ABSTRACT
Early researchers thought of electricity as a kind of fluid, leading to the inherited jargon such as current, flow, and valve. Fleming recognized the importance of Edison and Upton’s discovery and demonstrated it could be used for the rectification of alternating currents. Interestingly, Fleming, at first, tried to get reliable rectification from single-crystal rectifiers used in crystal set radios (Figure 1.2), but could never get them to work well enough, so he switched to tubes!
