Smi-thsonian Report, 1902, — Becquerel. 



Plate IV. 



Fig. 7.— Theoretical Arcs Formed in Air and in Vacuo 

 BY Deviable Rays. 



Fig. 8.— Dispersion of Deviable Rays in Magnetic Field. 



Fig. 9. —Impression Due to Secondary Rays. 



