NEED OF MEASUREMENTS 223 



a period too narrow for their requirements, I can see 

 no reason on the geological side why they should not 

 be at liberty to enlarge it as far as they may find to be 

 needful for the evolution of organised existence on the 

 globe. As I have already remarked, it is not the length 

 of time which interests us so much as the determination 

 of the relative chronology of the events which were 

 transacted within that time. As to the general suc- 

 cession of these events, there can be no dispute. We 

 have traced its stages from the bottom of the oldest 

 rocks up to the surface of the present continents and 

 the floor of the present seas. We know that these 

 stages have followed each other in orderly advance, 

 and that geological time, whatever limits may be 

 assigned to it, has sufficed for the passage of the long 

 stately procession. 



We may, therefore, well leave the dispute about the 

 age of the earth to the decision of the future. In so 

 doing, however, I should be glad if we could carry away 

 from it something of greater service to science than the 

 consciousness of having striven our best in a barren 

 controversy, wherein concession has all to be on one 

 side and the selection of arguments entirely on the 

 other. During these years of prolonged debate I have 

 often been painfully conscious that in this subject, as in 

 so many others throughout the geological domain, the 

 want of accurate numerical data is a serious hindrance to 

 the progress of our science. Heartily do I acknow- 

 ledge that much has been done in the way of measure- 

 ment and experiment for the purpose of providing a 

 foundation for estimates and deductions. But infinitely 

 more remains to be accomplished. The field of investi- 



