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Thomson's Electron and e/m

It was found that negatively charged particles called "cathode rays" could be coaxed out of a hot metal filament by a large enough electric potential and accelerated to hit a screen covered with phosphorescent material where they made a bright spot [the forerunner of today's cathod ray tubes or CRT's], but until 1897 no one knew much about the properties of these particles. In that year Joseph John Thomson used magnetic deflection (the LORENTZ FORCE) to determine the charge-to-mass ratio   q/m  of the cathode rays.^23.3 He found an astonishingly large negative ratio:   q/m = -1.76 x 10¹¹  coulombs/kg, indicating that the ELECTRON (as the "cathode ray" particle soon came to be known) must be a very light particle (mass m_e) with a very large electric charge (q = -e) where the "electronic charge"  e  was thought until recently to be the QUANTUM of electric charge - i.e. the irreducible minimum nonzero quantity of electric charge, in integer multiples of which all larger charges must come.^23.4