Salisbury's Physiography 
139 
The part played by the atmosphere in the evolution of 
surface forms has received a treatment comparable in detail 
to that presented by special text-books of meteorology. The 
energy derived from the sun is followed through a series of 
transformations, in the chapters on atmospheric pressure, the 
movement of air currents, and the transportation of water 
vapor to its final precipitation upon the earth. The various 
elements of climate and the zones of climate receive due 
attention. In these chapters the composition of the atmos- 
phere, the air in its life relations, the distribution of temper- 
atures over the earth, and the philosophy of the movements of 
the air are treated in an interesting and original manner. 
The chapter on the storms of the United States is especially 
detailed and illustrated by a complete series of isothermal 
charts and weather maps. Following the chapters on the 
atmosphere, six chapters covering fifty pages are given to 
the discussion of the principal facts of oceanography. 
The book contains more than seven hundred illustrations, 
forty-three of which are sections of topographic maps; and of 
the others more than half are half-tones from excellent photo- 
graphs. This can by no means replace field-work but serves 
rather to invite to work out of doors; for the author says in 
his preface: “Another phase of work which should not be 
i 1 neglected is work out of doors. This must form a part of the 
work of every strong course in this subject. Directions for 
local field-work cannot be outlined profitably in a text-book, 
for the work must be shaped with reference to the specific 
locality where the subject is studied. Both field-work and 
map work should have for their aim the application of the 
principles studied, in such a way as to make the subject vital. 
The aim of every laboratory exercise carried out in connec- 
tion with this subject should be the same, and any laboratory 
work which does not either illustrate and enforce principles, 
or lead to them, is not worth development. The student 
who cannot apply what he has learned in the class-room to 
to his out-of-door surroundings, has not secured the maximum 
good from his study of the subject.” 
