December 29, 1916] 



SCIENCE 



905 



ler and others have shown that a general- 

 ized form of the Balmer equation, with 

 Rydberg's universal constant and a few 

 special constants, is capable of wide appli- 

 cation. Different combinations of a few 

 constants have been found to give a num- 

 ber of related series, and many new lines 

 so predicted have been found. The com- 

 mon limit and other numerical relation- 

 ships between different series of the same 

 element indicates that the different emis- 

 sion centers have some dynamic coupling 

 and Rydberg's universal constant indi- 

 cates a structural element common to all 

 substances. According to Bohr, this 

 quantity is a function of the electronic 

 and atomic mass, the elementary electrical 

 charge, and the wirkungsquantum h, and 

 should slightly increase with increasing 

 atomic weight. As it is commonly as- 

 sumed that it is an absolute constant, care- 

 ful measurements may furnish a test of the 

 validity of Bohr's theory. 



The relationships of frequency to atomic 

 number found by Moseley recalls that 

 Ramage, Watts, Runge and Precht and 

 Hicks have found linear relationships be- 

 tween the squares of the atomic weights 

 and the frequencies or frequency differ- 

 ences of homologous lines in the spectra of 

 elements of the same group. Ives and 

 Stuhlmann have shown that in some cases 

 the results are improved by substituting 

 atomic numbers for atomic weights, but the 

 relationship is evidently not so simple as 

 in the case of X-ray spectra. 



The discovery of the Zeeman effect and 

 the explanation of its simpler forms by 

 Lorentz was the first step toward a ra- 

 tional spectroscopic theory. The later dis- 

 covered complexities and anomalies, while 

 they may defy mathematical analysis, do 

 not lessen our confidence in the theory, for 

 they are what we might expect as a result 

 of complicated atomic structure. The 

 same intellectual satisfaction does not at- 



tend the discovery of the analogous effect 

 of an electric field, because the simplest 

 cases are so complex that they can not be 

 adequately explained by any theory yet 

 proposed. The possibility of such an effect 

 had long been the subject of speculation, 

 but Stark was the first to realize and at- 

 tain the necessary conditions for its oc- 

 currence. Lo Surdo also discovered it in 

 the neighborhood of the cathode in capil- 

 lary tubes. As in the case of the Zeeman 

 effect, the phenomena are different when 

 viewed transversely and parallel to the 

 field. In each case the lines are split into 

 a number of components, the number be- 

 ing different for different lines, even for 

 those belonging to the same series. In the 

 transverse effect the components are plane- 

 polarized in hydrogen and helium, the 

 stronger central lines vibrating at right 

 angles to the field, and the stronger outer 

 components vibrating parallel to the field. 

 A remarkable relation is found for the 

 series lines of hydrogen, helium and 

 lithium. For each the number of princi- 

 pal normal components appears to be equal 

 to the ordinal number of the line in the 

 series. Higher dispersion shows that in 

 the case of hydrogen each component is 

 double. If this rule holds good through- 

 out the series, the last known line, the 

 twenty-eighth, would have 56 such com- 

 ponents, an equal number polarized at 

 right angles to these, and a number of 

 weaker components of both kinds — truly 

 a formidably complicated system. In gen- 

 eral the longitudinal components appear 

 to be unpolarized, although Miss Howell 

 has found some anomalies with lithium 

 and calcium. In some cases the compo- 

 nents are unsynunetrical both in position 

 and in intensity. Of all the other elements 

 investigated, mercury alone shows a slight 

 broadening. It might be expected that the 

 great nuclear charges of heavy atoms 

 would diminish the effect of an external 



