cmap, v.] DEEP-SEA SOUNDING. 233 
“parting from the African coast, the bed of the 
ocean sinks very rapidly. <A couple of degrees west 
of the longitude of Cape Verde the soundings are 
2,900 fathoms. From this point the mean depth 
across the ocean may be estimated at about 2,400 
fathoms, but from this there are two striking 
departures—first, a depression, the depth of which 
is 3,100 fathoms; and, second, an elevation, at which 
the soundings are only 1,900, the general result of 
this being a deep trough on the African side and a 
narrower and shallower trough on the American.”’ ! 
Referring to the chart (Pl. VII.), in which the 
greater depths are indicated by the deeper shades of 
blue, a shade to every 1,000 fathoms; in the Arctic 
Sea there is deep water ranging to 1,500 fathoms to 
the west and south-west of Spitzbergen. Extending 
from the coast of Norway and including Iceland, the 
Firoe Islands, Shetland and Orkney, Great Britain 
and Ireland, and the bed of the North Sea to the 
coast of France, there is a wide plateau on which the 
depth rarely reaches 500 fathoms, but to the west of 
Iceland and communicating doubtless with the deep 
water in the Spitzbergen Sea a trough 500 miles wide 
and in some places nearly 2,000 fathoms deep, 
curves along the east coast of Greenland. This is 
the path of one of the great Arctic return currents. 
1 Cruise of the School-ship ‘ Mercury’ in the Tropical Atlantic, with 
a Report to the Commissioners of Public Charities and Correction of 
the City of New York on the Chemical and Physical Facts collected 
from the Deep-Sea Researches made during the Voyage of the Nautical 
School-ship ‘ Mercury,’ undertaken in the Tropical Atlantic and Carib- 
bean Sea, 1870-71. By Henry Draper, M.D., Professor of Analytical 
Chemistry and Physiology in the University of New York. Abstracted 
in Nature, vol. v. p. 324. 
