ELECTRON  , the name suggested by Dr G .

Johnstone Stoney in 1891 for the natural unit of electricity to which he had drawn attention in 1874, and subsequently applied to the ultra-atomic particles carrying negative charges of electricity, of which Professor Sir J . J . Thomson proved in 1897 that the cathode rays consisted . The electrons, which Thomson at first called corpuscles, are point charges of negative electricity, their inertia showing them to have a mass equal to about 2 that of the hydrogen atom . They are apparently derivable from all kinds of matter, and are believed to be components at any rate of the chemical atom . The electronic theory of the chemical atom supposes, in fact, that atoms are congeries of electrons in rapid orbital motion . The size of the electron is to that of an atom roughly in the ratio of a pin's head to the dome of St Paul's cathedral . The electron is always associated with the unit charge of negative electricity, and it has been suggested that its inertia is wholly electrical . For further details see the articles on ELECTRICITY; MAGNETISM; MATTER; RADIO-ACTIVITY; CONDUCTION, ELECTRIC; The Electron Theory, E . Fournier d'Albe (London, 1907); and the original papers of Dr G . Johnstone Stoney, Proc .

Brit .

Ass . (Belfast, August 1874), " On the Physical Units of Nature," and Trans . Royal Dublin Society (1891), 4, p . 583 .