Becquerel:  from x-rays to phosphorescence to uranium

     What are these new rays?  Particles or EM

     Where do they come from?
          Chemical isolation
          New radioactive elements

     What is going on?
          What is the source of the energy?
          Messy chemistry:  more than one radioactive source
          The explanation:  transmutation (1902)
          Radioactive decay:  a statistical process

The nature of the cathode rays

     Aetherial disturbances or particles carrying charge?
          A troubled question in post-Maxwellian EM
          British and German hypotheses

     Work left to be done
          Theoretical:  Lorentz's EM field theory
          Experimental:  properties of the rays

     J.J. Thomson and the electron (1897)
          Thomson's background
          Cathode rays as particles carrying charge
          Measuring the properties of these particles
          What are these little pieces of matter?
          Ambiguous relations to Lorentzian electrons