"The absence of reflection, refraction, or polarization in the penetrating rays from uranium necessarily follows in the light of our present knowledge of the rays. It is now known that the uranium rays, mainly responsible for the photographic action, are deviable by a magnetic field, and are similar in all respects to cathode rays, i.e. the rays are composed of small particles projected at great velocities. The absence of the ordinary properties of transverse light waves is thus to be expected."