Astronomer. He served as the English Astronomer Royal and the director of the Royal Greenwich Observatory from 1910 to 1933. He is probably best remembered for introducing the Greenwich Time Signal in 1924, commonly referred to as "time pips" which were a broadcast of six one-second tones from Greenwich, England to British Broadcasting Corporation radio stations that marked the precise start of each hour. He was also an authority on the spectrum of the Sun's corona and chromospheres based on his study of solar eclipses. After attending Heath Grammar School in Halifax, England he won scholarships to Bradford Grammar School and Trinity College, Cambridge, where he studied mathematics and astronomy, graduating in 1889. He was elected a fellow of the Royal Society in 1901. From 1905 to 1910 he served as Astronomer Royal of Scotland prior to being appointed to the English Astronomer Royal position. During his tenure as the English Astronomer Royal, he played an important role in testing Albert Einstein's theory of general relativity through the observation of the 1919 solar eclipse in Brazil and Principe. These observations confirmed Einstein's theory of the effect of gravity on light. In 1928 he introduced a new free-pendulum clock in the Greenwich Observatory. After being knighted in 1915 for his achievements in the field of astronomy, he was awarded the Royal Medal of the Royal Society (1921), Bruce Medal (1922), Gold Medal of the Royal Astronomical Society (1925), and Knight Commander of the Order of the British Empire (1926). He died while traveling on board a ship from Australia to England and was buried as sea. The Dyson crater on the Moon and the asteroid 1241 Dysona are named in his honor.