132 Wisconsin Academy of Sciences, Arts, and Letters. 



HOW DID THE ABOEIGINES OF THIS COUNTRY 

 FABRICATE COPPER IMPLEMENTS. 



BY P. R. HOY, M. D., President Wisconsin Academy of Sciences. 



I propose to consider the manner in wiiichthe 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 hlovm 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 

 mjury to the casting will be incurred from the impermeable na- 

 ture of the moulding material. In moulding an accurate pattern 



