At eight o'clock in the evening we came to Cranberry River and encamped, having, by their estimation, come twenty-three miles. The evening was perfectly clear and calm, with a striking twilight, which was remarked all night. These lengthened twilights form a very observable feature as we proceed north. Mackenzie says that, in lat. 67° 47´, on the 11th of July, 1789, he saw the sun above the horizon at twelve o'clock P.M. The calmness and beauty of the night, and our chief's anxiety to press forward, made this a short night. Gen. Cass aroused the camp at a very early hour, so that at three o'clock we were again upon the lake, urging our way up the Fond du Lac Bay. The sun rose above the horizon at ten minutes before four o'clock. The morning was clear and brilliant. Not a cloud obscured the sky, and the waves of the lake spread out with the brightness of a mirror. At the distance of five leagues, we passed the mouth of the Wisakoda, or Broule River,[61] a stream which forms the connecting link with the Mississippi River, through the St. Croix. Three miles beyond this point we landed a short time, on the shore, where we observed a stratum of iron sand, pure and black, a foot in thickness. [61] WISACODA, or BROULE RIVER.--On returning down the Mississippi River, from the exploration of its sources, in 1832, I ascended the River St. Croix quite to its source in St. Croix Lake. A short portage, across a sandy summit, terminated at the head springs of the Wisacoda, which, from a very narrow and tortuous channel, is soon increased in volume by tributaries, and becomes a copious stream. Thus swelled in volume, it is dashed down an inclined plane, for nearly seventy miles, over which it roars and foams with the impetuosity of a torrent. It is not till within a few miles of Lake Superior that it becomes still and deep. The entire length of the river may be estimated at one hundred miles. It has two hundred and forty distinct rapids, at some of which the river sinks its level from eight to ten feet. It cannot fall, in this distance, less than 500. That it should ever have been used in the fur trade, is to be explained by the fact that it has much water. At eleven o'clock, a northeast wind arose, which enabled the expedition to hoist sail. Land on the north shore had for some time been in sight, across the bay, and the line of coast soon closed in front, denoting that we had reached the head of the lake. At twelve o'clock, we entered the month of the River St. Louis, having been eighteen days in passing this lake, including the trip to the Ontonagon.