. 
Depth of 900 Fathoms (Map 11).—The mean temperature at this depth is 36°'8, 
having fallen half a degree from 800 fathoms. The highest temperature, 42°, is still to 
westward of Gibraltar, from which the temperature steadily falls westwards in the same 
manner as at the depths of 500, 600, 700, and 800 fathoms, but only to the extent 
of 2°. In the South Atlantic temperatures are relatively higher, and in the Pacific 
there is a tendency towards an equalised temperature more than in any of the other 
oceans. The high specific gravities of 1*0269 and 1*0264 were observed to the west 
and south-west of Gibraltar, which are not approached anywhere else, the highest of 
the thirteen observed between lat. 10° N. and 10 S. being 1*0259 and the mean 1*0256. 
It may be added that a specific gravity of 1*0271 has been recorded to the north¬ 
east of the Galapagos Islands in the region of the highest temperature of the Pacific at 
this depth. 
Depth of 1000 Fathoms (Map 12).—From 900 to 1000 fathoms the mean 
temperature has only dropped 0°*3, being now 36°*5. The distribution of temperatures 
and specific gravities continues much the same over the oceans, the North Atlantic, 
looked at as a whole, showing the highest temperature, then follow in order the South 
Atlantic, the South Pacific, and finally the North Pacific. 
There is still a trace seen of the influence of the Mediterranean. With respect to 
the high temperatures, so marked a feature of this part of the ocean from 500 to 
1000 fathoms, it is to be remarked that they are not part and parcel of any great 
surface oceanic current, but simply an illustration of a slow vast movement of the waters 
of the ocean wholly due to differences of specific gravity of these waters. 
Dep>th of 1500 Fathoms (Map 13).—From 1000 to 1500 fathoms temperature has 
fallen 1°*2, the mean being 35°*3, The highest temperatures are :—In the North Atlantic, 
38°; South Atlantic, 37°*5 ; North Pacific, 36°*5; and South Pacific, 36°; there being now 
onl} 7 2° between the highest and lowest of these. A noticeable feature is that the North 
and South Atlantic have now nearly the same temperature. The western half of 
the Atlantic, from lat. 10° N. southwards, has a temperature decidedly lower than the 
eastern half. 
But while the mean fall of the temperature of the whole ocean is only 1°*2, it is 
larger in the Atlantic. Thus averaging all the observations, the means of the North 
