The time had now come, after the union of the North-West Company and the X Y Company, for pushing ahead the great work in their hands and examining the vast country across the Rocky Mountains. The United Company in 1805 naturally took up what had been planned several years before, and sent David Thompson up the Saskatchewan to explore the Columbia River and examine the vast "sea of mountains" bordering on the Pacific Ocean. The other partner chosen was Simon Fraser, and his orders were to go up the Peace River, cross the Rockies, and explore the region from its northern side. We shall see how well Fraser did his part, and meanwhile we may follow Thompson in his journey. In 1806, we find that he crossed the Rockies and built in the following year a trading-house for the North-West Company on the Lower Columbia. Thompson called his trading post Kootenay House, and indeed his persistent use of the term "Kootenay" rather than "Columbia," which he well knew was the name of the river, is somewhat remarkable. Coming over the pass during the summer he returned to Kootenay House and wintered there in 1807-1808. During the summer of 1808, he visited possibly Grand Portage, certainly Fort Vermilion. Fort Vermilion, a short distance above the present Fort Pitt, was well down the north branch of the Saskatchewan River, and on his way to it, Thompson would pass Fort Augustus, a short distance below where Edmonton now stands, as well as Fort George. He left Fort Vermilion in September, and by October 21st, the Saskatchewan being frozen over, he laid up canoes for the winter, and taking horses, crossed the Rocky Mountains, took to canoes on the Columbia River again, and on November 10th arrived at his fort of Kootenay House, where he wintered. On this journey, Thompson discovered Howse's Pass, which is about 52 deg. N. latitude. In 1809, Thompson determined on extending his explorations southward on the Columbia River. A short distance south of the international boundary line, he built a post in September of that year. He seems to have spent the winter of this year in trying new routes, some of which he found impracticable, and can hardly be said to have wintered at any particular spot. In his pilgrimage, he went up the Kootenay River, which he called McGillivray's River, in honour of the famous partner, but the name has not been retained. Hastening to his post of Kootenay House, he rested a day, and travelling by means of canoes and horses, in great speed came eastward and reached Fort Augustus, eight days out from Kootenay, June 22nd, 1810. From this point he went eastward, at least as far as Rainy Lake, leaving his "little family" with his sister-in-law, a Cree woman, at Winnipeg River House.