i 9 o THE POPULAR SCIENCE MONTHLY. 



They are most abundant where the agricultural capabilities of 

 the country are greatest, and we find them associated with areas 

 of special fertility in such a way as to prove that they had 

 stripped the forest from these areas, and chiefly derived their 

 subsistence from their cultivation. Hence we learn that they 

 were a sedentary and agricultural people. Yet their structures 

 are for the most part earthworks walls for defense, or to form 

 inelosures, sepulchral mounds, etc. ; and while we find what seem 

 to be raised foundations of extensive buildings, those buildings 

 have disappeared, and we must hence conclude that they were for 

 the most part structures of wood. 



The mound-builders were ignorant of the use of iron, and prob- 

 ably possessed no other metals than copper, which they mined 

 extensively, but never smelted ; for we find their implements com- 

 posed of the native metal, often with specks of silver, thus betray- 

 ing its source on Lake Superior, and only hammered into shape. 

 From this copper they made battle-axes, daggers, knives, awls, 

 and ornaments; but most of their tools and weapons were of 

 stone, and many of them were laboriously and tastefully wrought. 



They have left no evidence that they had a knowledge of 

 masonry an art in which the inhabitants of the table-lands so 

 much excelled. 



This is the more remarkable, as stone easily quarried abounds 

 in the vicinity of their works, and some of the great structures of 

 our Western table-lands, whose builders apparently had not the 

 use of metals, show what good work could be done without me- 

 tallic tools. 



I have said that the mound-builders made use of but a single 

 metal copper and yet they were industrious and enterprising 

 miners. Their copper mines on Lake Superior have been often 

 and fully described. They must have been worked for genera- 

 tions, since the ancient excavations exceed in magnitude all the 

 work of the white man in that region ; but the methods which 

 they used were exceedingly rude and simple. 



They had no knowledge of metallurgy, and the Lake Superior 

 copper was only available for their purpose because it occurs in 

 the metallic state. They excavated the rock by the use of fire, 

 stone hammers, and wooden shovels. 



They never penetrated the earth to a greater depth than sixty 

 to eighty feet, and for ladders they used the trunks of trees from 

 which the branches projected at frequent intervals, and these were 

 cut off to form steps. Since no considerable structures belonging 

 to this people have been found near the Lake Superior mines, it 

 seems probable that their mining operations were carried on only 

 in summer, and by parties who, migrating from the lower country 

 in the spring, returned in autumn. 



