J. J. Thomson, by a rotating-mirror method, succeeded in measuring the velocity of the cathode rays, finding it to be 1.9 x 10 7 cm./sec.; a value so much smaller than that of the velocity of light that it was scarcely possible to conceive of the rays as vibrations of the aether.
If, in the very intense electric field in the neighbourhood of the cathode, the molecules of the gas are dissociated and are split up, not into the ordinary chemical atoms, but into these primordial atoms, which we shall for brevity call corpuscles; and if these corpuscles are charged with electricity and projected from the cathode by the electric field, they would behave exactly like the cathode rays.j. j. thomson
Thomson's lecture drew from Fitz Gerald the suggestion that "we are dealing with free electrons in these cathode rays" a remark the point of which will become more evident when we come to consider the direction in which the Maxwellian theory was being developed at this time.j. j. thomson
As the cathode rays carry a charge of negative electricity, are deflected by an electrostatic force as if they were negatively electrified, and are acted on by a magnetic force in just the way in which this force would act on a negatively electrified body moving along the path of these rays, I can see no escape from the conclusion that they are charges of negative electricity carried by particles of matter.j. j. thomson