96 The Ohio Journal of Science [Vol. XVII, No. 3. 



not make a layer more than about a half mile thick. Thus some 

 other source of chlorine than wasting igneous rocks must be 

 found. 



Whatever fundamental theory ultimately is established for 

 the genesis of the earth, it will be reached by a long series of 

 approximations. A body of facts must be built up, and over 

 against it, a body of hypotheses. The research student must 

 work between the two bodies. A new fact or group of facts may 

 show the theory faulty in some particular, and make necessary 

 its revision. The revision of the theory will point to a possible 

 new field for investigation and the geologist will go in the quest 

 of new truth. This truth, when found, may go beyond the 

 theory again and thus require another revision. And so the 

 growth of the theoretic side will proceed parallel with the 

 growth of disclosed truth. A hypothesis for the origin of the 

 earth must be in harmony with all known and discoverable 

 facts of petrogenesis, paleontology, stratigraphy, and paleo- 

 geography ; must be supported by all facts known of seismology, 

 diastrophism, vulcanism, and ore deposition; and must take into 

 account all truth discovered by astronomer, physicist, chemist 

 and biologist. The geologist cannot complete his theoretic work 

 until the field work is done in his own and the several related 

 sciences. 



This emphasizes the need of earnest co-operation between all 

 scientists. "No man liveth unto himself." Men of all the 

 enumerated branches of science are asking for the geologist's 

 results. They, like geologists, cannot complete their tasks 

 until facts are drawn from many related fields. 



In conclusion, then, the geologist has in his own field many 

 times more to do than he has yet accomplished along almost all 

 lines; and he is not able to finish until other scientists have 

 finished, because his truth is so interwoven with theirs. Science 

 is one with many clo.sely related ramifications. But back of all 

 these items marshalled in previous paragraphs, items which 

 probably amply answer the question of my subject, are the two 

 incontrovertible facts that man is finite, while truth is infinite, 

 and hence the whole truth will never be known. Men are at 

 present making approximations toward it. We shall continue 

 so to do. Our children and children's children, for many 

 generations may also continue to do so, and with no fear of 

 exhausting their task. 



Oberlin College. 



