EUGEN GOLDSTEIN

In 1886 Eugen Goldstein noted that cathode-ray tubes with a perforated cathode emit a glow from the end of the tube near the cathode. Goldstein concluded that in addition to the electrons, or cathode rays, that travel from the negatively charged cathode toward the positively charged anode, there is another ray that travels in the opposite direction, from the anode toward the cathode. Because these rays pass through the holes, or channels, in the cathode, Goldstein called them canal rays.

When the cathode of a cathode-ray tube was perforated, Goldstein observed rays he called "canal rays," which passed through the holes, or channels, in the cathode to strike the glass walls of the tube at the end near the cathode.  Since these canal rays travel in the opposite direction from the cathode rays, they must carry the opposite charge.