rotation, it implied that observations of other objects would be similarly affected. This was partially verified by observations of transits of Mercury, but Brown was initially not convinced. However, he eventually concluded that Newcomb was right, and not only was the Earth's rate of rotation slowing, but also there were random, unpredictable fluctuations, and he published these findings in a paper in 1926. Later work has shown this to be true, and astronomers now make a distinction between Universal Time, which is based on the Earth's rotation, and Terrestrial Time (formerly Ephemeris time), which is a uniform measure of the passage of time (see also ΔT). Later work and collaborations Brown was an active member of the American Mathematical Society and served as its president from 1915 to 1916. He retained his professorship at Yale until he retired in 1932. As well as continuing his work on the Moon, he also worked on the motion of the planets around the Sun. In 1933, he published the book, Planetary Theory, co-authored with Clarence Shook, which contained a detailed exposition of resonance in planetary orbits and examined the special case of the Trojan asteroids. In 1937, he was awarded the Watson Medal by the US National Academy of Sciences. One of Brown's post-graduate pupils was Wallace John Eckert, who became an instructor at Columbia University while finishing his doctorate. Eckert would improve the pace of astronomical calculations by automating them with digital computers. Private life Brown never married, and for most of his adult life lived with his unmarried younger sister, Mildred, who kept house for him. She made it her job to shield him from "cares and disturbances" and succeeded in "utterly spoiling him." In his youth, he was a keen rower and mountaineer. He was a capable pianist and continued to play until a few years before his death. He remained fond of music and was for a time the head of the New Haven Oratorio Society. Brown also played chess to a high standard and loved detective stories. He enjoyed travelling and frequently crossed the Atlantic between the United States and Great Britain. With several professional colleagues, he was also an enthusiastic participant in the British Association's extended visit to South Africa and other parts of southern and eastern Africa between July and October 1905. His daily routine was unusual, and was described as follows: He was in the