SIR ROBERT S. BALLSir Robert Stawell Ball FRS was an Irish astronomer who developed the screw hypothesis. He died on November 25, 1913. At Dunsink Observatory, he was the Royal Astronomer of Ireland. His parents were naturalist Robert Ball and Amelia Gresley Hellicar.He was brought up in the Irish town of Dublin. He was educated at Trinity College Dublin, where he was a senior moderator in both mathematics and experimental and natural science in 1861. From 1865 until 1867, Ball served for Lord Rosse. He was appointed Professor of Applied Mathematical Sciences at the Royal Irish College of Science in Dublin in 1867. He lectured on mechanics and wrote an introductory overview of the science there. He was elected to be a Fellow member of the Royal Society in 1873. He was named Royal Astronomer of Ireland and Andrews Professor of Astronomy at Trinity College Dublin's Dunsink Observatory in 1874. By delineating the screw displacement, Ball contributed to the science of kinematics: When Ball and the screw theorists speak of screws, they no longer mean actual cylindrical objects with helical threads cut into them, but the possible motion of anybody whatsoever, including that of the screw independently of the nut. Read More Read Less