^56 KANSAS CITY REVIEW OF SCIENCE. 
Mound-builders had advanced at least as far as the ancient Egyptians in mathe- 
matical skill; any modern surveyor can appreciate what difficulty there would 
be in drawing a perfect circle which should enclose an area of ten or twenty 
acres. In some instances circles and squares enter into various combinations 
and these are repeated in separate localities with such exactness that there remains 
no doubt of their possessing a well-defined meaning if we could but discover it. 
Some of the most remarkable of these earthworks are in the vicinity of Cin- 
cinnati. 
III. Mines and excavations. Numerous traces have been left by the Mound- 
builders in the mining regions of Lake Superior. As an instance of their temer- 
ity in mining operations, it may be mentioned that, at one place, a piece of pure 
copper, weighi/ig over five tons, was fourid fifteen feet below the surface beneath 
trees at least four hundred years old. After having been elevated a distance of 
several feet from its original bed, by means of skids, the attempt to raise it seems 
to have been abandoned. The mass of mineral bore marks of fire, and stone 
tools were scattered about. So sagacious were these ancient miners in locating 
their mines that modern prospectors feel certain of a rich find whenever the traces 
of their work are discovered. In working these mines, sledge-hammers of stone 
were used weighing from thirty to forty pounds and wielded by means of a handle 
of twisted withes. Wooden shovels were also used; specimens having been pre- 
served by ^he antiseptic action of copper-salts.. While the Mound-builders seem 
to have been unacquainted with the value of the immense deposits of iron-ore 
within their reach, they were perhaps the only people who made use of iron, in 
any form, at the stage of progress reached by them. Iron pyrites was mined by 
them and worked up into mirrors and other ornaments. They also quarried ex- 
tensively to procure various kinds of rock as materials from which to fashion 
their pipes, weapons and utensils. At Golden Grove, in Barton County, Mis- 
souri, th6re are remains of ancient excavations, which have always been a riddle 
to the inhabitants. It is thought by some that they are remains of De Soto's 
gold-hunting expeditions ; and in that belief no insignificant sum has been sunk 
in attempting to find treasure. All of the shafts opened were stopped by a strata. 
of hard porphyritic rock, which, in my opinion, was the real object sought by 
those who made the excavations — the Mound-builders. This view is strength- 
ened by the fact that porphyry has been found in mounds removed hundreds of 
miles from localities where this rock is found. The mound-builders also mined 
galena, though not to any considerable extent. It is but seldom found in the 
mounds. In North Carolina are ancient quarries from whence they drew the 
mica which formed so important an element in their funeral offerings throughout 
the Mississippi Valley. 
IV. Arts and manufactures. It is hardly necessary to enter into a minute 
description of the specimens of arms, utensils and ornaments exhumed from the 
mounds. They have been familiar to all residents of the Mississippi Valley since 
childhood. At any rate, I shall pass over all such common and well-known 
relics as arrow-heads, stone knives, hatchets and hammers, and in fact, all ob- 
