In the next five days Mackenzie's canoes successfully descended the river to the Great Slave Lake, a distance of some two hundred and thirty-five miles. The journey was not without its dangers. The Slave river has a varied course: at times it broadens out into a great sheet of water six miles across, flowing with a gentle current and carrying the light canoes gently upon its unruffled surface. In other places it is confined into a narrow channel, breaks into swift eddies and pours in boiling rapids over the jagged rocks. Over the upper rapids of the river, Mackenzie and his men were able to run their canoes fully laden; but lower down were long and arduous portages, rendered dangerous by the masses of broken ice still clinging to the banks of the river. As they neared the Great Slave Lake boisterous gales from the north-east lashed the surface of the river into foam and brought violent showers of rain. But the voyageurs were trained men, accustomed to face the dangers of northern navig

A week of travel brought them on June 9 to the Great Slave Lake. It was still early in the season. The rigour of winter was not yet relaxed. As far as the eye could see the surface of the lake presented an unbroken sheet of ice. Only along the shore had narrow lanes of open water appeared. The weather was bitterly cold, and there was no immediate prospect of the break-up of the ice.

For a fortnight Mackenzie and his party remained at the lake, skirting its shores as best they could, and searching among the bays and islands of its western end for the outlet towards the north which they knew must exist. Heavy rain, alternating with bitter cold, caused them much hardship. At times it froze so hard that a thin sheet of new ice covered even the open water of the lake. But as the month advanced the mass of old ice began slowly to break; strong winds drove it towards the north, and the canoes were presently able to pass, with great danger and difficulty, among the broken floes. Mackenzie met a band of Yellow Knife Indians, who assured him that a great river ran out of the west end of the lake, and offered a guide to aid him in finding the channel among the islands and sandbars of the lake. Convinced that his search would be successful, Mackenzie took all the remaining supplies into his canoes and sent back Leroux to Chipewyan with the news that he had gone north down the

But even after obtaining his guide Mackenzie