474 



NATURE 



[April 15, 1922 



normal correlation surface conclude the volume. An 

 appendix of some sixteen pages deals with a number of 

 incidental points, and short notes are given on certain 

 current sources of social statistics and on tables as aids 

 to calculation. 



The book seems very competently done, and we 

 have noted few points for criticism that are worthy of 

 individual comment. 



A criticism of a general kind may, however, be made, 

 namely, that the author has not kept in mind sufficiently 

 carefully the type of reader whom he is addressing. 

 The initial chapters of Part I. are written in a very 

 simple style, adapted to a reader of little ability and 

 practically no mathematical knowledge ; but in the 

 chapters on correlation differentiation is used, and in 

 Part II., when Prof. Pearson's curves are explained, 

 the reader will require a fair knowledge of and ability 

 to use the calculus. The result is that parts of the 

 book are beyond the elementary reader, and others 

 almost too elementary in style for the more able 

 student. It should, however, prove a useful addition 

 to the small, but growing, number of books on the 

 theory of statistics, for the same ground is not covered 

 by any other volume. The printing and general get- 

 up of the book are admirable, but author and editor 

 of the series are to blame for not including an index. 



G. U. Y. 



Surveying for Oil Geologists. 



(i) Field Mapping for the Oil Geologist. By C. A. 

 Warner. Pp. x + 145. (New York: J. Wiley and 

 Sons, Inc. ; London : Chapman and Hall, Ltd., 

 1921.) ly. 6d. net. 



(2) Field Methods in Petroleum Geology. By Dr. 

 G. H. Cox, Prof. C. L. Dake, and Prof. G. A. Muilen- 

 burg. Pp. xiv + 305 + ii plates. (New York and 

 London : McGraw-Hill Book Company, Inc., 1921.) 

 24s. net. 



THE great increase in the demand for combined 

 geological and topographic mapping of oil- 

 fields has led to the issue of books to teach the rudi- 

 ments of geology to surveyors and of surveying to the 

 geologist. These two manuals belong to this group, 

 (i) The smaller, by Warner, is written with special 

 reference to the conditions of the central oilfields of 

 the United States, and it includes tabular summaries 

 of their geological sections. The geology is otherwise 

 so elementary that no oil company would be well 

 advised to trust to geological surveys by men whose 

 knowledge of the subject is so limited that they would 

 gain any help from the chapters thereon in this book. 

 Its concise mathematical tables, simple explanations 

 of surveying methods, instructions for the preparation 

 NO. 2737, VOL. 109] 



of convergence maps and for the verification of oil 

 scums on seepages, may, however, render jt useful to 

 geologists who have had no special training in oil 

 prospecting and may be called on to take part in this 

 work. 



(2) The work by Messrs. Cox, Dake, and Muilenburg, 

 three professors of the Missouri School of Mining and 

 Metallurgy, is a larger work, and its geology is more 

 advanced. The mathematical tables are fuller, and 

 the account of geological structures may be read with 

 great advantage by students of geology in schools 

 which do not give much attention to the structural 

 side of the subject. It has an admirable glossary, 

 which explains among other facts that the term " wild- 

 cat " in oil mining is not the same term of contempt as 

 in metal mining, as it is applied to all well-sinking in 

 unproved territory. This development of the term 

 suggests that American opinion regards all oil boring 

 in unproved ground as so speculative that the expression 

 is used for it which the metal miner adopted for forlorn 

 hopes and reckless gambling. In a book in which con- 

 ciseness is so indispensable it seems unnecessary to 

 have included the history of the mariner's compass 

 and of the barometer. 



Neither book gives any help in the use of fossils. 

 The Missouri manual refers to fossils as if their evidence 

 were too difficult for use by any but an expert ; con- 

 sidering, however, the importance of fossils in oil work 

 and the value of the indications often given by the 

 simplest of palseontological evidence, some instructions 

 how to recognise and collect fossils might usefully have 

 been included. 



The Fourth Dimension. 



The Fourth Dimension Simply Explained. A Collection 

 of Essays selected from those submitted in The 

 Scientific American's Competition. Pp. 251. 

 (London : Methuen & Co., Ltd., 192 1.) js. 6d. net. 



THE fourth dimension and non-Euclidean geometry 

 have achieved a prominence quite unprecedented 

 for mathematical topics. In train, bus and tram, over 

 lunch and at the theatre, intelligent man is discussing 

 the fundamentals of his physical consciousness. Mathe- 

 maticians have sprung a surprise on the man in the 

 street — and on one another, and the former has some 

 reason to complain. He remembers, perhaps with 

 pain, the tyrannical ukases of Euclid, and, if he did 

 not acquire an enthusiastic love for the old Greek, 

 he was at any rate pleased to think that the puzzles 

 of geometry had been settled by something approximat- 

 ing to incontrovertible authority ; he was grateful 

 that he need not worry about the doctrine of parallels, 

 or the three angles of a triangle, or about the up and 



