34 
TIIK VOYAGE OF H.M.S. CHALLENGER. 
The Arctic Ocean (inclusive of the Norwegian Sea). 
'I'liis ocean is bouiuleil on the south by the Faroe Ridge, at a depth not exceeding 
•260 fathoms, extending from Iceland in a south-east direction to a point 45 miles south 
of Faroe. To this succeeds a deeper channel, the Wyville Thomson Ridge, 30 miles 
acro.'is, tlesceiuling to 380 fathoms, on the east of which commences a shorter ridge, 
with a depth of 260 fathoms, connecting it with the mainland of Scotland. Since the 
shallowest j>art of the sea from Iceland to Greenland is less than 260 fathoms, it 
follows that this ocean is a “ closed sea ” at all depths greater than 260 fathoms, except 
for tl>e short distance of 30 miles where the ridgfe sinks down to 380 fathoms. 
( hving to the prevailing south-westerly winds and accompanying current, the 
isothermals of the .surhice of the sea from 60° to 45° are pushed to higher latitudes than 
anywhere else on the globe, and it is to be remarked that the isothermals of the 
.surface water of the sea arc, for the same positions, much higher than those for the air. 
The line of maximum temperature is not close to the coast, but lies out in the Atlantic 
a ronsiderable way from the west coasts of Europe. The extension of the isothermal 
of 40° ejistwards round the north of Norway, and of the isothermal of 30° northwards 
beyond S])itzbergen, are points of great interest in connection with the distribution of 
the i.sobars and prevailing winds of this region. 
It i.s not only higher temperatures but also higher specific gravities that this great 
<K-eanic current conveys into high latitudes. Thus in the North Pacific the specific 
gravity of r0260 extends only to about lat. 33° N., and in the South Pacific, South 
.\tlantic, and Indian Ocean it just passes lat. 40° S. in a few places. In the North 
Atlantic, however, it extends as far north as lat. 72° N. and the specific gravity of 
1 ’0255 to lat. 78° N. This northern extension of the region of high temperature and 
•sj»ccifii- gravity is doubtless occasioned by the complete absence of icebergs in the 
ejustern division of this ocean. The important result is that the higher temperature of 
the surface descends to greater depths in this ocean than would otherwise be the case. 
The lowering of the specific gravities, by the rivers and rainfall, from the English 
Channel nortliwards along the west coast of Norway to Yardci is strongly marked. 
It will be ob.served that at 100 fathoms there is an area to the south-west of 
SpiizlKrrgeu, extending lus the depth incretuses, where the temperature is only 30°. This 
iM the region where the jtrevailing winds, after curving round from the south-west to 
the north-east, sweep along the fields of Arctic ice, in relation to which the course of 
the i.Hothermal of 35° is interesting. At this depth the highest temperature is close in 
‘*h»»rc to the eastward. 
The sjjccifie gravities closely follow those of the surface. The mean of ten 
ol»**ervations al>out lat. 73° N. and long. 0° to 40° E. is 1‘0258, which is very greatly in 
ex'C."a of any s|>eciric gravity observed in any ocean in similar latitudes. These, 
