484 



SCIENCE 



[N. S. Vol. XXXVI. No. 928 



ungen der Deutsclien Siidpolar Expedition 

 1901 bis 1903," Fr. Bidlingmaier ; " Eegard- 

 ing Magnetic Records Obtained in Cooperation 

 with Captain Scott's Antarctic Expedition," 

 C. Chree; " Magnetic Character of Days as 

 Observed at the Cheltenham Magnetic Observ- 

 atory, April 1 to June 30, 1912," G. M. T., O. 

 H. Tittmann ; " The Magnetic Character of 

 the Year 1911," G. van Dijk ; " Leve Mag- 

 netique der Bassin du Eio S. Francisco," H. 

 Morize ; " Observation of the Magnetic Decli- 

 nation at Warsav7 during the Solar Eclipse of 

 April 17, 1912," S. Kalinowski; "On the 

 Movement of Inertia of Long Magnet H 26 at 

 the Cheltenham Magnetic Observatory," E. L. 

 Faris; Abstracts and Eeviews. 



SCIENTIFIC BOOKS 

 The Influence of a Magnetic Field upon the 



Sparh Spectra of Iron and Titanium. By 



Arthur S. King. Publication No. 153. 



Carnegie Institution of Washington. 



It is assumed that the readers are familiar 

 with line spectra produced by luminous rays 

 from dissociated particles of the metals. 

 Most readers vrill also be familiar v^ith the 

 following fact, viz., when these lines are pro- 

 duced in a magnetic field they break up into 

 three or more components. This is called the 

 Zeeman effect. 



By reason of Hale's epoch-making discov- 

 ery of a Zeeman effect in solar lines, this phe- 

 nomenon has come to have a large interest to 

 astrophysicists as well as to physicists. This 

 iron and titanium study should particularly 

 appeal to the former. 



The Zeeman effect is much more compli- 

 cated than the simple theory first indicated. 

 The separations differ in magnitude, number 

 of components, relative spacing of the com- 

 ponents, relative intensity and relative sharp- 

 ness. Farther, the intensity of some of the 

 components is relatively increased (enhanced) 

 with respect to the original line, others are 

 relatively decreased. All of these items are 

 important in the determination of spectral 

 series and in arriving at the physical condi- 

 tion of the luminous particles. Each spectral 

 series generally shows but one type of sepa- 



ration. Furthermore, some of these types re- 

 peat from substance to substance, showing an 

 intimate electronic relationship in the mole- 

 cule of different substances. The phenomenon 

 grows very complex in the detailed study of 

 the different elements. The " Zeeman effect " 

 and spectral series stand almost alone in 

 showing us what a wonderful complex struc- 

 ture exists within every atom. Not all the 

 complexities of the phenomena have been ex- 

 plained. Still, theory has kept well apace with 

 the observations and has often pointed out 

 the way. So important in the latter respect 

 has been some of the contributions by Eitz, 

 that I should like to add at least one of his 

 contributions' to the very complete bibliog- 

 raphy given by Mr. King. 



While all the above characteristics are im- 

 portant no observer has recorded them all, not 

 caring to encumber his data with detail which 

 is not immediately fruitful. Likewise there 

 is much curtailing of the computations. In 

 a paper published by the Carnegie Institution, 

 it seems to me that items of possible future 

 as well as present value might be recorded 

 and save a great amount of labor. 



The components of many lines lie so very 

 close together that it is necessary to separate 

 the two kinds of vibrations by some polarizing 

 device, and photograph each separately. The 

 very important relation of the intensity of 

 these kinds of vibration can not then be 

 found accurately since it is impossible to 

 maintain light at the same intensity for the 

 two exposures. But it occurs to me that, with 

 the non-astigmatic Littrow spectroscope 

 which Mr. King has used, one could focus the 

 double image of an interposed calcite upon 

 the slit and photograph both kinds of vibra- 

 tions coincidently in juxtaposition. 



Particularly among the several component 

 lines, there seems to be a certain degree of 

 order. They are often stepped off in uniform 

 spaces. These steps differ in magnitude from 

 line to line, but all seem to be simple frac- 

 tional parts of a standard value, called the 

 normal, a. Furthermore, this " normal " has 

 the value we should expect from the ratio of 



^Ann. d. Physik, 25, 660, 1908. 



