620 THE ICE AGE IN NORTH AMERICA. 



which they were fashioned, in a great many different localities^ 

 I think, therefore, I have gained an acquaintance with the 

 character of the fracture of very many different kinds of stone, 

 which have been broken by man intentionally for his use as tools. 

 I say this, because I have always been in the habit of compar- 

 ing and contrasting such broken stones with those whose fract- 

 ure had been occasioned by different natural forces, so that 

 I might learn the resemblances and the differences between 

 them. This is a subject which it is difficult to treat of satis- 

 factorily in writing, as it is so much an affair of ocular dem- 

 onstration. These little minute differences and peculiarities 

 are very palpable, when they are pointed out, although a geolo- 

 gist, or a mineralogist, who is perfectly familiar with the ma- 

 terial, but who may have had little or no training as an archae- 

 ologist, may have failed to notice them. The whole subject 

 is one solely for the judgment of the expert ; and when a 

 heap of broken stones, characterized by a general external re- 

 semblance, has been submitted to the determination of several 

 trained archaeologists, as I have often seen done in Europe, 

 there has been no difference of opinion among them as to 

 which were natural and which were artificial forms. Of course, 

 if the broken stones have been afterward subjected to the action 

 of running water, so as to produce a general wearing away of the 

 edges of the fractures, the difficulty of discriminating becomes 

 much greater. In such cases only a very practiced eye can de- 

 cide, and the opinion of any man, however eminent he may 

 be in other departments of knowledge, who has not had great 

 archaeological experience, is practically worthless. 



It was in the autumn of 1880 when we visited Trenton, 

 and at that time I found a few palaeoliths there myself ; after- 

 ward Di\ Abbott gave me quite a collection of his own find- 

 ing, which I have had ever since in my possession, and have 

 continually studied. So in repeated instances have I examined 

 his great collection in the Peabody Museum. At a meeting 

 of the Boston Society of Natural History, in January, 1881, 

 I expressed my conviction as to the artificial character of 

 these argillite implements, notwithstanding the fact that the. 

 coarseness of their material precludes their ever equaling in 

 workmanship the flint implements of Europe. My subsequent 



