The physicists most qualified to effect measurements in these delicate optical questions--M.

Cornu, Mr Preston, M.Cotton, MM.

Becquerel and Deslandres, M.Broca, Professor Michelson, and others--have pointed out some remarkable peculiarities.

Thus in some cases the number of the component rays dissociated by the magnetic field may be very considerable.
The great modification brought to a radiation by the Zeeman effect may, besides, combine itself with other phenomena, and alter the light in a still more complicated manner.

A pencil of polarized light, as demonstrated by Signori Macaluzo and Corbino, undergoes, in a magnetic field, modifications with regard to absorption and speed of propagation.
Some ingenious researches by M.Becquerel and M.Cotton have perfectly elucidated all these complications from an experimental point of view.
It would not be impossible to link together all these phenomena without adopting the electronic hypothesis, by preserving the old optical equations as modified by the terms relating to the action of the magnetic field.