754 
THE VOYAGE OF H.M.S. CHALLENGER. 
lias been divided into three parts: — 1st, the section from Japan to the 180th meridian 
on the parallel of 35^° north latitude ; 2nd, the section from the 180th meridian to the 
meridian of 156° 25' west longitude, on the 38th parallel of north latitude; and 
3rd., a meridional section from a position in lat. 38° 9' N., long. 156° 25' W., to Oahu 
Island in the Sandwich group (see Diagrams 17, 18, and 19). 
In the first part of the section the bed of the ocean shows, as had been expected 
from the soundings of the U.S. ship “ Tuscarora,” a remarkable depression in the 
immediate neighbourhood of Japan, the depth being nearly 4000 fathoms at a 
distance of 200 miles east of Nosima, after which a gradual rise takes place to 2300 
fathoms at a distance of 900 miles from that headland, then a gradual increase of 
depth to 2900 fathoms 1500 miles from Japan, and another rise to 2050 fathoms 
near the end of the section. It is probable that the deepest point of the depression off 
the Japanese coast was not hit upon, as the “ Tuscarora ” found depths of 4600 fathoms 
farther north. In the second part of the section the depths vary from 2530 to 3125 
fathoms, the mean being 2900 fathoms; whilst in the third part, south towards the 
Sandwich Islands, the bottom shows a very gradual rise until within 120 miles of the 
land, when the gradient becomes steeper. 
The temperature at the bottom was remarkably uniform throughout the whole 
distance traversed, the highest result being 35° '3, the lowest 3 4° ’8, and the mean 
35° T. The mean temperature at a depth of 1500 fathoms was also 35°T. 
These results agree with those obtained between the Admiralty Islands and Japan. 
It is therefore evident that over a very large area of the North Pacific the water 
is at a .uniform temperature from the depth of 1400 or 1500 fathoms to the bottom. 
The surface temperature on the parallel of 35-|-° N. varied from 74° to 64°‘5, the 
mean being 69°‘5. The comparatively low surface temperature of 64°'5 was exceptional, 
this result being obtained at Station 240 on the 21st June, the water remaining 
at from 6 4° ‘5 to 65° during the whole of the time sounding and trawling operations 
were carried on, although 10 miles on either side of this Station it was 5° higher 
(see Diagram 17).. 
On the 38th parallel the mean surface temperature was 65°‘3 and the extremes 
69° ‘5 and 62° '2. It would therefore appear that in the month of July a difference of 
latitude of 150 miles makes a difference of 4° - 2 in the surface temperature of the North 
Pacific on or about the 36th parallel. 
In the third part of the section, from lat. 38° 9' N., long. 156° 25' W., to 
the Sandwich Islands, the surface temperature rose gradually from 68° to 78° at 
Honolulu. 
The serial temperatures show some peculiarities. For instance, the observations 
taken at Station 240 on the 21st June, in lat. 35° 20' N., long. 153° 39' E., where 
the surface temperature was, as mentioned previously, abnormally low, gave results 
