NATURE 



[September 26, 1912 



method occasionally upsets the conventional sense 

 of proportion. Some of the things that we had 

 supposed really mattered are treated with indiffer- 

 ence ; a new sense of values is introduced. 

 Whether these will bear closer examination 

 remains to be seen, but in any case we may 

 warmly congratulate the author on the successful 

 completion of an arduous undertaking. 



J. A. G. 



ATOMIC DYNAMICS. 

 Prinzipien dcr Atomdynamik. By Prof. J. 

 Stark. I. Teil : "Die elektrischen Quanten." 

 Pp. X + 124. (Leipzig: S. Hirzel, 1910.) Price 

 3.20 marks. II. Teil: "Die elementare 

 Strahlung." Pp. xv + 286. (Leipzig : S. Hirzel, 

 191 1.) Price 7.80 marks. 



IN this work Prof. Stark gives a systematic 

 account of the experimental facts which 

 throw light on the constitution of the atom, and 

 develops a theory of the structure of the atom, 

 mainly on the basis of optical phenomena. The 

 work is divided into three parts. Part i. is in- 

 tended as an introduction, and deals with our 

 knowledge of the nature and properties of elec- 

 trons, and of the energy and structure of the 

 electromagnetic field. Little space is devoted to 

 the description of the methods by which the 

 experimental results were obtained, and more 

 prominence is given to the discussion of the 

 validity of the experiments and their value in 

 elucidating the internal structure of the atom. 



In chapter iii. the constitution of the atom on 

 Stark's theory is described. It is assumed that 

 electrons and positively charged entities (archions) 

 which are endowed with mass form the constituent 

 parts of an atom. On account of magnetic forces, 

 the archions form a definite configuration in the 

 atom, and cannot be separated without causing 

 its disruption. On the other hand, the electrons 

 which are attached to the archions can be separated 

 without causing the atom to decay. This atomic 

 system, which is more fully developed in part ii., 

 is capable of explaining and systematising many 

 of the experimental facts. 



The second part is mainly concerned with 

 electromagnetic radiation. After a discussion of 

 the theoretical principles of radiation, the grouping 

 of spectrum lines into series and the relations 

 existing between the frequencies of the lines are 

 considered. A detailed discussion of line and 

 band spectra and similar phenomena exhibited by 

 Rontgen rays is also given. The archion theory 

 is then worked out more fully, and hypotheses are 

 put forward to account for the origin of spectra. 

 The band spectra are ascribed to the vibrations 

 of the electrons which are attached to the archions, 

 NO. 2239, VOL. 90] 



while the archion itself, after losing the electron 

 attached to it, is the elementary oscillator respon- 

 sible for the line spectrum. The continuous 

 spectrum is ascribed to the vibrations of the free 

 electrons. These by frequent collisions suffer 

 irregular accelerations, and thus give rise to a 

 continuous succession of frequencies. A full and 

 interesting account of the bearing of the author's 

 theory on such problems as the Doppler effect in 

 canal rays, the Zeeman effect, fluorescence, and 

 allied phenomena is given. Also the results 

 obtained with Rontgen and y-rays are considered 

 in relation to the theory. 



The third part, which has not yet appeared, is, 

 according to a statement in the preface, mainly 

 intended for the chemist. It will deal with the 

 structure of the electromagnetic field on the sur- 

 face of chemical atoms, and with the forces which 

 hold the atoms together in chemical combinations. 



.\ work of this nature, which aims at a discus- 

 sion of the principles of atomic dynamics, must to 

 a large extent be of a speculative character. In 

 this connection, however, it is important to remem- 

 ber that the work always distinguishes very clearly 

 between experimental facts and speculative theory. 

 .Vlso, the reader who does not agree with the 

 speculations put forward in the work will find in it 

 a very useful record of all researches which con- 

 tribute to the elucidation of the internal structure 

 of the atom. Perhaps one misses a fuller discus- 

 sion of radioactive phenomena, which are inti- 

 mately connected with the problems discussed in 

 this work. Stark's book, which deals with such a 

 fascinating subject in an interesting manner, will 

 prove very useful as a guide to further research. 



H. G. 



MODERN ROAD CONSTRUCTION. 

 Modern Road Construction: a Practical Treatise 

 for the Use oj Engineers, Students, Members 

 of Local Authorities, <2^c. By Francis Wood. 

 Pp. xi+137; illustrated. (London: Charles 

 Griffin and Co., Ltd., 1912.) Price 45. 6d. net. 



THE conditions relating to the maintenance 

 of roads during the last few years have 

 undergone so much alteration, owing to the in- 

 troduction of motor vehicles, that the publication 

 of a practical treatise on the subject is fully 

 justified. 



The book now under notice cannot fail to be of 

 great service to those having charge of urban 

 roads. The author, who has the supervision of 

 the roads in the Borough of Fulham, appears to 

 have devoted a great deal of attention to observ- 

 ing and recording the wear and tear of different 

 kinds of material used ; and in obtaining statistics 

 as to their cost and endurance. The book gives, 



