80 The American Naturalist. [January, 
sia, Thursby’s, Gunn’s Grove and Cook’s Ferry). But many others 
again (Mount Royal, etc., etc.), which showed, from top to bottom, no 
trace of the white man, must, inferably, have been built before the com- 
ing of Europeans. 
(d) MOUND COPPER NOT OF EUROPEAN ORIGIN. 
To find an object of European make in a mound, is to date the 
mound after white contact, that is certain. But when we ask which 
objects were and which were not of European make or snggestion, and 
set aside a number of things easily in one category or the other, we 
soon come to the doubtful case of copper—copper which was mined by 
the Indians on Lake Superior to be pounded cold into trinkets; cop- 
per which the Spaniards found Indians casting in moulds in Mexico, 
and which, on the other hand, was traded to Indians by Europeans in 
the sixteenth century, to be again worked into trinkets. The copper 
in these mounds (Tick Island and Mount Royal), as in Ohio, (Hope- 
well’s) appears in such smooth and extremely thin discs and plates, 
that, spite of its position at the mound’s base, with no associated trace 
of Europe; spite of the aboriginal pattern, certain archaeologists 
would not believe itof American manufacture. Until Mr. F. H. Cush- 
ing succeeded in reproducing the specimens in cold hammered native cop- 
per, with Indian tools, the opinion held its own that the mound-makers 
had cut the shapes out of machine-rolled sheets brought from Europe. 
To settle this question, Mr. Moore has employed, at great pains and 
with great credit to his energy, the test of analysis. 
That a component alloy should occur in European copper of the 
time in question, which never occurs in these mound specimens, and 
which likewise never occurs in the pure native material found in 
America, was a lucky chance. But such was proved, in a reasonable 
number of analyses, to be the case, and it settled the question. The 
tell-tale alloy is lead. The mound copper examined always had fewer 
impurities (sometimes only,silver and iron) than the European, anti- 
mony and arsenic were from 19 to 45 times less abundant in mound 
copper than in European, but lead was always present in the Euro- 
pean and never in the mound specimens analyzed. 
It was only making assurance doubly sure to urge, after this, that. 
the mound designs were aboriginal; that the objects of the same kind 
differed in size and shape, which, inferably, machine-made specimens 
would not do; that the Mount Royal breast-plate, though symmetri- 
_ eal, was not mechanically so; that the large plates were not originally 
made from single sheets, such as European mechanics would have fur- 
