(left to right) Robert Williams Wood (1868-1955), William Henry Bragg (1862-1942) and Charles Greeley Abbot (1872-1973), , Smithsonian Institution Archives, Robert Williams Wood (1868-1955) was professor of physics at Johns Hopkins University; Sir William Henry Bragg (1862-1942) was professor of physics at Cambridge University; and Charles Greeley Abbot (1872-1973) was Secretary of the Smithsonian Institution. They are shown at the NAS Spring 1939 meeting in Washington..