48 00SM03. 



the equatorial aids exceeds the polar axis of the globe, and 

 Bhows T/s the mean equality of the flattening of the two hemi- 

 spheres, without entailing on us the necessity of giving the 

 detail of the measurement of the degrees in the meridian, or 

 the observations on the pendulum, which have led us to know 

 that the true figure of our globe is not exactly that of a regu- 

 lar ellipsoid of revolution, and that this irregularity is reflect- 

 ed in the corresponding irregularity of the movements of the 

 moon. 



The views of comparative geography have been specially 

 enlarged by that admirable work, Erdkunde im Verhdltniss 

 zur Natur und zur Geschichte, in which Carl Ritter so ably 

 delineates the physiognomy of our globe, and shows the influ- 

 ence of its external configuration on the physical phenomena 

 on its surface, on the migrations, laws, and manners of nations, 

 and on all the principal historical events enacted upon the face 

 of the earth. 



France possesses an immortal work, L' Exposition du Sys- 

 teme du Monde, in which the author has combined the results 

 of the highest astronomical and mathematical labors, and pre- 

 sented them to his readers free from all processes of demon- 

 stration. The structure of the heavens is here reduced to the 

 simple solution of a great problem in mechanics ; yet Laplace's 

 work has never yet been accused of incompleteness and want 

 of profundity. 



The distinction between dissimilar subjects, and the sepa- 

 raition of the general from the special, are not only conducive 

 to the attainment of perspicuity in the composition of a phys- 

 i'.al history of the universe, but are also the means by which 

 a, character of greater elevation may be imparted to the study 

 of nature. By the suppression of all unnecessary detail, the 

 great masses are better seen, and the reasoning faculty is ena- 

 bled to grasp all that might otherwise escape the limited range 

 of the senses. 



The exposition of general results has, it must be owned, been 

 singularly facilitated by the happy revolution experienced since 

 t he close of the last century, in the condition of all the special 

 i-ciences, more particularly of geology, chemistry, and descrip- 

 'ive natural history. In proportion as laws admit of more 

 .general application, and as sciences mutually enrich each other, 

 ind by their extension become connected together in more nu- 

 merous and more intimate relations, the development of gen- 

 eral truths may be given with conciseness devoid of superfici- 

 ality. On being first examined, all phenomena appear to ba 



