If the Treaty of Paris in 1763 secured the Hudson's Bay Company in its monopoly of Rupert's Land, it also, by the Cession of Canada, opened to British enterprise the river-and-lake routes, discovered by the French, from Montreal to the fur-rich country west of Hudson Bay. This instalment of our list covers the years of the Montreal traders' expansion into the North-west, their crossing of the Arctic watershed into the fur trader's Eldorado, the Athabasca district, their organization into the Hudson's Bay Company's formidable rival, the North West Company, and concludes with the climax of their north-westward surge, Alexander Mackenzie's arrival at the Arctic Ocean in 1789. This activity obliged the Hudson's Bay Company to change its policy of waiting for the Indians to bring their furs to posts on Hudson Bay and made them push inland to compete for furs with the pedlars from Montreal. In the meantime, the Moravians had established missions on the coast of Labrador, searches for a North-west Passage were directed away from Hudson Bay to the Pacific coast of North America, the first scientific expedition was sent to Hudson Bay, and the Indians were decimated by smallpox. Toward the end of this instalment, we begin to draw our southern boundary of “northern Canada” both westward and northward and to omit many expeditions and events of peripheral or minor importance, such as activities south of Saskatchewan River, or of regular occurrence, such as annual voyages northward from Churchill.