Francis W. Aston was an English chemist and physicist whose motto--"Make more, more, and yet more measurements"--summed up the hard work and dedication he brought to a lifetime of achievement. Among his most important contributions were detailed observations of atomic phenomena with a mass spectrograph that he built himself. This device allowed him to articulate the theory that the atomic weight of each element is a whole number, but that most elements have isotopes (atoms of the same element with the same number of protons in their nucleus, but different numbers of neutrons). For these insights he received the 1922 Nobel Prize in chemistry. From evidence he gathered in the 1920s, Aston went on to note that the weights of atoms vary minutely from whole numbers in proportion to the density of their nuclei.

Francis William Aston was born on September 1, 1877, in Harborne, Birmingham, England, the third...