Jubilee of the Electron

Abstract

APRIL 30 marked the fiftieth anniversary of the announcement by J. J. Thomson, at an evening discourse at the Royal Institution ; of the existence of the electron, and the first approximate estimate of its mass. Cathode rays had been extensively studied in many laboratories for the previous fifteen or twenty years, and their peculiar properties had been widely discussed. It was Thomson's genius which enabled him to unravel the confusing and almost contradictory clues which the experiments afforded as to the nature of the phenomenon, to grasp what was important and what was secondary in the evidence, and to make the final experiment which demonstrated beyond all reasonable doubt that the cathode rays consisted of negatively charged particles, all alike, and all much smaller than the smallest particle hitherto known to science, the atom of hydrogen. The Institute of Physics and the Physical Society, in collaboration with the Institution of Electrical Engineers, is arranging to mark this jubilee by a series of lectures and other functions in London on September 25-26 next ; an exhibition demonstrating the great influence this discovery in pure physics has had on the life of the community will be opened at the Science Museum, London, on September 26 and will remain open for about three months.