160 Bibliographical Notices. 



the field. The mode of mcidcation of such facts varies too much 

 with books and teachers. The mere exercise of memory in learning a 

 table of classification is a poor substitute for the knowledge obtained 

 by the student from a good practical teacher. 



After a succinct notice of the history of the science, in which the 

 origin of inductive geology forms an interesting and instructive sec- 

 tion, the author enters upon elementary views of the structure and 

 composition of the crust of the earth and of the preservation and dis- 

 tribution of organic remains. 



To this succeeds a series of chapters descriptive of the primary, 

 hypozoic, palaeozoic, mesozoic, and cainozoic strata, in the ascending 

 order. In this respect we regard this plan of arrangement as pre- 

 ferable, inasmuch as it provides the student with the true suc- 

 cessional ordination of the various geognostical phsenomena. Thus 

 he is better enabled to trace the origin of the successive and deri- 

 vative strata, — the varying hydrographical areas more or less defined 

 by these deposits, — and tlie gradual advance, in different directions 

 and under varying circumstances, of vegetable and animal organisms ; 

 — and hence he is presented with a comprehensive view of the various 

 phases of the earth's physical history. 



Following the chapters on descriptive geology is a chapter devoted 

 to modern causes in action, — a section which we are inclined to think 

 should take its place at the commencement of the work ; for the 

 ordinary mind, when acquainted with existing physical agencies, not 

 only better appreciates the present operations of nature, but possesses 

 an index and a key to the multitude and apparent mystery of ancient 

 physical phaenomena. 



Inorganic phsenomena, more especially those connected with the 

 effects of heat, are fully treated of in the next following divisions of 

 the work ; — one chapter being devoted specially to the subject of 

 Mineral veins. 



In a subsequent chapter, on the state of geological theory, we 

 would particularly recommend to notice the section on geological 

 chronology, in which the probable rate of accumulation of deposits 

 is inferred from the study of the mechanical and chemical origin of 

 strata, — the alternations of beds of different lithological characters, 

 and of different natures, such as marine, freshwater, and igneous, — the 

 succession of races of imbedded organic beings, — and lastly, the repe- 

 titions of convulsions, and the metamorphism of rock-masses. In 

 the same chapter we find two useful tables illustrative of the distinct 

 groups of animal life which have followed one another in a settled 

 order of geological time. The one, adapted from M. A. d'Orbigny, 

 affords a rough estimate of the proportional number of species of all 

 animals in the several geological groups ; the second, repeated from 

 the author's work on Yorkshire, has reference to the distribution in 

 time of the more prominent vertebrate types specially characteristic 

 of the great geological periods. 



The appendix of tables and calculations contains also some prac- 

 tical observations on the instruments used by the working geologist, 

 namely, barometers, clinometers, &c., with directions for the benefit 



