Wooden frame-works and skids have been found, which were made with sharp-edged instruments, but upon being exposed to the air have turned to dust. It is thought that the area covered by the ancient works in the Lake Superior region is more extensive than that which includes the modern mines, but that the forests have overgrown and conceal from view the excavations. Of course a considerable period elapsed after the Welsh occupied the Ohio valley before they and those with whom they became incorporated penetrated so far northward to work these mines. Most of the relics which have been discovered in the mounds were, in all probability, made from the metals of that region. Colonel Whittlesey, who is an authority on this subject, thinks that the miners "went up from the settlements farther south in the summers, remained in the copper regions through the season, and worked the mines in organized companies until the advance of winter terminated their operations. As they were more advanced in civilization than the aborigines, they probably had better means of transportation than bark canoes." In the enthusiasm of antiquarian research, many have been led to assign too great an age to the earthen defences and mounds of our country. The Cardiff Giant was pronounced, with scholarly awe, to be a fine specimen of an extinct race which trod this earth thousands of years before Adam drew breath, but was subsequently discovered to have been made from a chunk of gypsum taken from a quarry in Iowa. The remains of Fort Necessity, erected to cover the retreat of Braddock's defeated army, now wear such an antiquarian aspect that if there were no historical data respecting them they would be classed with the mounds. So with Forts Hamilton and Meigs, on the Miami and Maumee Rivers, and others, constructed only about one hundred years ago. When native forest trees are cleared away and the soil is turned over for the purpose of embankments, a new growth of vegetation is quickly started. Some years ago, a large oak was cut down in Lyons, New York, and on its being sawed there were found near the centre the marks of an axe. On counting the concentric circles, it was discovered that four hundred and sixty had been formed since the cutting was made. The block was brought to Newark and exhibited in a hotel there. All who saw it declared that the work had been done with an _edged_ tool. The trees covering the mounds in Wyoming, as described by Chapman, had annular rings numbering from six to seven hundred. President Harrison observed that it would take the trees, growing where a forest was cut down fifty years since, five hundred years to equal in height the surrounding woods; and that a forest of the largest trees at the mouth of the Great Miami, consisting of fifteen acres, covers the ruins left by former races.