One of the best evidences which we have of the systematic government and habits of the Mound-builders, together with the comparatively advanced state of the practical arts among them, is found in the ancient copper mines of the Lake Superior Region so extensively operated by them at quite a remote period.[71] These were first discovered by Mr. S. O. Knapp, agent of the Minnesota Mining Company, in 1848. One excavation explored by this gentleman was thirty feet deep, filled with clay and a mass of mouldering vegetable matter. Eighteen feet from the surface he found a mass of copper ten feet long, three feet wide and two feet thick, weighing over six tons. By digging around this great lump of metal, he observed that it was resting on “a cob-work of round logs or skids six or eight inches in diameter, the ends of which showed plainly the strokes of a small axe or cutting tool about two and a half inches in width”. The wood, from its exposure to moisture, had lost all its consistency, and opposed no more resistance to a knife-blade than would ordinary peat. After having raised the mass of copper over five feet along the foot wall of the lode on the timbers by means of wedges, the ancient miners had abandoned the task. The walls of the mine still show the marks of fire; charcoal and stone mauls were taken from this and similar excavations. The largest of these mauls weighed thirty-six pounds and was encircled by a double groove around its centre. Withes were probably wound in these grooves by which two men could wield the maul very effectively. The number of smaller hammers of greenstone and porphyry removed from these works by Mr. Knapp exceeded ten cart-loads. In one of the pits a rude oak ladder was found, made by trimming the branches of a tree at a distance from the trunk to leave a sufficient foothold. Wooden levers, preserved beneath the water, were also of frequent occurrence. A copper maul, shaped by pounding in a cold state, and weighing upwards of twenty pounds, was found in this locality, as well as many well-formed copper implements designed for various purposes. Upon a mound of rubbish near one of the excavations, Messrs. Foster and Whitney saw a pine stump ten feet in circumference—the trunk having been broken fifteen feet from the ground—which must have grown and died after the earth was thrown up. Mr. Knapp mentions a hemlock which he found growing on a heap of rubbish which had 395 rings of annual growth. Fallen and decayed trees of a previous generation were found lying across the pits. In front of the Waterbury mine are blocks of stone weighing two and three tons which had been removed by the ancient miners from the shaft, and when observed by Colonel Whittlesey, they were covered by a forest growth of the full size and kind common to the neighboring region. Under a pile of rubbish the remains of a trough of cedar bark was brought to light and had been used to carry off water baled from the mine by means of