Reprinted in Philosophical Magazine and Journal of Science, London, Edinburgh, and Dublin ser. 5, v. 44, n. 269 293.
Proceedings of the Royal Institution, 15 (1897) 419.
Great Experiments in Physics ed. by M. H. Shamos, Henry Holt and Company, New York (1960).
The WORLD of the ATOM, editors H. A. Boorse and L. Motz, Basic Books, New York - London, V.I (1966) 416.
The experiments discussed in this paper were undertaken in the hope of gaining some information as to the nature of the Cathode Rays. The most diverse opinions are held as to these rays; according to the almost unanimous opinion of German physicists they are due to some process in the aether to which-inasmuch as in a uniform magnetic field their course is circular and not rectilinear-no phenomenon hitherto observed is analogous: another view of these rays is that, so far from being wholly
aetherial, they are in fact wholly material, and that they mark the paths of particles of matter charged with negative electricity. It would seem at first sight that it ought not to be difficult to discriminate between views so different, yet experience shows that this is not the case, as amongst the physicists who have most deeply studied the subject can be found supporters of either theory. The electrified-particle theory has for purposes of research a great advantage over the aetherial
theory, since it is definite and its consequences can be predicted; with the aetherial theory it is impossible to predict what will happen under any given circumstances, as on this theory we are dealing with hitherto unobserved phenomena in the aether, of whose laws we are ignorant. (Extracted from the introductory part of the paper.).
Discovery of the electron, the first elementary particle.