INTRODUCTION. 49 



JK. *Jed, and it is only by the result of a multiplicity of obser- 

 vations, combined by reason, that we are able to trace the 

 mutual relations existing between them. If, however, in the 

 present age, which is so strongly characterized by a brilliant 

 course of scientific discoveries, we perceive a want of connec- 

 tion in the phenomena of certain sciences, we may anticipate 

 the revelation of new facts, whose importance will probably 

 be commensurate with the attention directed to these branches 

 of study. Expectations of this nature may be entertained with 

 regard to meteorology, several parts of optics, and to radiating 

 heat, and electro-magnetism, since the admirable discoveries 

 of Melloni and Faraday. A fertile field is here opened to dis- 

 covery, although the voltaic pile has already taught us the 

 intimate connection existing between electric, magnetic, and 

 chemical phenomena. Who will venture to affirm that we 

 have any precise knowledge, in the present day, of that part 

 of the atmosphere which is not oxygen, or that thousands of 

 gaseous substances affecting our organs may not be mixed with 

 the nitrogen, or, finally, that we have even discovered the whole 

 number of the forces which pervade the universe ? 



It is not the purpose of this essay on the physical history of 

 the world to reduce all sensible phenomena to a small number 

 of abstract principles, based on reason only. The physical 

 history of the universe, whose exposition I attempt to develop, 

 does not pretend to rise to the perilous abstractions of a purely 

 rational science of nature, and is simply a physical geography, 

 combined with a description of tlie regions of space and the 

 bodies occupying tlicm. Devoid of the profoundness of a purely 

 speculative philosophy, my essay on the Cosmos treats of the 

 contemplation of the universe, and is based upon a rational 

 empiricism, that is to say, upon the results of the facts regis- 

 tered by science, and tested by the operations of the intellect. 

 It is within these limits alone that the work, which I now 

 venture to undertake, appertains to the sphere of labor to 

 which I have devoted myself throughout the course of my 

 long scientific career. The path of inquiry is not unknown 

 to me, although it may be pursued by others with greater 

 success. The unity which I seek to attain in the development 

 of the great phenomena of the universe is analogous to that 

 which historical composition is capable of acquiring. All 

 points relating to the accidental individualities, and tl e essen- 

 tial variations of the actual, whether in the form and arrange- 

 ment of natural objects in the struggle of man against the 

 elements, or of nations against nations, do not admit of being 



VOL. I C 



