March i 8, 1909] 



NATURE 



In discussing the strength of struts, the author 

 [mints out that the chief difficult\- in dealing with 

 .struts lies in ihe choice of the safe stresses per square 

 inch for various values of the buckling factor, and the 

 effects of eccentric loading of stanchions illustrate how 

 desirable it is to have the load as central as possible. 

 Jn the chapter devoted to masonr}- structures, there is 

 ;i good deal of matter not usually found in text-books, 

 and a brief reference is given to the recent develop- 

 ments of the theory of stresses in masonry dams, due 

 to the original researches of Prof. Karl Pearson ; and, 

 in deducing formulse for the strength of retaining 

 walls, three theories are explained — the Rankine, the 

 wedge, and the Scheffler. 



In dealing with the subject of reinforced concrete, 

 (lie author points out that a great deal of experimental 

 work is still required in this direction before the 

 principles underlying design shall bo established on a 

 sure and certain foundation, and he points out the 

 danger of the uninitiated using data obtained from 

 iin<'stigations on materials quite different from those 

 wliicli he proposes to use in his own design. The last 

 threo chapters are devoted to designs of steel work 

 for various buildings, roofs and bridges, and a 

 juimber of excellent practical details are given, and 

 illustrations of recent structural steel work. 



Th'.s book undoubtedly marks a considerable im- 

 provement in the type of text-book which has recently 

 been placed at the disposal of engineering students 

 in connection with the theory and design of struc- 

 tures. There are original methods of dealing with 

 problems, the theory is in all cases unimpeachable, and 

 the numerous examples selected for illustrating these 

 various theories have been chosen with admirable 

 judgment. The book, however, is more than a mere 

 text-book for students; it will be found of consider- 

 able use by draughtsmen and engineers who are en- 

 gaged in constructional steel and iron work. 



(i) Though this book has been written mainly for 

 engineering students, and from the point of view 

 of university examinations, it will undoubtedh' prove 

 most useful to practical engineers. So many text- 

 books have now been written on this subject that it 

 becomes extremely difficult for an author to embody 

 anything strikingly original. Prof. Morley has, how- 

 ever, devoted considerable attention to several branches 

 of the subject which are ordinarily passed over, or only 

 briefly touched upon in most of the works dealing 

 with the subject of strength of materials. 



In chapter ii. there is a resume of the theories 

 which are held as to whether or not, in cases other 

 than simple direct stresses, the breaking down of a 

 bar in a machine or structure occurs for a certain 

 value of the maximum principal stress, for a certain 

 value of the maximum principal strain, or for a 

 i.-trtain value of the maximum shearing stress. 

 .Throughout the book the first of these theories is 

 generally employed, but its use has to be justified by 

 the choice of a factor of safety which is reckoned 

 on the ultimate and not on the elastic strength of the 

 material, and which must be varied according to 

 circumstances. 



In chapter xii., the problems involved in the 

 NO. 2055, VOL. 80] • 



strength of rotating discs and cylinders are fully in- 

 vestigated, and also the bending of originally curved 

 bars, such as crane hooks, for example. The strength 

 of flat plates is treated in chapter xiii. in a very 

 complete manner by means of the Bernouilli-Euler 

 theory of bending, with such modifications as are 

 required to allow for flexure in other than a single 

 plane. Another useful chapter is that devoted to the 

 subject of vibrations and critical speeds, in which is 

 incorporated the results of Prof. Dunkerley's re- 

 searches on the whirling speed of rotating shafts. In 

 chapter xvi., Prof. Morley has given descriptions of a 

 number of the special testing machines which have 

 been introduced in recent years for impact and hard- 

 ness tests, and copious references have been given to 

 the memoirs which have been published dealing with 

 researches and investigations undertaken with the aid 

 of these special machines. 



Every chapter contains a number of fuUy-worked- 

 out examples, and there is a good selection of ex- 

 amples for practice by the student, and, in the form 

 of an appendix, are given tables of logarithms, such 

 as would be required in the working out of these 

 e.xamples. 



The book is a valuable addition to the library of 

 the engineer who has to undertake the calculation 

 of the stresses and strains in machinery and 

 structures. 



WIRELESS TELEGRAPHY. 



An Elementary Manual of Radio-telegraphy and 

 Radio-telephony for Students and Operators. By 

 Dr. J. A. Fleming, F.R.S. Pp. xiv + 340. (London : 

 Longmans, Green, and Co., 1908.) Price 75. 6d. 

 net. 



La Telegraphie sans Fil et les Applications pratiques 

 des Ondes electriques. By Albert Turpain. Second 

 edition. Pp. xi-l-396. (Paris: Gauthier-Villars, 

 1908.) Price 9 francs. 



Jalirbuch der drahtlosen Telegraphie und Telephonie. 

 \"ol i., part iv. Edited by Dr. Gustav Eichorn. 

 (Leipzig : Verlag von S. Hirzel, 1908.) 



WE have already had occasion to review in these 

 columns Dr. Fleming's treatise on " The 

 Principles of Electric Wave Telegraphy," and at the 

 time we expressed the opinion that that treatise not 

 only admirably filled a gap in the literature of the 

 subject, but deserved to rank as the most important, 

 if not the only, book on wireless telegraphy which 

 students need consult. It must be frankly admitted, 

 however, that by writing the present manual Dr. 

 Fleming has performed another service to this branch 

 of electrotechnology, in the exposition of which he 

 stands, certainly in this country and probably in any 

 country, easily first. The former treatise was pos- 

 sibly too exhaustive and in parts toe difficult for those 

 who had not the ability or inclination to study the 

 subject thoroughly. It must be remembered that 

 wireless telegraphy has become in recent years a 

 department of applied electricity of great practical 

 importance, offering a steadily increasing field of 

 cmjjloyment for large numbers of men. The majority 



