526 Reviews—Products of the Empire. 
relating to markets, financial and political control and possibilities 
of future developments. 
The latter third of the book 1s occupied by chapters on exploration 
and development, conservation of mineral resources, valuation and 
taxation, the legal and international aspects of mineral resources, 
geology in war and in relation to engineering, and the training of 
the economic geologist. AJl these chapters contain admirable 
summaries of their subjects, and should be widely read. Perhaps of 
most interest are those on the national and international aspects of 
mineral resources. These are, of course, mainly written from the 
American standpoint, and it is striking to find that the United 
States, the oldest and greatest democracy, shows the least tendency 
of any country towards State ownership of minerals. Professor Leith 
gives some wise words of warning as to the dangers of subjecting 
industries of such paramount importance to the cumbrous, slow- 
moving, and unenterprising control of a bureaucracy. 
There is much wisdom, also, in his advice as to the training of 
the economic geologist ; he insists as strongly as possible on the 
necessity for a wide general education and a good grounding in pure 
science. In fact, his view amounts to this: “ Learn the pure science 
and the economic side will look after itself.” That is to say, the 
applications will be acquired gradually as a result of experience and 
practice. No man can tell beforehand in what particular subject 
he will specialize, and it is impossible to study them all in detail in 
an educational course. Nevertheless, much may be done by devoting 
special attention to the illustration of theory by examples of 
technical application, and teachers, by dealing fully with the theory 
underlying cases that are understood, may pave the way to the 
elucidation of others, of equal impertance, that are still involved 
in mystery. 
R. H. R. 
Propucts oF THE Empire. By 8. C: CunnineHam, B.A. pp. 299. 
Oxford, 1921. 
Piss little book aims apparently, and not unsuccessfully, at giving 
a short popular account of the assets of the British Empire 
in so far as these relate in the first place to food, drink, drugs, and 
tobacco, and in the second to raw materials and the produce of 
mines. As the author points out, there never has been a complete 
survey of all the Empire’s resources, but the Royal Commission 
appointed in 1912 has issued reports on the produce of cértain 
countries, and these have yielded much information of value. The 
chapters in this book which will be of most interest to the geologist 
are, naturally, those upon the metals, coal, and petroleum. The 
metallic produce is summarized in a useful table at the end of the 
second chapter on this part of the subject, and the sources of 
supply, both foreign and British, are duly set out; under the latter 
