JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. I, DECEMBER 4, 1911. No. 9. 



GEOPHYSICS. — Geophysical research. 1 Arthur L. Day. 



To write the history of the earth is a very different undertaking 

 from writing the history of a people. In the latter case, a dili- 

 gent seeker can usually find some ancient monastery where far- 

 sighted historians of an earlier generation have collected the more 

 important records which he requires, and placed them within 

 reach of his hand. With the earth's history, which is the prov- 

 ince of geology, it is another matter. The great globe has been 

 millions of years in the making, and except for a mere fragment 

 of its most recent history, it has had neither a historian nor an 

 observer. Its formation has not only extended over an almost 

 incomprehensible interval of time, but we have no parallel in our 

 limited experience to help us to understand its complicated devel- 

 opment, and no system of classification adequate to the task, 

 even of grouping in an orderly way all the observed rock and 

 mineral formations with reference to the forces which moulded 

 them. And even if we could correctly interpret all the visible 

 rock records, we are still quite helpless to comprehend all those 

 earlier activities of the formation period, whose record is now 

 obliterated. 



To the student of the earth's history, therefore, the problem 

 of gathering and ordering such a widely scattered and hetero- 

 geneous collection of effects and causes is one of somewhat over- 

 whelming scope and complication. In the industrial world, a 

 situation of this kind soon results in replacing individual effort 

 with collective effort, in the organization of a system of a scope 



i 



Presidential address delivered at the 700th meeting of t he Philosophical Society 

 of Washington, November 2.5, 1911. 



247 



