224 SEE— FURTHER RESEARCHES ON [April 24, 



monizing in any considerable degree the divergent views heretofore 

 prevailing, and of showing that there is no important geological- 

 phenomenon tvhich the new theory does not explain in a more simpte 

 and direct manner than the old theory, such a comparison will no 

 doubt seem quite justifiable. For it is highly desirable to establish 

 the adequacy of the new theory to explain the geological as well as 

 the physical phenomena noticed at the surface of the earth. 



In making this comparison it is necessary to bear in mind that 

 the geological data on many points are still very incomplete, and 

 therefore we should expect agreement with the body of phenomena 

 rather than with the details, about which much uncertainty still 

 exists. Owing to the incompleteness of our knowledge of the mode 

 of origin of the great mountain chains of the globe, the best plan 

 of procedure seems to be : First, to give an exposition of the views 

 of previous writers in regard to the individual great mountain sys- 

 tems; second, to add a resume of the views of certain great geolo- 

 gists on mountain formation in general. Obviously such conden- 

 sation of the views of others should wherever possible be given in 

 their own words. 



As this subject is extensive and widely scattered in a variety 

 of publications, we must content ourselves with selecting those 

 citations which seem of most interest, without in any way claiming 

 to exhaust the subject. Indeed it may well be that some discussions 

 of value will be entirely overlooked, but, as the theories have been 

 but very little changed for many years, it is hoped that the following 

 citations will be found adequate to give an intelligent grasp of the 

 views heretofore accepted by the leading authorities. If there be 

 those who doubt the propriety of including lengthy quotations 

 from well-known authors, I must plead in extension of the course 

 here adopted, that this memoir is intended for others besides geolo- 

 gists, and that all who are interested in the physics of the earth, 

 whether they be mathematicians, astronomers, physicists, seismolo- 

 gists, geologists, or even chemists and biologists, are entitled to have 

 a clear summary of the principal theories heretofore accepted in re- 

 gard to the development of our globe. In dealing with a subject of 

 such universal interest to all men of science, any reasonable conden- 

 sation of the previous theories may be considered admissible, and one 



