1897] SOME NEW BOOKS 421 



hoped that his work will lead to the more detailed study of the 

 changes produced in rocks as they weather down and pass into their 

 final, but by no means least useful, form. The illustrations are for the 

 most part clear and well chosen, but it would be well to indicate the 

 exact magnification of the diagrams oi' microscopic objects in the text. 



Tht. Volcanoes of North America 



Volcanoes of Nobth America : A Reading Lesson for Students of Geography 



AND Gkoliicy. P>y Israel C. Russell, Professor of Geology, University of Michigan. 

 Svo. Pp. xiv + 346, with 1(5 plates and 11 figs, in text. New York: The 

 Macmillan Co. ; London : Macmillan & Co., Ltd. 1897. Price, 16s. net. 



The second title of this handsomely printed book must be regarded as 

 that which expresses the intentions of its author. To the American 

 reader, the work is an introduction to the study of volcanoes, com- 

 parable to those of Prof. Judd and others, which are already 

 familiar to us in Europe. Only 170 pages, or half the book, deal with 

 the volcanoes of North America ; and it is to these that the professed 

 geologist will most naturally turn. Considered, then, in its dual 

 aspect, Prof. Russell's work must do much to stimulate curiosity 

 and observation in the United States, by pointing out the absorbing 

 interest of volcanic phenomena, and the extraordinary illustrations of 

 the subject possessed by the North American continent. 



Vesuvius, as seems inevitable, introduces the description of com- 

 plex volcanic mountains ; and the famous photographs of 1872 

 repeat themselves on the second plate. Nor will the beginner feel 

 any irritation at perusing the graphic details provided by the 

 younger Pliny. He is directed to Mr Lobley's book on Vesuvius for 

 a history of the mountain ; and w T e should have liked a reference also 

 to the classic work of Phillips. Palmieri's experiences, and the report 

 of the Krakatoa committee, are then drawn on ; and these passages 

 conclude with a remarkable quotation, from " one of our most pro- 

 found students of volcanic phenomena " (p. 28), to the effect that 

 the performances of Vesuvius " are mere Fourth of July fireworks 

 in comparison with the Day of Judgment proceedings of Krakatoa." 

 Prof. Russell's own good taste and style fortunately prevent his 

 imitating this profundity, even where, as in Chapter VIII., he allows 

 himself romantic possibilities. 



Dutton and Dana furnish the account of Hawaii, and the Deccan 

 trap and the Newark system of the Atlantic coast are quoted as 

 examples of surface-flows of vast extent. In the latter instance, 

 we may remind ourselves of the wide field of literature and ' solid 

 geology ' already traversed by Prof. Eussell in the Eastern States. 



The terms ' aa ' and ' pahoehoe ' seem to have gained vitality in 

 geological literature (pp. 60-62), just as we might borrow with profit 

 many of the names by which a Highlander or a Welshman designates 

 the various forms of mountains. Prof. Eussell refers the ' aa ' type 

 of lava-surface to imperfectly fluid streams, in opposition to what has 

 been stated to occur upon the slopes of Vesuvius. The pahoehoe, 

 on the contrary, flows easily and cools in thin sheets before it 

 can break up, furnishing a smooth and often glassy surface. 



The classification and description of igneous rocks professes only 



