By the Treaty of Paris in 1763 the whole of French America was ceded to England, which also obtained possession of Florida from Spain, in exchange for the Philippines, captured during the war. As a compensation all the country west of the Mississippi became joined on to the Spanish possessions in Mexico. These of course became, nominally French when Napoleon's brother Joseph was placed on the Spanish throne, but Napoleon sold them to the United States in 1803, so that no barrier existed to the westward spread of the States. Long previously to this, a Chartered Company had been formed in 1670, with Prince Rupert at its head, to trade with the Indians for furs in Hudson's Bay, then and for some time afterwards called Rupertsland. The Hudson Bay Company gradually extended its knowledge of the northerly parts of America towards the Rocky Mountains, but it was not till 1740 that Varenne de la Varanderye discovered their extent. In 1769-71 a fur trader named Hearne traced the river Coppermine to the sea, while it was not till 1793 that Mr. (after Sir A.) Mackenzie discovered the river now named after him, and crossed the continent of North America from Atlantic to Pacific. One of the reasons for this late exploration of the north-west of North America was a geographical myth started by a Spanish voyager named Juan de Fuca as early as 1592. Coasting as far as Vancouver Island, he entered the inlet to the south of it, and not being able to see land to the north, brought back a report of a huge sea spreading over all that part of the country, which most geographers assumed to pass over into Hudson Bay or the neighbourhood. It was this report as much as anything which encouraged hopes of finding the north-west passage in a latitude low enough to be free from ice.