ROBERT STAWELL BALL was born in Dublin on July 1, 1840, the eldest son of Dr. Robert Ball, director of the Natural History Museum in the University of Dublin and secretary of the Queen's University in Ireland. After attending school at Abbott's Grange, Chester, he entered Trinity College, Dublin, in 1857. He became a mathematical scholar in 1860, Lloyd exhibitioner the same year, and graduated in 1861 as gold medallist in mathematics, first gold medallist in experimental and natural sciences and University student in mathematics. To-wards the end of 1865 he went to Parsonstown as tutor to the three younger sons of the third Earl of Rosse and observer with the great six-foot and three-foot telescopes. When Ball began to use the six-foot reflector in February, 1866, nearly all the larger and more interesting nebulae had been frequently observed and carefully drawn, and he therefore chiefly devoted himself to work with the micrometer, a difficult task, since the telescope at that time had not yet been provided with a clock motion. He was the first observer with the instrument who corrected the measured position angles for the error due to the telescope not being equatorially mounted, but supported at the lower end on a universal joint. His observations were included in the “Observations of Nebulas, 1848–78,” published by the late Lord Rosse in 1879–80.