University of Wisconsin Digital Collections
Link to University of Wisconsin Digital Collections
Link to University of Wisconsin Digital Collections
The State of Wisconsin Collection

Page View

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)

Page 132

132    Wisconsin Academy of Sciences, Arts, and Letters.
        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

Go up to Top of Page