 Similar results had been found by George FitzGerald and Walter Kaufmann.Most of what was then known about electricity and magnetism, however, could be explained on the basis that charge is a continuous variable; in much the same way that many of the properties of light can be explained by treating it as a continuous wave rather than as a stream of photons.The beauty of the oil-drop experiment is that as well as allowing quite accurate determination of the fundamental unit of charge, Millikan's apparatus also provided a 'hands on' demonstration that charge is actually quantized.