Jaxuakv 7, 19C9J 



NA TURE 



277 



ELEMEXTAK Y MATHEMATICS. 

 (i) Elcineiilary Solid Geometry, including the Men- 

 suration of the Simpler Solids. By \V. H. Jackson. 

 Pp. xii+159. (London: Edward Arnold, 1907.) 

 Price 2S. 6d. 

 (2) Euclid Simplified in Accordance ivilh tlie jYezy 

 Uni-cersity Regulations, it'ith Additional Propositions 

 and Numerous Examples. Fourth edition. By 

 .Saradaranjan Ray. Pp. xvi+271. (Calcutta : The 

 City Book Society.) Price 1.8 rupees. 

 (0 .1 Preliminary Geometry. By Noel .S. Lydon. 

 Pp. iv+io8. (London: Methuen and Co., n.d.) 

 Price IS. 

 (4) Examples in Elementary Meclianics, Practical, 

 Graphical, and Theoretical. By W. J. Dobbs. 

 Pp. .\ii + 344. (London : Methuen and Co., n.d.) 

 Price 5^. 

 (i) ' I ■'HE study of tliree-dimensional geometry is 

 -L generally more or less neglected in our 

 schools ; this excellent text-book should materially help 

 to correct this fault ; its effect on the reader is to 

 enhance his sense of the importance and attractive 

 nature of the subject. In part i. the properties of the 

 line and plane and of the simpler curved surfaces are 

 demonstrated with Euclidean rigour, but with a de- 

 lightful freshness which recent reforms have done so 

 much to encourage. Moreover, the numerous and 

 well-chosen exercises, and the admirable figures and 

 di.igrams, are quite a feature of the book. Part ii. 

 deals with the mensuration of solids. It is as effective 

 as before ; in style and treatment and in the diagrams 

 and exercises the same high standard is maintained. 

 Prof. Horace Lamb has written an appreciative pre- 

 f.ice, and there is no book on this branch of mathe- 

 ni.atics more worthv of adoption in our schools and 

 colleges. 



(2) In this geometry, in order to preserve con- 

 tinuity and for convenience of reference, the sequence 

 .and indeed the numbering of Euclid's propositions are 

 maintained, while the arrangement is designed to 

 meet the requirements of the new syllabus of geometry 

 for the matriculation examination of the Calcutta 

 L niversity, which will be found very similar to the 

 schedules now prevailing in this country. In re- 

 modelling Euclid according to this scheme, proposi- 

 tions of minor importance are relegated to the 

 exercises, and new propositions are added. The 

 enunciations and proofs are revised and often re- 

 written. Many exercises are provided. The book will 

 ap|)eal to those who wish to follow the new methods 

 with as little departure from the old as possible, and 

 who are not prepared to accept the reform in its 

 entirety. 



(3) This useful little book gives a simple and orderly 

 course of practical geometry for beginners, intended 

 as a preliminary to a formal and deductive study of 

 the subject. The pupil becomes acquainted with the 

 terminology and with the properties of the simpler 

 plane figures, and to some extent is trained to use his 

 reasoning faculties. The author is very successful in 

 carrying out his scheme. 



(4) The distinction between theoretical and applied 



NO. 2045, VOL. 79] 



mechanics is gradually losing its significance, and it is 

 now generally recognised that the subject of mechanics 

 cannot be satisfactorily taught without some amount 

 of experimental and practical work done by the student 

 himself. The present book is written from this point 

 of view ; the graduated series of examples, arranged 

 in chapters, are experimental, mmierical and graphical, 

 and aie accompanied by just sufficient explanation and 

 discussion of principles as, with the guidance of a 

 teacher, will enable the student to dispense with an 

 ordinary text-book. The apparatus used, while effec- 

 tive for its purpose, is of the simplest character, and 

 is for the most part made by the student himself. 

 Statics is fully discussed before dynamics is taken up, 

 a sequence which, we think, is the right one. The 

 conception is good and well worked out, and the book 

 will commend itself to many teachers. 



TWO SPECULATIVE CONTRIBUTIONS TO 



GEOLOGY. 



Die Entstehung der Konti)iente, der I'ulkaiie und 



Gebirge. By P. O. Kohler. Pp. vi + 58; 2 figures. 



(Leipzig : W. Engelmann, igoS.) Price 1.60 marks. 

 Die geologischen Grundlagen der Ahstammungslehre. 



By G. Steinmann. Pp. ix+284; 172 figures. 



(Leipzig : W. Engelmann, 1908.) Price 7 marks. 

 ' I "HESE two books have little in common except 

 -'- that they are both German speculative discus- 

 sions of geological principles. Herr P. O. Kohler's 

 pamphlet on the origin of continents, volcanoes, and 

 mountains is a contribution to dynamical geology, in 

 which he rejects some of the most generally accepted 

 facts in geological morphology, and opposes especially 

 some of the main conclusions of Prof. Suess. The 

 author denies the existence of " Senkungsfelder," or 

 foundered blocks of the earth's crust, and he declares 

 that raised earth blocks — the Schollen of Suess — are 

 statically impossible. Herr Kohler regards plutonic 

 and volcanic intrusions as closely allied, and attaches 

 great weight to the extent of plutonic activity ; he 

 describes the views of those whom he calls the 

 " passive plutonists " as erroneous in all important 

 respects, and he traces their errors to two chief 

 fallacies — the secular cooling of the earth and its 

 higher internal temperature. 



Prof. Steinmann 's book is a bold attempt to re- 

 classify the animal and vegetable kingdoms. He 

 advocates principles which, if not altogether new, 

 have long been out of fashion and lead to startling 

 and incredible results. Twenty years ago Prof. 

 .Steinmann was driven to study the bases of the current 

 theory of phylogeny, as it would not fit the facts ; 

 and in this volume he gives a most interesting sketch 

 of the history of the subject, followed by a statement 

 of the principles and results obtained by his own long 

 studies. Most palaeontologists share Prof. Stein- 

 mann 's faith in the importance of the historic 

 evidence. The positive records of geology as to the 

 succession of life on the world afford the ultimate 

 test by which all theories of evolution must be judged. 

 .V sufficient volume of evidence may not be collected 



