The Principles of Petrology. An Introduction to the Science of Rocks.: By G. W. Tyrrell,A.R.C.Sc., F.G.S., F.R.S.E., Ph.D. (Glasgow), Lecturer in Geology in the University of Glasgow. xii-349 pages, 78 figures,New York,E. P. Dutton and Company. Price, $3.25 |