861 
Ronreen-effect, by eliminating the latter. This might be done in the 
following way: 
Take a sphere of insulating material, which is mounted to perform 
rotatory oscillations round a vertical axis. Surround its equator by 
a circuit fixed in space. Apply an electric field of constant horizontal 
direction, and the oscillations of the sphere must induce an oscilla- 
ting current in the circuit. 
The effect will be small, but it should be detectable with the aid 
of the modern detectors of radiotelegraphy. It will be proportional 
to the square of the electric field applied. 
It might be pointed out that a comparison of the effect with the 
produced polarization, would provide us with means to determine 
the number of electrons per atom, which are involved in the pola- 
rization, because, for a given polarization, the displacement 8 of the 
electrons is inversely proportional to the number ” of displaced 
electrons per atom, and so the effect of k per electron is inversely 
to n°. Materials with the same di-electric constant should show the 
effect to a degree inversely proportional to the number of polarizing 
electrons per atom. 
Spontaneous Electric Polarization of Moving Magnets. 
12. Though we have used in the title of this paper tne deno- 
minations “Polarization and Magnetization Electrons’, yet it is well 
known that it is impossible to make a rigorous distinction between 
the two. For even though there may be in some cases electrons 
which only produce polarization and no magnetization, there can 
be no electron which gives rise to a magnetization and never 
produces polarization. 
In fact, whenever magnetized matter moves in a direction per- 
pendicular to the magnetization, then it shows a polarization at right 
angles both to magnetization and motion. 
The explanation runs as follows. A magnetic atom contains elec- 
trons sweeping round the nueleus, in circles, say, with uniform 
velocity, under the actions of electromagnetic forces. When the atom 
acquires a motion in the plane of the circling electrons, then the 
forces are modified in a way given by the theory of electrons and 
of relativity. The effect of this alteration of the forces will be that 
the orbit is no longer a circle, and becomes an ellipse, and that 
the velocity changes in such a way that the electrons during a 
longer time stay in one part of the ellipse near an end of the long 
axis than in the other. This clearly results into a polarization. 
