250 REPORT OF NATIONAL MUSEUM, 1892. 



acquainted with the character and value of the work done by their 

 colleagues. 



The differences of opinion which have been referred to have neces- 

 sarily produced corresponding differences in practice among" geologists, 

 and 1 have therefore found it necessary to consider them in connection 

 with the application of the principles discussed in these essays to the 

 practical work of the geologist. In doing so I have taken occasion to 

 show that both extremes have had the effect not only to retard the 

 progress of geological science, but to diminish the practical value of 

 geological investigation. Furthermore, I have taken every oppor- 

 tunity to insist that notwithstanding the paramount value of fossil 

 remains in structural and systematic geology the geologist, when in- 

 vestigating these subjects will be without excuse if he should fail to 

 avail himself of every attainable relevant fact, whether biological or 

 physical. 



Finally, 1 have undertaken to point out some of the legitimate claims 

 which geological science may make, not only upon individual investi- 

 gators, but upon museums, and scientific organizations, and to show 

 that these claims are based upon the necessities of science and not upon 

 a sentimental idea. 



