The progress hitherto noted has related chiefly to the tools of the workman. In Mexico, and still more in Central America and Peru, those were applied both to sculpture and architecture on a grand scale. But some of the most singular memorials of the primitive architecture of the New World survive in the form of gigantic earthworks, perpetuating in their construction remarkable evidence of geometrical skill. Along the broad levels drained by the Mississippi and its numerous tributaries traces of America’s allophylian population abound; and the Ohio valley is pre-eminently remarkable for the number and magnitude of such works. The Ohio and its tributary streams flow through a fine undulating, fertile country, which now forms one of the great centres of population; and the evidence of modern enterprise and skill which abounds there gives additional interest to traces which disclose to us proof that this vast area is not now rescued for the first time from the primeval forest, with its wild fauna, and still wilder savage man. In a region such as this, attracting population to the broad alluvial terraces overlooking its smoothly-flowiug rivers, it was natural that the building instinct of man should first employ itself on earthworks; and that the monuments should assume a pyramidal form. The great mound of Miamisburg, Ohio, is sixty-eight feet high, and eight hundred and fifty-two feet in circumference at its base. The more famous Grave Creek Mound of Virginia rises to a height of seventy feet, and measures at its base one thousand feet in circumference. Other and still larger earthworks have been noted, such as the truncated pyramid at Cahokia, Illinois, which, while it remained intact, occupied an area upwards of two thousand feet in circumference, and reared its level summit, of several acres in extent, to a height of ninety feet. But this last belongs to a different class from the sepulchral mounds which appear to be unsurpassed by any known works of their kind. “We have seen mounds,” remarks Flint, an American topographer, with a just appreciation of the relation of these earthworks to the features of the surrounding landscape, “which would require the labour of a thousand men employed on our canals, with all their mechanical aids, and the improved implements of their labour, for months. We have more than once hesitated in view of one of those prodigious mounds, whether it were not really a natural hill. But they are uniformly so placed, in reference to the adjacent country, and their conformation is so unique and similar, that no eye hesitates long in referring them to the class of artificial erections.” The exploration of these huge earth pyramids has set at rest any doubts as to their artificial origin; and has, moreover, established the fact that they are structures erected to perpetuate the memory of the honoured dead in ages utterly forgotten, and by a race of which they preserve almost the sole remaining vestiges.