6go 



NA TURE 



[November 25, 1922 



opinion. Sir William Ridgeway repeats an old 

 challenge to the supporters of the House of Residents 

 to cite a case where the Senate has outvoted the local 

 body. There may be only one case, the recent com- 

 promise on the admission of women to the University. 

 But the charge against the Senate's vote is that, as is 

 perhaps only too natural with the older members of the 

 University, the Senate's vote is consistently and 

 steadily against change— or, if an alternative is pre- 

 sented, for the least possible change offered to its 

 choice. Its control is capricious in so far as its inter- 

 vention is made at the capricious decision of a body of 

 resident conservatives who, through the Senate, wield 

 a wholly disproportionate power on matters vitally 

 affecting the well-being of the University. 



The Study of Spectra. 



The Physical Society of Loudon. Report on Series in 

 Line Spectra. By Prof. A. Fowler. Pp. vii + 183 + 5 

 plates. (London : The Fleetway Press, Ltd., 1922.) 

 125. 6d. 



A Treatise on the Analysis of Spectra : Based on an 

 Essay to which the Adams Prize was awarded in 1021 . 

 By Prof . W. M. Hicks. Pp. viii + 326. (Cambridge: 

 At the University Press, 1922.) 355. net. 



OF the two works now under notice, the first, by 

 Prof. Fowler, is the third of the series of 

 reports published by the Physical Society, its pre- 

 decessors being those by Dr. Jeans on Radiation, and 

 by Prof. Eddington on the Relativity theory. These 

 set a very high standard, but the present work worthily 

 maintains it, and we are glad, at the outset, to offer 

 congratulations to the Physical Society on the con- 

 tinued service which it is rendering to science by their 

 publication. 



The choice of subjects for these reports has been 

 singularly happy. The first two dealt with the matters 

 which, at the time, were most prominently in course 

 of development. This third report has at least ,111 

 equal claim to attention on a somewhat different 

 ground. The remaining problem which is most out- 

 standing, both for the physicist and chemist, and 

 indeed for every scientific man, is that of the structure 

 of the atom. Clues towards its comprehension are 

 provided on every hand by the practical and statistical 

 workers ; but they never become final in their 

 importance. After Balmer formulated his well- 

 known expression for the hydrogen spectrum as an 

 orderly arrangement, at least eight model atoms, 

 constructed on entirely different principles, have been 

 used to deduce it theoretically. Its simplicity alone 

 1 ondemns it as a decisive factor in our knowledge, and 



no. 2769, vol. no] 



the practical worker, who shows us that, even arti- 

 ficially, elements can be broken up, takes us no further 

 towards the formulation of the fundamental dynamical 

 principles, all-embracing in their scope, which deter- 

 mine the behaviour and structure of an individual 

 atom, once and for all, when we know the charge on 

 its nucleus and the number of electrons pursuing their 

 orbits. 



The study of spectra must provide the final test of 

 any atomic theory. Spectra can be measured with an 

 accuracy far transcending that obtained in any other 

 phenomena which bring us into touch with an indi- 

 vidual atom, and spectra have never been measured 

 systematically by any worker with the general accuracy 

 obtained by the author of the present report. A 

 remarkable part of the work described in this report 

 is due to Prof. Fowler himself, not only in respect of 

 the accuracy of measurement, but even more as regards 

 the elucidation of the nature of the spectra and the 

 conditions which regulate their appearance in the 

 laboratory or in celestial bodies. 



For many years spectroscopists have been at a great 

 disadvantage. All the literature of their subject has 

 been scattered, and a general compendium, written by 

 one in the forefront of progress, has been perhaps the 

 most urgent need of the physicist whose aim is the 

 direct determination of the laws governing the motions 

 in an atom of any element more complex than hydrogen. 

 In the last resort, the test of a theory of any 

 chemical atom is that its possible radiations can be 

 determined, by pure mathematical analysis, as specific 

 numbers with a degree of accuracy of at least one 

 part in 10,000, which shall preclude any possible 

 fortuitous coincidence. In certain cases this appears 

 to have been done. Nicholson's investigation of the 

 coronal spectrum, and Bohr's theory of the hydrogen 

 and charged-helium spectrum, together with Wilson's 

 and Sommerfeld's remarkable determination of the 

 appropriate generalisation for elliptic paths of the 

 electrons, appear, for example, to meet this necessity. 

 But all such investigations are preliminary only, and 

 nothing is certain till a more complex spectrum is so 

 elucidated. 



The material for such a generalised treatment of the 

 quantum theory is presented in full detail by Prof. 

 Fowler. The treatment is very lucid and this work 

 will completely replace the more usual but out-of-date 

 accounts, which the spectroscopist now has in his 

 library. The present work may be expected to mark 

 a definite epoch in the history of atomic theory as well 

 as of spectra in their more limited scope. 



The author, like Prof. Hicks in the other work under 

 notice, is not concerned with particular theories. In 

 a certain sense, however, Prof. Hicks is so concerned, 



