RECENT ADVANCES IN SCIENCE 25 



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system, Ast. Nach. 207, No. 4966, 191 8. 

 LUNT, J., The Radial Velocities of 119 stars observed at the Cape, Astroph. 



Journ, 48, 261, 1918. 

 Campbell, W. W., The Total Solar Eclipse of June 8, 1918, Lick Obs. Bull. No. 



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1918. 



PHYSICS. By James Rice, M.A., University, Liverpool. 



Atom and Electron Structure. — The particular shape of the 

 electron, or fundamental unit of negative electricity, and the 

 distribution of the charge throughout the volume occupied by- 

 it, are matters which may be overlooked in the discussion of 

 many problems, where it is sufficiently accurate to regard the 

 electron as a " point charge." But, for the closer discussion 

 of those problems of atomic structure which are agitating the 

 minds of physicists to-day, no such simple view of electronic 

 structure is adequate. Discussion has, perhaps naturally, 

 centred most closely around an electron assumed to be spherical 

 or spheroidal in shape. In particular, Lorentz has made power- 

 ful use of the concept of an electron which, having a spherical 

 shape when at rest, suffers when in motion a contraction in 

 length in the direction parallel to its velocity and of an amount 

 1 : v 1 — v 2 /c 3 , where v is the electron's velocity and c is the 

 velocity of light. In fact, this assumption is but the logical 

 extension to these minute corpuscles of the Lorentz-Fitzgerald 

 contraction of matter in bulk — the hypothesis by which those 

 two physicists endeavoured to explain the failure of the 

 Michelson-Morley (and other) experiments to detect the 

 earth's motion through the ether. This " contractile " elec- 

 tron leads to a variation of mass with velocity which is in 

 extremely good agreement with the most trustworthy experi- 

 ments on /3 particles from radioactive materials and high- 

 speed cathode particles. 



As is well known, however, serious difficulty is being ex- 

 perienced to present a theory of atom structure which shall 



