March 20, 1902] 



NA TURE 



463 



OUR BOOK SHELF. 

 Tafelit ziir Theoretischen As/ronoinie. By Julius Bausch- 



inger. Pp. 148. (Leipzig : Wilhelm Engelmann, 



1901.) Price I2J. net. 

 Most astronomers are familiar with the very excellent 

 volume entitled " Formeln und Hiilfstafeln fiir Geo- 

 graphische Ortsbestimmungen," by Prof. Th. Albrecht ; 

 this work contains in a small compass most of the 

 forniula* and tables required for geodetic work, and the 

 very clear descriptions of the processes involved make 

 the volume a veritable vaii^ inectim for those employed 

 on such work. 



The volume before us does for " theoretical astronomy," 

 that is astronomy dealing with the determination of the 

 positions and orbits of bodies in space, what the above- 

 mentioned book does for geodetic work, and the main 

 attempt of the compiler has been to bring together in a 

 compact and complete form all that is required by the 

 computer, rendering it unnecessary for him to seek aid 

 from other books. In this class of work the computer 

 has generally to consult more than one volume in which 

 suitable tables for his calculations occur, such as, for 

 instance, the valuable work of von Oppolzer, and in some 

 cases the tables are not of the most convenient form. 



The present volume, therefore, serves a most useful 

 purpose, and the arrangement of the tables leaves, so far 

 as can be seen without actually working out a prob- 

 lem, little to be further desired. The tables, which 

 are forty-five in number, are arranged under six sub- 

 heads. The first of these divisions is devoted to such 

 objects as conversion of time into divisions of arc, mean 

 time into sidereal time, &c., and vice -i'ersd. The next is for 

 the determination of the true anomaly from the time and 

 vice versa, for elliptic, parabolic and hyperbolic motion, 

 and here three methods for the solution of Kepler's 

 equation are given ; two of them are based on Tietzen's 

 solution and are purely computational, while the third is 

 after the graphical method of Waterston and Dubois 

 and is accompanied by two loose charts. 



The third set of tables deals with the part of the 

 problem relating to the determination of the first ap- 

 proximate orbit, in which both Euler's and Lambert's 

 equations are required ; while this is followed by tables 

 which serve for the computation of special perturbations 

 and improvement of the elements determined by the first 

 approximation. 



The fifth part givfes the means for calculating preces- 

 sion, nutation, aberration and parallax, and contains a 

 list of the chief observatories of the world and their co- 

 ordinates, with data for parallax determination. 



The sixth and last section is formed of miscellaneous 

 tables which are of general use in work of this kind ; 

 thus we have formula; and tables for interpolation, differen- 

 tiation and integration, mechanical differentiation, cic, 

 concluding, amongst others, with mathematical, astro- 

 nomical and geodetic constants. 



All the tables which depend on astronomical constants 

 have been recalculated and based on the Paris Conference 

 constants, while each table is clearly explained and in 

 most cases accompanied by an example worked out step 

 by step. 



This book of tables will, with very little doubt, be of 

 considerable service both to the experienced computer 

 and to the student who is working out orbits for the first 

 time. Great praise is due to the compiler who has per- 

 formed this laborious task with so much care and with 

 such success. 

 An Elementary Treatise on Alternating Currents. By 



\V. G. Rhodes, M..Sc. (V'ict.). Pp. xii-l-211. (London: 



Longmans, Green and Co., 1902.) Price Ts. hd. net. 



Mr. Rhodes' treatise on alternating currents can hardly 



be regarded as particularly elementary, since he certainly 



assumes in his readers a preliminary acquaintance with 



NO. 1690, VOL. 65] 



the principles of the subject. We are inclined to think 

 that although the mathematical parts are good, the 

 treatment on the electrical side, especially in the simpler 

 parts, leaves a good deal to be desired. Thus on p. 23 

 the quantity 27r«L is defined as the reactance, whereas 

 a few pages further on (p. 31) this name is used for the 

 fuller expression including self-induction and capacity, 

 without any explanation as to why the same term is used 

 in both cases ; the same observations apply to the defi- 

 nition of impedance. One may be pardoned for laying 

 stress on such faults as these, since the subject is at best 

 a difficult one, and without a perfectly sound knowledge 

 of the fundamental ideas, the student will never make 

 much progress. 



The author has aimed at using the calculus as little as 

 possible, and, where its employment is inevitable, has 

 given the solution of an equation in the text and the 

 working in the appendix. Many of the problems are 

 solved by vector algebra, to an explanation of the prin- 

 ciples of which a short chapter is devoted. The design 

 of transformers and the theory of the synchronous motor 

 and polyphase currents are treated at some length. It 

 is to be noted that although hysteresis is of necessity 

 considered, it is nowhere adequately explained. Another 

 omission is that no description is given of any method 

 of determining the wave form of an alternating current 

 or P.D., although there is a chapter on the subject of 

 alternating measurements. We do not doubt that the 

 book will be found very useful, but its value would be 

 greatly increased by a more careful attention to 

 thoroughness and completeness. M. S. 



Cyanide Practice. By Alfred James, Member of the 



Institution of Mining and Metallurgy, F.G.S., F.C.S. 



Pp. xii -I- 174. (London: E. and F. N. Spon, Ltd. ; 



New York : Engineering and Mining Journal Incor- 

 porated. Not dated). Price 15^. net. 

 Although there are now a number of books in which 

 some information on the cyanide process can be found, a 

 full and satisfactory description of it has not yet been 

 written, and can hardly be expected until more experi- 

 ence has been gained. Meanwhile, no instalment of the 

 complete account can be more interesting and important 

 than that giving a record of the experience and views of 

 Mr. Alfred James. 



Mr. James was the pioneer of the process in South 

 Africa in 188S, and to him belongs the credit of adapting 

 it to the treatment of auriferous tailings at a time when 

 cyanide was in some danger of being set aside for the 

 time owing to the difficulties encountered in the treat- 

 ment of virgin ores with its aid. When a good start had 

 been made, and the value of cyanide solutions demon- 

 strated, a host of workers took up the task and a vast 

 industry was created on the foundations laid by Mr. 

 James ; but the part he played in promoting the pros- 

 perity of the Witwatersrand gold mines will always be 

 remembered with gratitude by metallurgists. 



As might be expected, the book is full of good things, 

 details of construction of vats and extractor boxes^useful 

 to the general manager, hints on extraction and precipita- 

 tion designed to aid the millman, and hitherto unpub- 

 lished researches on bromocyanide which will be read 

 with avidity by the chemist. The method of arrange- 

 ment, however, leaves something to be desired. Some 

 sections consist of papers read at various institutions 

 which have been reprinted almost without change and 

 without much effort to make them part of a coherent 

 whole. The imperfections of the index render it difficult 

 to refer to any particular point, and the only way to avoid 

 missing important details is to make oneself familiar with 

 the whole book, which is, fortunately, tersely written and 

 by no means long. Difficult as it may be, however, to 

 take full advantage of Mr. James's work, no one con- 

 cerned in the cyanide process can afford to do without 

 the volume which he has produced. 



