REVIEWS 681 



and Dewar were amongst the earliest investigators in discovering the existence of 

 homologous series of lines in spectra, and of groups of lines alternately sharp and 

 diffuse, results which foreshadowed the later developments. Then there are 

 important investigations on wave-lengths of lines in the ultra-violet in the spectra 

 of many elements, and on the reversal of spectral lines. A few of the other 

 matters dealt with are origin and identity of spectra, the nature and temperature 

 of sun-spots, the influence of pressure on spectra, problems of the atmosphere, the 

 separation of the inert gases in the atmosphere, and studies of their spectra. 



The papers are arranged— with but few exceptions, the reason for which is not 

 quite clear— in chronological order. A supplementary and hitherto unpublished 

 paper is added, " On the separation of gases by electric discharges with various 

 electrodes." The classified subject index at the end, " the work of an amateur," 

 is very well compiled, the references being full and complete, and will enable the 

 work done on any particular point to be referred to at once. An authors' index has 

 also been added. 



The work of Liveing and Dewar is a striking example of scientific collaboration, 

 and this volume is a fitting tribute to the value of their united labours. 



H. S. J. 



Resolution cf Planck's Constant and Rydberg's Constant, and the Origin and 

 Inter-relations of Spectra Series. By Jas. Stewart. [Pp. 16.] 

 (Paisley: J. & R. Parlane, 191 5. Price is. net.) 

 The author claims in this pamphlet to have established relations between the 

 mass and charge of an electron, the velocity of light, Planck's constant h which 

 occurs in the law of black-body radiation, and Rydberg's well-known universal 

 constant, N, which enters into his formulae for spectral series. From these rela- 

 tions, if two of these quantities are known, the others may be calculated, and 

 assuming the accepted value of the electronic charge and Curtis's determination of 

 N, the author proceeds to calculate the other quantities, and obtains results in fair 

 agreement with experiment. Equally good agreements, however, have been 

 obtained previously in other ways, and in the present instance they must certainly 

 be regarded as fictitious, being based upon hypotheses and suppositions for which 

 no justification is given except that the results obtained by using them are the 

 correct ones. In addition to this, the equation of the motion of the rotating 

 electron upon which the theory is based is incorrect, and altogether neglects the 

 existence of a magnetic field around the electron. 



The second part of the pamphlet, dealing with the origin and inter-relation of 

 spectral series, possesses no more solid foundation than that of the first part, and 



is not worthy of serious consideration. 



H. S. J. 



PHYSICS 



(a) Numerical Examples in Physics. By H. S. Jones, M.A. [Pp. xii + 332.] 



(London : G. Bell & Sons. Price 3*. 6d.) 

 {b) Statics. Part II. By R. C Fawdry, M.A., B.Sc. [Pp. 159-305-] (London: 



G. Bell & Sons, 191 5. Price 2s. net.) 

 (c) A Manual of Mechanics and Heat. By R. A. Gregory and H. E. Hadley, 



B.Sc. [Pp. viii -f 309.] (London : Macmillan & Co. Price 3J. net.) 



(a) The average student of Physics called upon periodically to face examination 

 papers which contain numerical questions will find this book a veritable store- 

 house of questions of all types relating to the various parts of the subject. The 



