264 DISCUSSION OF THE DESICCATION QUESTION. 



It may here be permitted briefly to pass in review the various points 

 which have been taken np and discussed in the preceding pages. After a 

 somewhat detailed account of the phenomena of glaciation on the western 

 side of the North American continent, the facts indicatino- a diminution of 

 the precipitation and a general decrease of water surface in that region dur- 

 ing the later geological ages were stated. The same was then attempted 

 to be done for other regions, notably for Asia and the countries bordering on 

 the Mediterranean. The evidence of desiccation, begun certainly before the 

 Tertiai'Y epoch and continued into historic times, seems to the writer to be 

 so coirent that assent to its validity cannot be refused. 



That the proved desiccation was not, as is popularly supposed, the work of 

 man,. and due to the destruction of the forests, the author next endeavored 

 to demonstrate. It was farther attempted to be shown that the various facts 

 presented indicating decreased precipitation could not be accounted for by 

 simply considering them as a phase of a preceding epoch of glaciation. 



This led naturally to an examination of the conditions tending to favor or 

 diminish precipitation, in the course of which it was sliowu that an increase 

 of land surface on the globe and a diminution oi' the temperature would be 

 causes acting powerfull}^ to bring about the described phenomena of desic- 

 cation. Farther inquiry ns to whether geological investigations rendered the 

 existence of the first cause probable seemed to give an affirmative result. 

 The next step was to endeavor to ascei-tain whether there was proof of a 

 diminiition of temperature on the earth's surface. The records of instru- 

 mental observations were examined, and the result found to be uncertain, 

 owing to the very short time during which accurate observations had been 

 taken. Other facts, however, seemed to show, almost beyond possibility of 

 doubt, that there had been a marked decrease of the temperature in certain 

 regions during the historic period. The evidence of such diminution during 

 the geological period was found to be abundant and convincing. The cause 

 of such diminution was referred to the fact that the sun is a cooling body, in 

 accordance with the views of scientists of the highest eminence. 



It now remains to show that the ideas maintained in the pi-eceding pages 

 are not in conflict with the phenomena of the so-called "Glacial epoch;" and 

 to this our efforts will be directed in the succeeding chapter. 



