chap, 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. Prom this point the mean depth 

 across the ocean may be estimated at about 2, ,L00 

 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." 1 



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 

 Pseroe Islands, Shetland and Orkney, Great Britain 

 and Ireland, and the bed of the North Sea to the 

 coast of Prance, 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 Eeport to the Commissioners of Public Charities and Correction 

 of the City of JN r evv York on the Chemical and Physical Facts collected 

 from the Deep-sea Eesearches made during the A^oyage of the Nautical 

 School-ship ' Mercury,' undertaken in the Tropical Atlantic and Carib- 

 bean Sea, 1870-71. Py Henry Draper, M.D., Professor of Analytical 

 Chemistry and Physiology in the University of JSTew York. Abstracted 

 in Nature, vol. v. p. 324. 



