Nobel Prize–winning physicist (1868–1953) who was the first to isolate the electron and measure its charge. TLS signed “R. A. Millikan,” one page, 8.5 x 11, California Institute of Technology letterhead, June 3, 1930. Letter to future New York Congressman Seymour Halpern. In part: “If I have had what you call success, which is a matter of considerable doubt, I don’t think I have the ability to analyze usefully the causes. Some of them have undoubtedly been, as it is the case with all of us, entirely outside of my control. If there were any of them which are due to my own qualities I presume they are the result largely of pretty intense and prolonged application, a habit which I learned early in youth.” Central vertical and horizontal folds, light scattered creases to the lower half of the sheet, a paperclip impression to the upper left, and a couple small dings and tears to the edges, otherwise fine condition. Halpern’s obituary in the New York Times mentions his “extensive collection of autographs.” RR Auction COA.