4 \ 
Reviews—The Mineral Industry of the British Empire. 431 
but these are vastly more numerous and, when the study of them is 
more complete, may prove to have as great geological importance 
and interest as the more sensational, and, at present, more fully 
studied, destructive shocks. We regret the omission of reference 
to Col. Harboe’s speculations on the nature of earthquake origins, 
as his studies seem to open up a line of research which is likely to 
lead to important results; and we notice that Dr. Davison, like almost 
every other writer, has failed to detect the logical flaw in Dutton’s 
method of determining the depth of origin, which results from the 
two-fold meaning attached to the word intensity, used in the 
formule as a measure of the amount of energy: transmitted over 
a unit of area in a unit of time, and in the application as synonymous 
with the acceleration of wave-particle. These are the only omissions 
of importance which we have noticed in a well-written, well-balanced, 
and adequate manual of a subject for which such an introduction 
was wanting and much needed. 
Tue Minerat Inpustry or tHe Britis Empire. Imperial 
Mineral Resources Bureau Handbooks: Manganese, pp. 151, 
3s. 6d.; Tungsten, pp. 44, 1s.; Coal, Coke, and By-Products, 
pp. 124, 3s. Si. 
HESKH pamphlets continue the plan of the preceding issues. 
Besides the necessary statistics the monographs on manganese 
and tungsten contain useful accounts of the geology and mineralogy 
of the deposits, with excellent bibliographies in each case. The 
volume on coal and its products deals mainly with statisties and the 
properties of different coals as fuel, and there is little to interest a 
geologist. 
Tae Tron anp Assoctatep Iypustries or LORRAINE, THE SARRE 
District, LuxemMBuRG, AND BreLaium. By A. H. Brooxs and 
M. F. La Crorx. Bull. 703, U.S.G.S., pp. 131, with 2 plates and 
12 text-figures. 1920. 
‘ips bulletin is mainly metallurgical, statistical, and political, 
but it includes a clear though brief account of the geology of 
the iron fields, which should be of value to those interested in the 
subject. There is a good bibliography, and a most useful feature is a 
large-scale folding map showing the geographical position of the iron 
and coal fields and their relation to the great industrial districts 
of Western Europe. The latest estimates show that France has 
now control of 48 per cent of the European iron-ore reserves, and 
for many years to come the Lorraine iron field must continue to be 
a dominant factor in European politics. Few people realize that the 
Jurassic system was the chief cause of the Great War. 
