who worked mostly in South Africa. He introduced the orbital parameters for double stars now known as Thiele–Innes constants in conjunction with the Danish astronomer Thorvald Nicolai Thiele (1838–1910). Innes measured stellar proper motions, and introduced the blink comparator, which he used in 1915 to discover Proxima Centauri. His Southern Double Star Catalogue (1927) included over 1600 doubles he discovered.