Two or three years before D'Urville and Wilkes set out upon their voyages, Colonel Sabine, at a meeting of the British Association, read a paper on the subject of terrestrial magnetism, and the result was that Polar exploration received a great incentive. By this time the importance of terrestrial magnetism in regard to the navigation of ships was admitted, and the Government was petitioned to send a naval expedition for the purpose of increasing our knowledge of this science in the South. A favourable reply was received from Lord Melbourne, and in 1839 Sir James Ross was appointed to command an expedition whose object was rather magnetic research than geographical discovery. Two old bomb vessels, the _Erebus_ (370 tons) and the _Terror_ (340 tons), were selected by Ross, and when their bows had been strengthened he had at his disposal the first vessels that could be navigated among the Southern pack-ice. A detailed account of Ross's achievements cannot be given, but of them Captain Scott wrote: "The high mountain ranges and the coastline of Victoria Land were laid down with comparative accuracy from Cape North in latitude 71 to Wood Bay in latitude 74, and their extension was indicated less definitely to McMurdo Bay in latitude 77½.... Few things could have looked more hopeless than an attack upon that ice-bound region which lay within the Antarctic Circle; yet out of this desolate prospect Ross wrested an open sea, a vast mountain region, a smoking volcano (Erebus), and a hundred problems of interest to the geographer."* * _The Voyage of the "Discovery"_ (John Murray), page 16. The highest latitude reached by Ross was 78° 10' S., and he described the huge wall of ice which he sighted there and named the Great Barrier, as a "mighty and wonderful object, far beyond anything we could have thought of or conceived." This Barrier was in later years found to be 400 miles wide, and of even greater length. Slowly, very slowly, the Far South was being compelled to reveal some of its secrets, but in spite of the interest and enthusiasm caused by Ross's discoveries, many years passed, after his return to England in 1843, before further steps were taken to make geographical discoveries in the Antarctic.