Cook's careful circumnavigation of the world in high southern latitudes established the perimeter within which the still theoretical Antarctic continent might be found. In the seven decades after Cook, a succession of voyages located Antarctica. And although its continental status remained conjectural until the early twentieth century, these voyages identified it as a large landmass or archipelago, and named and claimed parts of its coastline and islands. The logic of southward exploration that led to this important phase of Antarctic exploration was initially generated by the broader structural coevolution of capitalism and colonialism. Cook's account of his Antarctic expedition was published in 1777, and its reports of vast numbers of Antarctic fur seals on the island of South Georgia directed the attention of the burgeoning sealing industry towards Antarctic waters from 1786. Sealing led to the discovery of the South Shetland Islands (1819–21), the first landing on the Antarctic continent, and the voyages of sealer-explorers James Weddell (1822–4), John Biscoe (1830–2) and John Balleny (1838–9). The growth of the industry combined with colonial expansion and embryonic national rivalry, to generate expeditions from Tsarist Russia (Bellingshausen, 1819–21), post-Napoleonic France (d'Urville, 1837–40), the United States (Wilkes, 1838–42) and Britain (Ross, 1839–43). As in the earlier period, science, commerce and exploration were often interlinked – sealers like Weddell or Balleny carefully recorded natural and scientific data as they searched for seals; conversely explorers like d'Urville and Ross reported on the economic potential of the places they visited.