JUNE 7, 1901.] 
determining efficiency. The discussion of ‘ tem- 
perature and fire’ is extended and good ; that 
of the problem of smoke prevention, the ac- 
count of the automatic stoker and the’ full 
elaboration of useful algebraic formulas are 
points of excellence deserving of special! men- ’ 
tion. The revelation of the effect of varying 
air-supply with variations of the rate of com- 
bustion is new and important as here presented, 
and the exposition of the value of flue-gas 
analysis is effected in an excellent fashion. 
For a first edition, this seems exceptionally 
free from typographical or other errors, and it 
may be taken for granted that later editions will 
follow from which even these minor defects wills 
be completely pruned. 
The book-making is good, and the maps are 
printed upon a fine grade of paper to insure 
clearness. Many of the illustrations and nearly 
all the diagrams are new, and the whole con- 
stitutes a work which is likely to have exten- 
sive sale among professionals and professional 
schools. The mathematical work and the dis- 
cussions of results of boiler-tests, of which the 
records are presented very fully, will find con- 
stant use. 
R. H. THURSTON. 
A Reader in Physical Geography. By RiIcHARD 
E. Doper. New York, Longmans Green & 
Co. 1900. 12mo. Pp.‘ viii+ 237. Price, 
70 cents. 
It is gratifying to see the new point of view 
in physical geography coming into our educa- 
tion and our literature. The application of the 
theory of evolution to all branches of the sub- 
ject has taken it bodily from the static’ condi- 
tion in which it was conceived by our fathers, 
and reestablished it as a dynamic? science, live 
and growing. There are no longer any ‘ ever- 
lasting hills,’ but mountains and vales wax and 
wane, and record the histories of their muta- 
tions in the landscape so legibly that he who 
runs may read. And man comes on the scene, 
molded inevitably by the geographic environ- 
ment in which his lot is cast, and in turn reacts 
upon that environment in many important 
ways. This is the outlook Professor Dodge 
has in his little volume. He has written it for 
beginners, and his fine quality as an instructor 
SCIENCE. — 
907 
is in evidence on almost every page. He is 
very happy in his ability to interpret the prin- 
ciples of land sculpture in the most homely 
similes. The beginner not only may, he must, 
relate the new knowledge to what is already 
‘well known to him. 
The topics treated are, The Continents, The 
Industries of Men, The Origin of Land Forms, 
The Great Land Forms, Climate and other im- 
portant physical features influencing man. 
The book is intended as auxiliary reading for 
beginners in physiography, but it will also’ 
make good reading for the laity in other lines, 
who wish to know the way in which a physiog- 
rapher looks at his problems. 
J. PAUL GOODE. 
Air, Water and Food. By ELLEN H. Ricwarps * 
and ALpHEuUS G. WoopmAN. New York, 
John Wiley & Sons. Pp. 230. Price $2.00. 
The first portion of the book covers the com- 
position and impurities of air and their relation 
to human life. The problem of ventilation is 
dwelt upon, and very proper reference is made 
to the faulty argument so often advanced that, 
because carbon dioxide is heavier than air, that 
therefore the proper method of securing its re- 
moyal from living rooms is to provide exits for 
it near the floor. The public forget that the 
gas, as the sanitarian meets it, is warm, not 
cold; and that, moreover, the principle of gas- 
eous diffusion has caused a more or less com- 
plete mixture of all the gases present in the 
room. 
Chapter IV. gives well stated methods for air 
analysis. 
Some eighty pages are given to the subject of 
water, its source, properties, relation to health 
and the methods employed for its examination. 
Following the directions for the ‘ determina- 
tion’ of each item in water analysis, there is 
found a paragraph entitled ‘ Notes,’ wherein are 
given in a very acceptable form the sundry 
hints and cautions so necessary for the guidance 
of the beginner. An excellent statement is 
found on page 81, to wit: ‘‘ The value ofa water 
analysis is in direct proportion to the knowledge 
and experience of the one who interprets it.”’ 
Again, on page 66, ‘‘ The conclusions are not 
infallible, but there are enough unavoidable 
