Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume IV (1876-1877)
Hoy, P. R.
How did the Aborigines of this country fabricate copper implements, pp. 132-137 PDF (1.9 MB)
132 Wisconsin Academy of Sciences, Arts, and Letters. HOW DID THE ABORIGINES OF THIS COUNTRY FABRICATE COPPER IMPLEMENTS. BY P. R. HOY, M. D., President Wisconsin Academy of Sciences. I propose to consider the manner in which the ancient inhabitants of this country fabricated those curious copper implements which the plow and spade turn up all over Wisconsin and the adjacent states. These copper tools are objects of great interest to the archaeologist, and it is a matter of pride that the Wisconsin His- torical Society has the largest and best collection to be found in any state. A few of the specimens, upon a superficial examination, seem to be cast. This point will first be considered: Did these pre- historic people possess the skill and intelligence requisite to cast articles of pure copper ? Before a cast can be made, it is necessary, to have an exact copy moulded, either in sand, plaster, clay, metal, or other suitable substance. The formation of sand moulds is by no means so simple an affair as it seems at first thought. It requires long practical experience to overcome the disadvantages attendant upon the -materials used. The moulds must be sufficiently strong to withstand the action of the fluid metal perfectly, and at the same time to permit the egress of the gases formed by the action of the metal on the sand. If the material is air-tight, then danger would come from pressure, arising from the rapidity of the generating of the gases, and the casting would -be spoiled, and probably the operator injured. If the gases are locked up within the mould, the general result is what moulders term blown casting, that is, the surface becomes filled with bubbles of air. The preparation of sand and loam used in forming the mould must be carefully con- sidered. The greater the quantity of sand the more easily will the gases escape and the less liability is there of fracture of the casting. On the other hand, if the loam predominate, the im- pression of the pattern will be better, but a far greater liability of injury to the casting will be incurred from the impermeable na- ture of the moulding material. In moulding an accurate pattern
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