474 Review, 



tance which the earth deviates from the tangent of its orbit ; which 

 tangent the earth would follow, in virtue of its inertia, did not 

 some cause draw it towards the solar centre ?" 



Of this brilliant and novel conjecture, the learned editor of Le 

 Cosmos, from whom we extract the above, remarks, that it seems 

 to be one of those happy inspirations which belong to truth alone ; 

 and he adds, " there is great merit in having originated an idea 

 which has never before presented itself to the human intelligence 

 and which, in time to come, may bring forth fruitful results." — Le 

 Cosmos, Nov. 21, 1862. t. s. h. 



REVIEW. 



DANA'S MANUAL OF GEOLOGY.* 



In no part of the world has the science of geology been more 

 successfully cultivated than in North America. But the results 

 that have been arrived at, are scattered through a multitude of 

 reports of the different surveys, and papers of greater or less 

 length in the scientific journals. Up to the present time he who 

 has endeavored to get a clear idea of the geology of the whole 

 North American continent has found it necessary to devote more 

 time and means to the object, than most students can well afford. 

 In the important work, just issued by Professor Dana, this great 

 difficulty is removed. We have now in one compact and beauti- 

 fully illustrated book, not only a comprehensive and well-balanced 

 account of the elementary principles of the science, but also the 

 general results of what has been ascertained of the geology of 

 this continent, down to the present moment. We have not, just 

 now, leisure to give a full review of this excellent publication, and 

 must therefore content ourselves with a mere glance at its contents. 

 Prof. Dana has divided his subject into four parts, as follows. — 



1. Physiographic Geology. — In this part of the work, are 

 described the forms of the earth's surface, as exhibited in the 



* Manual of Geology : treating of the principles of the science with 

 special reference to American Geological History, for the use of Col- 

 leges, Academies, and Schools of Science. By James D. Dana, M. A., 

 LL. D., Silliman Professor of Geology and Natural History in Yale 

 College, &c., &c. Hlustratedby a chart of the world, and over one 

 thousand figures, mostly from American sources. Philadelphia: pub- 

 lished by Theodore Bliss & Co. London: Triibner & Co. 1863. Small 

 8vo, pp. 812. 



