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THE POPULAR SCIENCE MONTHLY 



rudimentary books for introducing begin- 

 ners to the subject and for use in ordinary 

 schools. But a good college text-book of 

 geology has hitherto been wanting. There 

 has been no American work for high-class 

 institutions which treats the subject so as 

 to meet the requirements of intelligent and 

 scholarly people, who yet do not expect to 

 become independent cultivators of geologi- 

 cal science. This manifest gap has now 

 been filled by the publication of the work 

 before us, and a careful examination of the 

 volume convinces us that it has been ex- 

 ecuted with great judgment with reference 

 to the present needs of higher education. 

 In his preface Prof. Le Conte thus states 

 the purpose he had in view in writing the 

 work : " I have attempted to realize what 

 I conceive to be comprised in the word 

 elements as contradistinguished from man- 

 ual. I have attempted to give a really sci- 

 entific presentation of all the departments 

 of the wide field of geology, at the same 

 time avoiding too great multiplication of 

 detail. I have desired to make a work 

 which shall be both interesting and profit- 

 able to the intelligent general reader, and 

 at the same time a suitable text-book for 

 the higher classes of our colleges. In the 

 selection of material and mode of presenta- 

 tion, I have been guided by long experience 

 as to what it is possible to make interesting 

 to a class of young men, somewhat advanced 

 in general culture and eager for knowledge, 

 but not expecting to become special geolo- 

 gists. In a word, I have tried to give such 

 knowledge as every thoroughly cultured 

 man ought to have, and at the same time is 

 a suitable foundation for the further pros- 

 ecution of the subject to those who so 

 desire. The work is the substance of a 

 course of lectures to a senior class, organ- 

 ized, compacted, and disencumbered of too 

 much detail by representation for many suc- 

 cessive years, and now for the first time 

 reduced to writing." 



But, besides preparing a comprehensive 

 text-book, suited to present demands, which 

 was the author's main design, he has also 

 given us a volume of great value as an ex- 

 position of the subject, thoroughly up to 

 date. It is well known that geology is one 

 of the most rapidly progressive of the sci- 

 ences, but in recent years its advances have 



been very remarkable. Not only are its 

 facts multiplying at an unprecedented rate, 

 through the labors of the increasing multi- 

 tude of geological observers in all lands, but 

 its progress is to a still greater degree sig- 

 nalized by the light thrown upon it by vari- 

 ous other sciences, and by the working out 

 of fundamental principles by which its mul- 

 titudinous details are organized into more 

 perfect method. The law of evolution is 

 now the key to geology. A vague principle 

 of progress has long been obscurely recog- 

 nized in geological phenomena, but that 

 principle has now been brought out, ampli- 

 fied, formulated, and established, as the all- 

 interpreting law that has governed the un- 

 folding of the globe. Much remains to be 

 done, no doubt, in the elucidation of this 

 grand principle, but its imperfection now 

 becomes a measure of the imperfection of 

 geology itself, and no presentation of that 

 science is any longer possible which does 

 not give prominence to the doctrine of evo- 

 lution. Prof. Le Conte not only accepts it, 

 but puts it to its proper scientific use, as 

 his volume bears abundant witness, and as 

 he explains in the following words from the 

 preface: "In the historical part, I have 

 found much more difficulty in being scien- 

 tific without being tiresome, and in being 

 interesting without being superficial and 

 wordy. I have attempted to accomplish 

 this difficult task by making evolution the 

 central idea about which many of the facts 

 are grouped. I have tried to keep this idea 

 in view, as a thread running through the 

 whole history, sometimes very slender 

 sometimes, indeed, invisible ; but reappear- 

 ing from time to time to give consistency 

 and meaning to the history." 



The examples and applications of Prof. 

 Le Conte's work are almost entirely derived 

 from this country, so that the treatise may 

 be properly considered an American geol- 

 ogy. This involves no narrowness or in- 

 completeness ; for, although science is as 

 wide as Nature, yet the illustrations of geol- 

 ogy are necessarily local, and an important 

 point is gained when those are selected 

 which will be most naturally observed by 

 the great mass of students for whom the 

 volume was designed. The region of the 

 Rocky Mountains and the Western portions 

 of the continent, as is well known, have 



