Hearne continued his voyage down the Coppermine River with his bloodthirsty companions, until he reached the mouth on July 18th, 1771. He found that it was full of islets and shoals, with many seals on the ice outside. For 30 miles there had been nothing but barren hills and marshes. Above that distance there were stunted pines and dwarf willows on the river banks. In returning, he visited one of the surface copper mines. He gives an interesting account of the musk oxen, deer, wild geese, salmon, and other sources of food-supply, and of the building habits of beavers, and describes the Eskimo weapons and mode of life. [Illustration: Alexander Mackenzie] On June 29th, 1772, Hearne returned to Fort Prince of Wales, and was soon afterwards rewarded by being made Governor. But in 1782 a French Expedition under La Pérouse destroyed the fort, carrying off Hearne and the other Company’s servants as prisoners. Hearne was several years a prisoner of war, and only returned to London to die. This disaster so affected the faithful Matonabi that he committed suicide. It was 18 years after Hearne’s discovery of the mouth of the Coppermine that a young man named Alexander Mackenzie undertook to trace the course of another river, flowing north from the Great Slave Lake. This explorer was not one of the Hudson’s Bay Company’s servants, but at an early period of life he had been led, with commercial views, to the vast region north-west of Lake Superior. His voyage down the river which received his name was undertaken in six canoes, chiefly manned by French Canadians. Starting in June, 1789, he reached the numerous channels which form the estuary of the Mackenzie river on July 13th, and thus was the second European to reach the American polar ocean. The river journey was over 1000 miles in length. Mackenzie was knighted in recognition of the value of his discovery. It was in a year between the dates of the two river mouth discoveries that Captain Cook, during his third voyage, made his researches in the Arctic Sea between the two continents of Asia and America. The _Resolution_ under the command of the great navigator himself, and the _Discovery_ under Captain Clerke, were commissioned in 1776, but it was not until August, 1778, that they crossed the Arctic Circle. The first Lieutenant of the _Discovery_ was James Burney, so well known to geographers as the historian of voyages in the Pacific, and the writer of an interesting account of Cook’s Arctic discoveries.