Febeuaby 8, 1907] 



SCIENCE 



223 



Genesis, that the lights in the firmament of 

 heaven were to be for signs. 



It is altogether probable that entomologists, 

 before entering upon the course here marked 

 out for them, will demand a better statement 

 of guiding principles, and a better disposi- 

 tion of the ontogenetic and phylogenetic dif- 

 ficulties that beset the way. 



James G. Needham 



Minerals and How They Occur. By W. G. 

 Miller, Provincial Geologist of Ontario, 

 formerly Professor of Geology, School of 

 Mining, Queen's University. Toronto : The 

 Copp, Clark Company. 1906. 

 In his intention of producing a book on 

 mineralogy for ' secondary schools and pros- 

 pectors ' the author has succeeded admirably 

 both because of the clearness and simplicity 

 of his style and because of his accuracy of 

 statement. There is room for books of this 

 sort since, though the subject is of wide gen- 

 eral interest, there are few sources of informa- 

 tion which are attractive to the heginner. 

 The average book offered to the beginner is 

 not only inaccurate but lacks successful 

 arrangement and shows poverty of facts and 

 illustrations. Professor Miller's book con- 

 tains about two hundred illustrations and 

 these give such an idea of the subject as 

 descriptions could not convey. They are new, 

 well selected, and some of them are especially 

 good (e. g.. Figs. 20, 4Y, 63, Y9). 



The large amount of information contained 

 in the book is in attractive form. Upon look- 

 ing at the table of contents one might be re- 

 minded of Voltaire's essay on dogs in which 

 towards the close he says ' Speaking of dogs 

 reminds me of cats ' and proceeds to write a 

 short dissertation on cats. One might think 

 that the paragraphs on fossils were hardly 

 called for a book on mineralogy. But as he 

 becomes acquainted with the author's aim he 

 sees that the book differs from the ordinary 

 one which presents the science in its narrower 

 aspects and that it has been written just as 

 if the author were talking to interested be- 

 ginners before whom he must needs start with 

 the most obvious things — rocks, the common 

 rocks with which his readers are familiar — and 



build upon them his edifice. Such work 

 necessitates excursions into the surrounding 

 country and the result is a building all of 

 whose parts contribute to mineralogy. 



The more involved parts of the subject are 

 omitted or touched upon but lightly and the 

 things which are apt to prove most attractive 

 to beginners are presented in logical and com- 

 pact manner. 



A few changes might be suggested. 

 Though crystallography is the least palatable 

 side of the subject it is so essential as to 

 require more attention. When the axes of the 

 six systems are being given (Fig. 23) one 

 should not be omitted; the orientation should 

 be according to the almost universal method — 

 i. e., a should always be the axis pointing to 

 the observer, should always represent the short 

 axis in the orthorhombic and triclinic systems, 

 and the inclined axis in the monoclinic sys- 

 tem, p should represent the acute angle made 

 by the intersection of c and a and a by the 

 intersection of c and I. All of the simple 

 holohedral forms should be pictured and with 

 the axes drawn in them. Whether combina- 

 tion, twinned and hemihedral forms are pre- 

 sented may well depend on the space at the 

 disposal of the author. But if crystallography 

 is to be mentioned at all the first principles 

 should be given with clearness. 



An occasional statement like -the following 

 should be modified. "During late years this 

 theory of origin (of petroleum and natural 

 gas) has been questioned by many workers 

 who are inclined to believe that both materials 

 are of inorganic origin " (p. 59) . Forty years 

 ago Berthelot suggested that petroleum might 

 have originated from union of carbonated 

 waters with uncombined sodium and potas- 

 sium and about ten years after that Mendeleef 

 propounded as a possible origin the union of 

 such waters with metallic carbides. Thus the 

 theory can hardly he called a recent one and 

 in addition it appears to be a theory which 

 shows possibilities rather than the facts which 

 the study of oil fields the world over seems to 

 establish. The actual geological conditions in 

 oil fields necessitate the conclusion that oil 

 and natural gas are of organic origin. 



The book is full of valuable information 



