MACKENZIE, SIR ALEXANDER, a well-known navigator, was a native of Scotland, and emigrated to Canada at an early age. After being engaged for some years at Fort Chipewyan in the north-west fur trade, he formed the project of reaching, by an overland route, the coast of the Northern Polar Ocean. Starting from Chipewyan on the 3d of June 1789, with a company, in four canoes, he sailed down the Slave River to its outlet in the Slave Lake. He then coasted along the lake, and reaching its western extremity, entered the river which afterwards received his name. Following the stream in its N.W. course, he issued forth into the Great Frozen Ocean on the 15th of July, and had thus achieved an important discovery. Mackenzie returned by the same route, and reached Chipewyan after an absence of more than a hundred days. A more arduous adventure was his overland journey to the North Pacific. He set out in October 1792, sailed for a considerable distance up Peace River, and after braving numerous hardships and dangers, reached his destination in July 1793. He followed the same track on his return. Mackenzie afterwards repaired to England, and published his Voyages through North America to the Frozen and Pacific Oceans in 1789 and 1793, 4to, London, 1801. In 1802 his successful enterprises were rewarded by the honour of knighthood. He died in 1820.