William Crookes

The Discovery of the Electron (William Crookes)

The definitive experiments with cathode-ray tubes were done by William Crookes in 1879. Crookes' major contribution was the development of a better vacuum pump that allowed him to produce cathode-ray tubes with a smaller residual gas pressure. Crookes not only confirmed the previous work by Plucker, Hittorf, and others, he was able to show that cathode rays are negatively charged by studying the direction in which cathode rays are deflected by a magnetic field.