CHAP, v.] DEEP-SEA SOUNDING. 231 



have been prosecuting a most careful and elaborate 

 survey of their coast-line ; and latterly the Coast 

 Survey, under the late Professor Bache and the pre- 

 sent energetic head of the Bureau, Professor Pierce, 

 has pushed its operations into deep water, particu- 

 larly in the Gulf-stream region north-vrestwards of 

 the Strait of Florida. Dredging operations have 

 been conducted most successfully under Count Pour- 

 tales, and it will be seen hereafter that his results 

 are a valuable complement and corroboration of our 

 own. The Swedish Government has twice executed 

 careful soundings in the sea between Spit zber gen and 

 Greenland and to the south-west of Spitzbergen ; in 

 1860 under the direction of Otto Thorell, and in 

 1868 through the Swedish Arctic Exploring Expe- 

 dition under Captain Count von Otter of the Royal 

 Swedish steamer ' Sophia.' In 1869 the Swedish 

 corvette ' Josephine ' sounded and dredged in the 

 North Atlantic, taking soundings to the depth of 

 upwards of 3,000 fathoms, and discovered the ' Jose- 

 phine Bank,' with a minimum depth of 102 fathoms, 

 in lat. 36° 45' N., long. 14° 10' W. to the north-west 

 of the Strait of Gibraltar. The North-German Polar 

 expeditions greatly increased our knowledge of the 

 Spitzbergen and the Greenland Seas ; and finally, 

 on December 20th, 1870, the American nautical 

 school-ship ' Mercury,' Captain P. Giraud, crossed the 

 Tropical Atlantic to Sierra Leone, which she reached 

 on the 14th of Eebruary, 1871. She left Sierra 

 Leone on February 21st, and soundings and other 

 observations were continued till she reached Havan- 

 nah on the 13th of April. The object of this ex- 

 pedition and the character of the observers are 



