succeeded in making the first sounding beyond the edge of the 

 continental shelf in a basin between Iceland and Norway. Following 

 is a description of the method he used : 



"September the fourth, at two in the afternoon, we sounded with 

 all the lines, above eight hundred fathoms. Some time before the 

 last line was out, we perceived a slack, and that it did not run off 

 near so quick as before. When we got the lines in again, the first 

 roll came in very easily and twenty fathoms of the next, after which 

 it took a great strain to move the lead; a mark was put on at the 

 place where the weight was perceived and the line measured, by 

 which the depth was found to be six hundred and eighty-three 

 fathoms. The lead weighed above one hundred and fifty pounds, 

 and had sunk, as appeared by the Une, near ten feet into the ground, 

 which was a very fine blue soft clay." 



Not only did Captain Phipps get a depth measurement, but he 

 also got a sample of the bottom, and with thermometers attached 

 to the line he was able to take a temperature measurement of the 

 deep water. His sounding of 683 fathoms is still on Admiralty charts 

 today. But a half century or more passed before oceanographers 

 found the bottom far out in the oceans. In some attempts they 

 paid out as much as six thousand fathoms of line before they 

 reached bottom, but they soon discovered that currents and surface 

 winds, by carrying the ship far off to the side, were giving them an 

 exaggerated reading. 



Sir James Clark Ross, who voyaged to the Antarctic in 1840, 

 solved this problem by sounding from an open boat that was held 

 in position against wind and surface current by a second rowing 

 boat. He had a sounding line four miles long wound on a large 

 drum that allowed a weight to pull the line off freely. By carefully 

 timing each successive one hundred fathoms of paid-out line, he 

 was able to mark the change of speed when the weight hit the 

 bottom. His sounding, made in the South Atlantic (lat. 27°26'S., 

 long. i7°29'W.) established an accurate depth of 2425 fathoms. 

 The whole operation, including recovery of the weight, took about 

 four hours. 



Around this time talk of laying a trans-Atlantic submarine tele- 

 graph cable stimulated a great wave of effort to find out about the 

 depths of the ocean. As a result, sounding techniques were stream- 

 lined: detachable weights rather than fixed ones eased recovery of 

 the line; wire lines replaced rope lines; and a steam-powered winch 

 was used for reeling in. The expedition of H.M.S. Challenger around 

 the world, between 1872 and 1876, returned with an impressive 

 collection of deep-sea soundings. With this new data cartographers 

 finally were able to draw charts showing several main features, 

 such as basins and mountain ranges of the ocean bottom. The 

 expedition also brought back new information about the sediments 

 that range over the sea floor. Since the three-year Challenger voyage, 

 which laid the foundation of modern oceanography, many other 

 expeditions have studied particular problems and particular areas; 

 but when we consider the giant size of the oceans and the many 

 difficulties of peering and probing into them, all the work that we 

 have done to date seems a mere skeleton which has yet to be 

 clothed in flesh. 



The submarine geologist now has an impressive battery of new 

 instruments and techniques for exploring the deep-ocean floor and 



Ross took soundings from an open boat held 

 in position against wind and surface 

 currents by a second boat, l-iis sounding line, 

 wiiicii was paid out and recovered by a 

 rotating drum, was four miles long. 



An engraving of tiie Great Eastern battling 

 a heavy sea as she lays the first 

 transatlantic cable. June 30, 1866. 



191 



