A quantity of pottery, many implements of copper, and a large number of spear-heads chipped out of quartz and manganese garnet, were also deposited on the hearth; but they were intermixed with much coal and ashes, and were all more or less melted or broken up with the intense action of the fire. Out of a bushel or two of fragments of the spear-heads, and of from fifty to a hundred quartz arrow-heads, only four specimens were recovered entire. Scattered over the deposits of earth filling one of the compartments, were traces of a number of pieces of timber, four or five feet long, supposed by the explorers to have supported a funeral or sacrificial pile. They had been somewhat burned, and the carbonised surface preserved their casts in the hard earth, although the wood had entirely decayed. They had been heaped over while glowing, for the earth around them was slightly baked; and thus, after repeated, and perhaps long-protracted sacrificial rites, some grand final service had consummated the religious mysteries; and the blazing altar was quenched by means of the tumulus that was to preserve it for the instruction of future ages. The evidence that some of the altars remained in use for a considerable period, and were repeatedly renewed ere they were finally covered over, has suggested the idea that they are no more than the hearths of the ancient Mound-Builders’ dwellings. But in some cases a single altar-hearth has been found within extensive circumvallations. When in groups their enclosures are slight demarcations, as of places sacred to religious observances, and not defensive embankments with outer ditch. Their contents cannot be regarded as mere miscellaneous deposits, either like the waste heap of an Indian hut, or the contents of the modern Indian’s ossuary; and it is obvious that those hearths have been systematically overlaid with mounds constructed with great care, even where they were devoid of other traces than the ashes of their final fires. In one large mound, for example, one hundred and forty feet in length, by sixty feet in greatest breadth,—already referred to as that in which so many quartz spear and arrow-heads, with copper and other relics, were found;—a new and smaller hearth was observed to have been constructed within the oblong basin of the original altar. In this all the relics deposited in the mound were placed, and the outer compartments of the large basin had been filled up with earth to a uniform level, the surface of which showed traces of fire. A more minute examination led to the discovery that three successive altars had been constructed, one above another, in addition to the smaller hearth or focus which had received the final offerings, ere it was buried under its enclosing mound. In other examples the altars have been observed to be very slightly burned; but wherever such was the case, they have also been destitute of remains.