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 of microscopic objects in the text. 
THE VOLCANOES OF NortTH AMERICA 
VoucAnors oF Nortu AmrericA: A RrapING LESSON FOR STUDENTS OF GEOGRAPHY 
AND GroLocy. By Israel C. Russell, Professor of Geology, University of Michigan. 
8vo. Pp. xiv+346, with 16 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 voleanoes 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 voleanic phenomena, and the extraordinary illustrations of 
the subject possessed by the North American continent. 
Vesuvius, as seems inevitable, introduces the description of com- 
plex voleanic mountains; and the famous photographs of 1872 
repeat themselves on the second plate. Nor will the beginner feel 
any iritation 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 we 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 voleanic 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 imstance, 
we may remind ourselves of the wide field of literature and ‘solid 
geology’ already traversed by Prof. Russell 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. Russell 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 
