1 28 The American Geologist. f ebruafy, 1893 
in land forms were seen but they were described as isolated and fixed 
facts. Until geologists had shown that the earth's surface is not a 
finished product but is only one of a long series of conditions pro- 
duced by the action of continuous forces, acting in cycles; that it is 
the expression of the action of force on matter just as much as is the 
form of any organism, the descriptions had to be arbitrary and irra- 
tional. 
The recognition of this relation, however, makes the earth's surface 
the product of evolution. The idea of development through living 
processes binds the facts together into a unified whole. The subject 
becomes the study of the life of the earth. 
The systematic result of long and continuously acting processes 
dees not end with the mere evolution of the land surface. The con- 
dition of man. vA his industries, commerce, comforts, in a word, his 
civilization, is as much the result of the land he lives en and the air 
he lives in, as these are the result of the earth's vital forces. Physical 
geography thus becomes a study in evolution. 
Such a unifying idea pervades the book before us. Those who are 
accustomed to lock for the result of thorough digestion and careful 
analysis in a work from Prof. Davis' pen will not be disappointed 
in this. At every step it shows careful consideration. It is the ma- 
tured fruit of years of class-rcom work in the subject. Tlie crder of 
discussion is logical: the space given to the different divisions of the 
subject is fully in acocrd with their importance, and the relation of 
man to the many features described is carefully considered and fully 
brought out in both te.xt and illustrations. That part of the book in 
which land form is discussed is a clear statement of the principles of 
the evolution of land form, illustrated by full references to, and careful 
descriptions of, actual forms selected from many parts of the world. 
The first chapter deals with a few of the more striking cases in 
which man is profoundly influenced by his surroundings. Chapter II 
considers the earth as a globe. It is concerned chiefly with the size 
and shape of the earth and the usual heavenward excursion by the 
imagination is wisely omitted. 
The atmosphere is discussed in the space of 40 pages in the next 
chapter. The treatment is mainly descriptive and no knowledge of 
physics is presupposed. After describing the distribution of atmos- 
pheric temperature and pressures, atmospheric dynamics is discussed 
under the heads of the ideal planetary circulation, and terrestrial circu- 
lation: then cyclonic disturbances and their consequences follow, under 
several sub-headings. 
The ocean is next considered in a chapter of 30 pages. The main 
features of distribution, depth, temperature, composition and char- 
acter of bottom are briefly described. The consideration of the tides 
is brief and descriptive. 
The rest of the book is devoted to the discussion of the forms of 
the land. One short chapter deals with general considerations, such 
as changes, area and hight of the land, continental outline, varieties 
of rock, wasting of the land and life on the land. This chapter, within 
