276 



SCIENCE 



[N. S. Vol. XLVI. No. 1186 



current, it therefore will be assumed that 

 the atom's magnetic field is due to orbitally 

 revolving rings of electrons, subject to tem- 

 porary bunehings or other disturbances, 

 possibly the shift of an electron from one 

 ring to another, that render the ring so dis- 

 turbed, or the shifting electron, radiative 

 during the brief interval in which equilib- 

 rium is being regained. 



Let V be the velocity of light, A the wave- 

 length of the emitted radiation, m the angu- 

 lar velocity of the electrons as seen from 

 the center of the orbit, S the average 

 strength of the enclosed magnetic field, K 

 a constant and n a whole number, perhaps 

 unity. Then 



Hence 



vdX 



From (1) and (2) 



= KS. 



d3 

 ' s ■ 



(1) 



(2) 



But dS is added to the fields of some atoms 

 and subtracted from the fields of others by 

 the application of an external magnetic 

 field of strength 3 to any mass of gas. 

 Hence 



d\ H 



By substituting H for dS m (2) we get 



d\ K 



-F=-r = — , a constant. 

 H\- V 



But this is the well-known Zeeman law, 

 and therefore it appears that the assumed 

 simple structure of the atom must at least 

 crudely resemble its actual structure. 



From the known values of H, X and dk 

 the computed value of S, the average 

 strength of the atomic magnetic field, is of 

 the order of 10^ gauss. 



Similarly from the probable size of the 

 atom, radius =10"^ em., and the charge of 



the electron it is easy to calculate the mag- 

 netic field at the center of the ring system 

 on any definite assumption of the speed of 

 rotation and number of electrons. 



If it is assumed that the period of rota- 

 tion is the same as that of the emitted radi- 

 ation, and that N, the number of electrons 

 in the atom, is of the order 



in which A is the atomic weight, a number 

 many investigators regard as probable, then 

 the computed intensity of the magnetic 

 field at the center of an iron, titanium, or 

 other such atom is of the order of 10', 

 roughly 2,000 times the most intense field 

 yet produced between the poles of electro- 

 magnets. 



Wliatever the strengths of these fields, 

 each atom must act inductively on all its 

 neighbors and in turn be acted upon by 

 them, to an extent that for each couple 

 varies approximately as the cube of the dis- 

 tance between their centers. If two atoms 

 in the turmoil of the electric arc, for in- 

 stance, chance closely to approach with 

 similar poles facing each other their mutual 

 induction will be such as to increase the 

 speed of their electrons, and thus for the 

 instant sliglitly to shift their spectrum lines 

 to the violet. If, however, they approach 

 with opposite poles facing each other the 

 shift will be to the red. But in the second 

 case the atoms clearly will come closer to- 

 gether, thus producing stronger inductions 

 and greater shifts, than in the first. Hence 

 the net result is a displacement of the maxi- 

 mum intensity of the line to the red. 



When the gas pressure about the light 

 source, an electric arc, suppose, is low the 

 distance between neighboring atoms is rela- 

 tively large and therefore during only a 

 correspondingly small fractionof the time is 

 any given atom under the strong inductive 

 influence of others. During the rest of the 



