American physicist who determined the charge on an electron using charged oil drop experiments in 1909. A scrutiny of his notebook, however, shows that he only selected "good" oil drops to publish, making notes such as "Beauty--Publish" and "One of the best I've ever had--Publish." In 1916, Millikan experimentally verified Einstein's predictions on the photoelectric effect, measuring the value of Planck's constant (h) in the process.