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Messrs. Editors.

HAVE read with much pleasure Professor Winchell's paper on the "Ancient Copper-Mines of Isle Royale," in "The Popular Science Monthly" for September. As the Professor's very laudable object is undoubtedly "to make a little history" respecting the wonderful copper-mines of Lake Superior, and as no narrative (with the exception of some occasional geological reports) respecting the late working of them has to my knowledge been published, and as he has inadvertently made some quite important omissions, with your leave I will endeavor to supply the deficiency. On page 602 he says: "The finding of these thin chips of copper is the first indication of the proximity of a large mass. In the summer of 1874 the first of these large masses was discovered."

In the summer of 1822, fifty-two years before "the summer of 1874," General Cass, at that time the United States Territorial Governor of what now constitutes the States of Michigan, Wisconsin, and Minnesota, and ex-officio Superintendent of Indian Affairs for the Northwest, made his celebrated trip from Detroit to the head of Lake Superior, with his party, "in birchen canoes," and thence overland to the Mississippi River. He stopped at the mouth of the Ontonagon River, on the south shore of Lake Superior, two or three days to recruit his voyageurs after a "canoe-paddle" of nearly one thousand miles from Detroit. Knowing what the "early Jesuits" had said about copper in that country, in the published memoirs of their operations in the "Great Lake country," nearly two hundred years before, he naturally sought information of the Indians he found there respecting it. They took him to a mass of copper which was lying on the bank of the Ontonagon River, some eight miles from its mouth. It was found to be, apparently, pure native copper. In 1845, I think it was, Julius Eldred, of Detroit, by permission of the Government, took it to Washington, for the purpose of its being eventually put into the Washington Monument, as a contribution showing the mineral resources of Michigan. It weighed something like six thousand pounds. In 1848 the Minnesota Mining Company commenced work on their mine, in the range of hills some twenty-one miles (by the course of the stream) up the Ontonagon River. They began work in what are called the "ancient diggings." This "digging" was simply an open trench, some ten to twelve feet wide, running on the course of a mineral vein that had been excavated by the "ancients" in the "country rock" to uncover the vein. I do not now recollect the length of that particular trench. The country is full of them.

I give you what Mr. William Hickok, one of the owners and originators of the Minnesota mine—which mine, by-the-way, has produced several million dollars' worth of copper—and who now resides at Tarrytown in this State, says of their work and what they found. In reply to a note I addressed him respecting it on the 25th ultimo, he writes: "The mass of copper discovered by Mr. Knapp in the Minnesota mine in 1848, of which you inquire, was found in the vein, resting upon skids about twenty-five feet from the surface. It weighed 12,480 pounds. All the rock had been cleaned from its surface, giving it the appearance of being as pure as refined copper. There were found in the excavation a large number of 'stone hammers,' weighing from one to forty pounds each, and encircled by a 'groove' cut undoubtedly for the purpose of receiving a hickory 'withe,' to be used as a handle. There were also several copper implements, such as chisels, etc., found, that showed, from the manner they had been used—the battered heads of the chisels, for instance—that the art of hardening and welding that metal (an art now lost) was known by those who had made them. There was at that time growing in that excavation (which was filled with alluvial soil) over the vein and the mass of copper a hemlock-tree, of about three hundred and seventy-five years' growth, judging from the number of its concentric rings. We must, I think, go back to the 'stone age' to find the workers of these copper-mines. The discovery of the mass of copper in the vein of the Minnesota mine entirely free from rock, ready to be moved, unlocks the mystery of those 'floating masses'—that seen by General Cass was one of them—found in various places on the surface, showing that they had all been mined and taken from the veins, and had been abandoned while being transported to the lake, for some cause to us unknown."

It occurs to me that, if the foregoing is added to Professor Winchell's very valuable paper, the account of those remarkable