evidence not only of great and protracted labour, but also of the use of other tools than those of stone. Accumulated vegetable matter had refilled the excavations to a level with the surrounding surface, and over this the forest extended with the same luxuriance as on the natural soil. In this barren and rocky region the filling up of the trenches with vegetable soil must have been the work of many centuries; so that the whole aspect of the deserted mines of Isle Royale confirms the antiquity ascribed to them. What appear to the eye of the traveller as the giants of the primeval forest, are the growth of comparatively modern centuries, subsequent to the era when the shores of Lake Superior rang with the echoes of industrial toil. Two or three centuries would seem altogether inadequate to furnish the requisite time for the most partial accumulation of soil and decayed vegetable matter with which the old miners’ trenches have been filled. Four centuries thereafter are indisputably recorded by recent survivors of the forest, independent of all traces of previous arborescent generations; and thus in the excavations and tools of the copper regions of Lake Superior, we look on memorials of a metallurgic industry long prior to those closing years of the fifteenth century, in which the mineral wealth of the New World awoke the Spanish lust for gold. An uncertain, yet considerable interval must be assumed between the abandonment of those ancient works, and the forest’s earliest growth; and thus we are thrown back, at latest, into centuries corresponding to Europe’s mediæval era for a period to which to assign those singularly interesting traces of a lost American civilisation. Owing to the filling up of the abandoned mining trenches with water, not only the copper and stone implements of the miners are found, but examples of wooden tools and timber framing have also been preserved, in several cases in wonderful perfection; and these furnish interesting supplementary evidence of the character of their industrial arts. [Illustration: FIG. 63.—Miners’ Shovels.]