tained that the circular inclosures are perfect circles, and the square inclosures perfect squares. They were constructed with a geometrical precision which implies a kind of knowledge in the builders that may be called scientific. Figures 13, 14, 15, 16 show some of the more

Fig. 16.-Rectangular Work, Randolph County, Indiana.

important works of the Mound-Builders, chiefly in Ohio. Relics of art have been dug from some of the mounds, consisting of a considerable variety of ornaments and implements, made of copper, silver, obsidian, porphyry, and greenstone, finely wrought. There are axes, single and double; adzes, chisels, drills or gravers, lance-heads, knives, bracelets, pendants, beads, and the like, made of copper. There are articles of pottery, elegantly designed and finished; ornaments made of silver, bone, mica from the Alleghanies, and shells from the Gulf of Mexico.

The articles made of stone show fine workmanship; some of them are elaborately carved. Tools of some

very hard material must have been required to work the porphyry in this manner. Obsidian is a volcanic product largely used by the ancient Mexicans and Peruvians for arms and cutting instruments. It is found in its natural state nowhere nearer the Mississippi Valley than the Mexican mountains of Cerro Gordo.

There appears to be evidence that the Mound-Builders had the art of spinning and weaving, for cloth has been found among their remains. At the meeting of the International Congress of Pre-Historic Archæology held at Norwich, England, in 1868, one of the speakers stated this fact as follows: "Fragments of charred cloth made of spun fibres have been found in the mounds. A specimen of such cloth, taken from a mound in Butler County, Ohio, is in Blackmore Museum, Salisbury. In the same collection are several lumps of burnt clay which formed part of the 'altar,' so called, in a mound in Ross County, Ohio: to this clay a few charred threads are still attached." Figures 17

Mr. Schoolcraft gives this account of a discovery made in West Virginia: “Antique tube: telescopic device. In the course of excavations made in 1842 in the easternmost of the three mounds of the Elizabethtown group, several tubes of stone were disclosed, the precise object of which has been the subject of various opinions. The longest measured twelve inches, the shortest eight. Three of them were carved out of steatite, being skillfully cut and polished. The diameter of the tube externally was one inch and four tenths; the bore, eight tenths of an inch. This calibre was continued till within three eighths of an inch of the sight end, when it diminishes to two tenths of an inch. By placing the eye at the diminished end, the extraneous light is shut from the pupil, and distant objects are more clearly discerned."

He points out that the carving and workmanship generally are very superior to Indian pipe carvings, and adds, if this article was a work of the Mound-Builders "intended for a telescopic tube, it is a most interesting relic." An ancient Peruvian relic, found a few years since, shows the figure of a man wrought in silver, in the act of studying the heavens through such a tube. Similar tubes have been found among relics of the Mound-Builders in Ohio and elsewhere. In Mexico, Captain Dupaix saw sculptured on a peculiar stone structure the figure of a man making use of one. Astronomical devices were sculptured below the figure. This structure he supposed to have been used for observation of the stars. His account of it will be given in the chapter on Mexican and Central American ruins.

The Mound-Builders used large quantities of copper such as that taken from the copper beds on Lake Superior, where the extensive mines yield copper, not in the ore, but as pure metal. It exists in those beds in immense masses, in small veins, and in separated lumps of various sizes. The Mound-Builders worked this copper without smelting it. Spots of pure silver are frequently found studding the surface of Lake Superior copper, and appearing as if welded to it, but not alloyed with it. No other copper has this peculiarity; but copper with similar blotches of silver has been dug from the mounds. It was naturally inferred from this fact that the ancient people represented by these antiquities had some knowledge of the art of mining copper which had been used in the copper region of Lake Superior. This inference finally became an ascertained fact.

THEIR ANCIENT MINING WORKS.

Remains of their mining works were first discovered in 1848 by Mr. S. O. Knapp, agent of the Minnesota Mining Company, and in 1849 they were described by Dr. Charles T. Jackson, in his geological report to the national government. Those described were found at the Minnesota mine, in upper Michigan, near Lake Superior. Their mining was chiefly surface work; that is to say, they worked the surface of the veins in open pits and trenches. At the Minnesota mine, the greatest depth of their excavations was thirty feet; and here, "not far below the bottom of a trough-like cavity, among a mass of leaves, sticks, and water, Mr. Knapp discovered a de