Physicist Robert Millikan determined through an oil-drop experiment the value of the charge on an electron. He then demonstrated that the charge was a discrete constant rather than a statistical average. For his work, as well as for work on the photoelectric effect, Millikan received the Nobel Prize for physics in 1923. He spent 25 years at the University of Chicago and 32 years at the California Institute of Technology. His "First Course in Physics," written with Henry Gale, was a standard textbook for many years.