Aston, Francis William (1877-1945), was an English physicist. In 1919, he invented the mass spectrograph, which made possible the separation of atoms according to extremely small differences in their masses. Using this instrument, Aston proved that almost all elements are composed of mixtures of various isotopes, sharing the same atomic number but differing in nuclear mass (see Isotope ). Aston received the 1922 Nobel Prize in chemistry for this research. He was born on Sept. 1, 1877, in Birmingham, England. Aston studied at Cambridge University. From 1910 until his death on Nov. 20, 1945, he did research at Trinity College, Cambridge.
