The mining operations of upwards of a quarter of a century have done much to efface the traces of the ancient works, as every indication of them is eagerly followed up by the modern miner, as the most promising clew to rich metalliferous deposits. But towards the close of 1874 Mr. Davis, an experienced old miner of Lake Superior, recovered from another ancient trench, in the same region, a solid mass of nearly pure copper, heart-shaped, and weighing between two and three tons. It lay at a depth of seventeen feet from the surface, as when originally detached from its bed by the ancient miners. Alongside of it were a number of smaller pieces, from a single ounce to seventeen pounds in weight, evidently broken off the large mass by the original workers of the mine. Numerous stone mauls and hammers also, weighing from ten to thirty pounds, lay scattered through the lower débris with which the trench was refilled. But the absence of any copper tools seemed to point to the final desertion of the mine, from some unknown cause, at the very time when its resources were most available. Attention was first directed to such traces of ancient mining operations, by the agent of the Minnesota Mining Company in 1847. Following up the indications of a continuous depression in the soil, he came at length to a cavern where he found several porcupines had fixed their quarters for hybernation; but detecting evidences of artificial excavation, he proceeded to clear out the accumulated soil, and not only exposed to view a vein of copper, but found in the rubbish numerous stone mauls and hammers of the ancient workmen. Subsequent observation brought to light excavations of great extent, frequently from twenty-five to thirty feet deep, and scattered over an area of several miles. The rubbish taken from these is piled up in mounds alongside; while the trenches have been gradually refilled with soil and decaying vegetable matter gathered through the long centuries since their desertion; and over all, the giants of the forest have grown, withered, and fallen to decay. Mr. Knapp, the agent of the Minnesota Company, counted 395 annular rings on a hemlock-tree, which grew on one of the mounds of earth thrown out of an ancient mine. Mr. Foster also notes the great size and age of a pine-stump which must have grown and died since the works were deserted; and Mr. Whittlesey not only refers to living trees upwards of three hundred years old, now flourishing in the abandoned trenches; but he adds: “on the same spot there are the decayed trunks of a preceding generation or generations of trees that have arrived at maturity and fallen down from old age.” The deserted mines are found at numerous points extending over upwards of a hundred miles along the southern shore of the lake; and reappear beyond it, in extensive excavations on Isle Royale. Sir William Logan reports others observed by him on the summit of a ridge at Maimanse, on the north