Mr. Knapp, the agent of the Minnesota Mining Company, was the first to point out these pre-historic mines. In 1847, his researches having led him into a cavern much frequented by porcupines, he discovered, under an accumulation of heaped-up earth, a vein of native copper, containing a great number of stone hammers. A short time afterwards, some other excavations 25 to 35 feet in depth, and stretching over an extent of several miles, came under his notice. The earth dug out had been thrown on each side of the excavations; and mighty forest-trees had taken root and grown there. In the trunk of a hemlock-tree growing in this "made ground," Mr. Knapp counted 395 rings of growth, and this tree had probably been preceded by other forest-giants no less venerable. In the trenches themselves, which had been gradually filled up by vegetable débris, trees had formerly grown which, after having lived for hundreds of years, had succumbed and decayed; being then replaced by other generations of vegetation, the duration of which had been quite as long. When, therefore, we consider these workings of the native copper-mines of Lake Superior, we are compelled to ascribe the above-named excavations to a considerable antiquity.

In many of these ancient diggings stone hammers have been found, sometimes in large quantities. One of the diggings contained some great diorite hatchets which were worked by the aid of a handle, and also large cylindrical masses of the same substance hollowed out to receive a handle. These sledges, which are too heavy to be lifted by one man alone, were doubtless used for breaking off lumps of copper, and then reducing them to fragments of a size which could easily be carried away. If we may put faith in Professor Mather, who explored these ancient mines, some of the rocks still bore the mark of the blow they had received from these granite rollers.

The work employed in adapting the native copper was of the most simple character. The Indians hammered it cold, and, taking into account its malleable character, they were enabled with tolerable facility to give it any shape that they wished.

In America, just as in Europe, a great number of specimens of pre-historic pottery have been collected. They are, it must be confessed, superior to most of those found in the ancient world. The material of which they were made is very fine, excepting in the case of the vessels of every-day use, in which the clay is mixed with quartz reduced to powder; the shapes of the vessels are of the purest character, and the utmost care has been devoted to the workmanship. They do not appear to have been constructed by the aid of the potter's wheel; but Messrs. Squier and Davis, very competent American archæologists, are of opinion that the Indians, in doing this kind of work, made use of a stick held in the middle. The workman turned this stick round and round inside the mass of clay, which an assistant kept on adding to all round the circumference.

In regard to pottery, the most interesting specimens are the pipes, which we should, indeed, expect to meet with in the native country of the tobacco plant and the classic calumet. Many of these pipes are carved in the shape of animals, which are very faithfully represented. These figures are very various in character, including quadrupeds and birds of all kinds. Indeed, in the state of Ohio seven pipes were found on each of which the manatee was so plainly depicted that it is impossible to mistake the sculptor's intention. This discovery is a curious one, from the fact that at the present day the manatee is not met with except in localities 300 or 400 leagues distant, as in Florida.

The pre-historic ornaments and trinkets found in North America consist of bracelets, necklaces, earrings, &c. The bracelets are copper rings bent by hammering, so that the two ends meet. The necklaces are composed of shell beads (of which considerable quantities have been collected) shells, animals' teeth, and small flakes of mica, all perforated by a hole so as to be strung on a thread. The earrings also are made of the same material.

All these objects—weapons, implements, pottery, and ornaments—have been derived from certain gigantic works which exhibit some similarity, and occasionally even a striking resemblance, to the great earthwork constructions of the Old World. American archæologists have arranged these works in various classes according to the probable purpose for which they were intended; we shall now dwell for a short time on these divisions.

In the first place, we have the sepulchral mounds or tumuli, the numbers of which may be reckoned by tens of thousands. They vary in height from 6 feet to 80 feet, and are generally of a circular form; being found either separately or in groups. Most frequently only one skeleton is found in them, either reduced almost to ashes, or—which is more rare—in its ordinary condition, and in a crouching posture. By the side of the corpse are deposited trinkets, and, in a few cases, weapons. A practice the very contrary to this now obtains in America; and from this we may conclude that a profound modification of their ideas has taken place among the Indians since the pre-historic epochs.

It is now almost a certain fact that some of the small tumuli are nothing but the remains of mud-huts, especially as they do not contain either ashes or bones. Others, on the contrary, and some of the largest, contain a quantity of bones; the latter must be allied with the ossuaries or bone-pits, some of which contain the remains of several thousand individuals.