One important inference deducible from the peculiar features of the works here referred to, is the state of knowledge of their constructors. The most skilful engineer of our own day would find it difficult, without the aid of instruments, to lay down an accurate square on the scale of some of those described, enclosing an area four-fifths of a mile in circumference. Circles of moderate dimensions might indeed be constructed, so long as it was possible to describe them by a radius; but with such works measuring five thousand four hundred feet, or upwards of a mile in circumference, the ancient geometrician must have had instruments, and means of measuring arcs: for it seems impossible to conceive of the accurate construction of figures on such a scale, otherwise than by finding the angle by its arc, from station to station, through the whole course of their delineation. It is no less obvious from the correspondence in area and relative proportions of so many of the regular enclosures, that the Mound-Builders possessed a recognised standard of measurement; and that some peculiar significance, possibly of astronomical origin, was attached to figures of certain forms and dimensions.
Fig. 71.—Cincinnati Tablet.
The city of Cincinnati occupies a remarkable site, within a fine basin of hills, on the Ohio river, which had for its older occupants the remarkable people now referred to. But the growth of the modern city has swept away every vestige of their old earthworks; and no definite record of their details has been preserved. One memorial, however, survives, which was discovered in 1841, when excavating a large mound within the limits of the city. It has been the subject of ingenious speculations; and may have some bearing on our present investigations. In the centre of the mound, slightly below the level of the natural surface, a skeleton was found greatly decayed, alongside of which lay two pointed bones, about seven inches long, formed from the tibia of the elk, and the engraved tablet shown in the accompanying illustration (Fig. 71). It is made of fine-grained sandstone, and measures five inches in length, by two and six-tenths across the middle, and three inches at the ends. Upon its smooth surface an elaborate figure is represented, by sinking the interspaces within a rectangular border, so as to produce what has been regarded by some as a hieroglyphic inscription. But the most remarkable feature of its graven device is the series of lines by which the plain surface at each end is divided. The ends of the stone, it will be observed, form arcs of circles of different dimensions. The greater arc is divided by a series of lines, twenty-seven in number, into equal spaces, and within this is another series of seven oblique lines. The lesser arc at the opposite end is divided in like manner by two series of twenty-five and eight lines, similarly arranged. This tablet has not failed to receive due attention. It has been noted that it bears a “singular resemblance to the Egyptian cartouche.” Its series of lines were discovered to yield, in the sum of the products of the longer and shorter ones, a near approximation to the number of days of the year. An astronomical origin was accordingly assigned to it; and it has been surmised to be an ancient calendar, recording the approximation of the Mound-Builders to the true length of the solar year. Mr. Squier perhaps runs to an opposite extreme in suggesting that it is nothing more than a stamp, of which specimens have been found made of clay, both in Mexico and in the Mississippi mounds; and which were probably used in impressing ornamental patterns on cloth or prepared skins. Such clay stamps always betray their purpose by the handle attached to them, as in the corresponding bronze stamps common on Roman sites; whereas the Cincinnati tablet is about half an inch in thickness, with no means of holding or using it as a stamp, and bears on its unfinished reverse grooves apparently made in sharpening the tools by which it was engraved. But whatever theory be adopted as to its original object or destination, the series of lines on its two ends have justly attracted attention: for they constitute no part of the device; and can scarcely be regarded as an ornamental border. Possibly in them we have a record of certain scales of measurement in use by the Mound-Builders; and if so, the discovery is calculated to add fresh interest to our study of the geometrical structures, which, far more than their great mounds, are the true characteristics of that mysterious people.[[86]]
The precise objects aimed at in the construction of the remarkable series of American earthworks here referred to must obviously be difficult to determine with certainty. Analogies to these structures have been traced in the works of Indian tribes formerly in occupation of Carolina and Georgia. They were accustomed to erect a circular terrace or platform on which their council-house stood. In front of this, a quadrangular area was enclosed with earthen embankments, within which public games were played and captives tortured. To this was sometimes added a square or quadrangular terrace at the opposite end of the enclosure. Upon the circular platform it is also affirmed that the sacred fire was maintained by the Creek Indians, as part of their most cherished rites as worshippers of the sun. But even the evidence, thus far, is vague and unsatisfactory; and any recognisable analogies point, at best, only to the possibility of some of the Indian tribes having perpetuated on a greatly inferior scale some maimed rites borrowed from their civilised precursors. The scale upon which the Southern Indian earthworks were constructed may compare with those of the Iroquois in the State of New York, but in no degree approximates to the erections of the Mound-Builders. What, for example, shall we make of the graded ways, such as that of Piketon, Ohio, where an approach has been laboriously formed from one terrace to another, one thousand and eighty feet long by two hundred and fifteen feet in greatest width? The excavated earth has been employed, in part, to construct lofty embankments on each side of the ascent, which are now covered with trees of large size. Beyond this approach, mounds and half-obliterated earthworks indicate that it was only part of an extensive series of structures. But, viewed alone, it is one of the most remarkable monuments of prehistoric times to be found on the whole continent, and certainly bears not the slightest resemblance, either in its character or the great scale on which it is executed, to any known work of the Red Indians.
| [83] | Ancient Monuments of the Mississippi Valley, pp. 26-29, plate x. |
| [84] | Ancient Monuments of the Mississippi Valley, p. 48. |
| [85] | Ancient Monuments of the Mississippi Valley, p. 57. |
| [86] | The woodcut is engraved from a rubbing taken from the original. Mr. Whittlesey has included this tablet among his “Archæological Frauds”; but the result of inquiries made by me during a recent visit to Cincinnati has removed from my mind any doubt of its genuineness. |