: REVIEWS. - 
An appendix gives a great number of problems awaiting solution. These 
cover chiefly engineering (especially electrical) , physical, and chemical investi- 
gations, and many have been suggested by well-known leaders in research, The 
work is written in a refreshing non-technical style, and should be read by every 
thoughtful reader. Net price $2, our copy from Messrs. Angus and Robertson Ltd. 
The Theory and Practice of Aeroplane Design.—By S..T. G. Andrews, B.Sc., 
and 8. F. Benson, B.Se., London, Chapman & Hall, 1920 (pp. xii. + 454). 15s. '6d. 
This book is published as one of the Directly-Useful Technical Series which is 
intended to oceupy a midway position between. theoretical books written primarily 
for the training of students and practical books which omit the scientific basis 
upon which all good practice is built. The need of a reliable text-book on the 
theory and practice of aeroplane design has long been recognised by all those 
connected with aeronautical affairs. The present volume aims to supply this 
want, and will be found useful by designers, aeronautical draughtsmen, and 
students, hesides containing much of interest to the general reader. 
The study of aecronauties can only be successfully attempted by those possess- 
ing a good knowledge of mathematics and physics. Aeroplanes are machines 
containing many differing elements. These elements demand a great or less 
amount of scientific knowledge according to their nature. In order to become 
an aeroplane engineer and designer it is necessary to have a thorough knowledge 
of (a) the graphic representation of laws showing the relationships which .exist 
between the various quantities; (b) the fundamental theorems in theoretical 
mechanics, such as those dealing with velocity, acceleration, gravity, moments 
of inertia, centrifugal force, fluid motion, work, energy, and power; and (c) 
yarious theorems in applied mechanics in their bearing upon aeronautical problems. 
The first chapter of the book deals generally with the question of principles 
of design. Chapter 2 deals with constructional materials, including timber, light 
alloys, steel, and aeroplane fabric. Tables are given showing the standard specifi- 
eations for steel and the Brinell Hardness numbers, The method of preparing 
stress diagrams for the different components of an aeroplane is also lucidly 
explained. Chapter 3 is devoted to the proportions of aerofoils, and interesting 
descriptions are given of the experimental work carried out in the wind tunnels 
at the National Physical Laboratory and at the laboratories of Monsieur G. 
Wiffel, at Auteuil. Chapters 4, 5, and 6 deal respectively with Stresses and Strains 
in Aeroplane Components, Design of the Wings, and Resistance and Stream- 
lining. In chapter 7 problems connected with the Design of the Fuselage are 
considered, while the following two chapters deal respectively with the Design 
of the Chassis and of the Airscrew. The latter problem has been approached 
both by analytical and empirical methods. The method of analytical attack 
adopted by the authors is that known generally as the “blade element theory,” 
involving the consideration of the actual forces set up upon the blades, and based: 
upon laboratory experiments upon aerofoils. Chapter 10 deals with the question 
of stability, which is closely interconnected with the question of controlability; 
while Chapters 11 and 12 deal respectively with the Design of the Control Ser- 
vices and Performance. In Chapter 13 the principles enunciated are applied to 
the lay out of a complete machine, ; 
From the above it will be apparent that the whole subject is presented in a 
complete and logical manner. The yalue of the book is greatly enhanced by the 
inclusion of a large number of carefully prepared diagrams and tables which will 
prove of direct utility to persons engaged in aeroplane design. A special feature 
has also been made of illustrative examples, a large number of which are scat- 
tered throughout the text. In every way the volume is an excellent production. 
Modern Roads—By H. P. Boulnois, M.L.C.E., &c., London, Edward Arnold, 
1919. (Pp. vii. + 302.) In the preface the author states that he has endeavoured 
to deal with the subject of roads in as comprehensive a manner as is possible, 
bearing in mind the constant improyements in methods of modern road construc- 
tion that are now taking place. The first chapter deals generally with the import- 
ance of the road question, and it is pointed out that highway engineering is now 
a new profession involving knowledge of chemical and physical analysis, of the 
formation of the earth’s crust, and of the character and formation of its rocks, 
as well as of the location and construction of highways. This fact is too often 
overlooked in Australia. The other chapters of the book are devoted to Traffic, 
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