Various tracts of land have been discovered near the Antarctic Circle, and within it, though none in so high a latitude as Victoria Land. Whether they form part of one large continent remains to be ascertained. Discovery ships sent by the Russian, French, and American governments have increased our knowledge of these remote regions, and the spirited adventures of British merchants and captains of whalers have contributed quite as much.[90] The land within the Antarctic Circle is generally volcanic, at least the coast-line, which is all that is yet known, and that, being covered with snow and ice, is destitute of vegetation. [The land described by Sir James Ross as Victoria Land, was, in fact, discovered by the U. S. Exploring Expedition, under the command of Charles Wilkes, Esq., U. S. Navy. He says:—“That land does exist within the Antarctic Circle is now confirmed by the united testimony of both French and English navigators. D’Urville, the celebrated French navigator, _within a few days after land was seen by the three vessels of our squadron_, reports that his boats landed on a small point of rocks, at the place (as I suppose) which appeared accessible to us in Piner’s Bay, whence the Vincennes was driven by a violent gale; this he called Clarie Land, and testifies to his belief of the existence of a vast tract of land, where our view of it has left no doubt of its existence. Ross, on the other hand, penetrated to the latitude of 79° S. in the succeeding year, coasted for some distance along a lofty country connected with our Antarctic Continent, and establishes beyond all cavil the correctness of our assertion that we have discovered, not a range of detached islands, but a vast Antarctic Continent. How far Captain Ross was guided in his search by our previous discoveries will best appear by reference to the chart, with a full account of the proceedings of the squadron, which I sent to him, and which I have inserted in Appendix XXIV., and Atlas. Although I have never received any acknowledgment of their receipt from him personally, yet I have heard of their having reached his hands a few months prior to his Antarctic cruise.”]— _Wilkes’s “Narrative of the U. S. Exploring Expedition,”_ vol. ii., p. 281-2. CHAPTER XV. Nature and Character of Mineral Veins—Metalliferous Deposits—Mines—Their Drainage and Ventilation—Their Depth—Diffusion of the Metals—Gold— Silver—Lead—British Mines—Quicksilver—Copper—Tin—Cornish Mines—Coal— Iron—Most abundant in the Temperate Zones, especially in the Northern— European and British Iron and Coal—American Iron and Coal—Arsenic and other Metals—Salt—Sulphur—Diffusion of the Gems.