President's Address. 



319 



entombment, and are entitled to assign to them a still 

 higher antiquity. In fact, we know that all changes in 

 physical conditions, and all removals and extinctions of life, 

 take place by slow and silent stages, and that the greater 

 the difference between the existing and the extinct, the 

 longer must be the time that has elaped since their extinc- 

 tion. By methods such as these we can establish a scale of 

 old, older, oldest ; and there need be no more uncertainty 

 about the results obtained by such methods than there is 

 about the results obtained by the historian in modern, medi- 

 eval, and ancient history. 



Another method by which we arrive at notions of relative 

 antiquity is by the implements and works of art that occur 

 in recent formations, or accompany the remains of man. 

 We know the phases of modern, medieval, Eoman, Greek, 

 Egyptian, and Babylonian art, and can assign something 

 like a historical date to such objects and the accumulations 

 in which they occur. We know, too, that man employs 

 tools of wood and stone long before he learns the uses of the 

 metals ; and that he reduces the softer metals, and works in 

 copper and bronze, long before he has acquired the mastery 

 over iron and steel. In this way we speak of the ages of 

 stone, bronze, and iron, the one preceding the other, and 

 forming, as it were, a rude scale of time for the antiquarian 

 and geologist. But while one nation may be working in 

 iron, another more belated may be working in bronze, and 

 a third, still more remote and savage, may be adhering to 

 implements of wood and stone. To be of any use, this scale 

 of stone, bronze, and iron must be applied to the same dis- 

 trict ; and when so applied, archaeologists are now pretty 

 well agreed that it marks with considerable certainty the 

 various stages of relative antiquity. Of course, were imple- 

 ments of iron ever found along with remains of mammoth 

 and mastodon, the scale would be utterly worthless ; but 

 when stone tools invariably accompany the older remains, 

 and those of bronze and iron those of younger and younger 

 date, then we feel assured from this concordance of the im- 

 plement scale with that of the animal that we have hit upon 

 a pretty exact method, so far as Europe at least is con- 



