Astronomer. Born in Aberdeen, the son of a watch-maker, Gill was educated Dollar Academy followed by Marischal College (Aberdeen), where he was taught by James Clerk Maxwell (1831-79). Gill gained an interest in astronomy and was permitted to use the small telescope at King's College Observatory in 1862. In 1872, he was given responsibility for equipping a private observatory at Dunecht House belonging to James Ludovic Lindsay, the 26th Earl of Crawford (1847 - 1913).
Gill pioneered the use of photography to study the stars, taking thousands of plates of the sky between 1879 and 1907, giving rise to the concept of cataloguing stars using photographs. He is particularly noted for his classic photograph of the Great Comet of 1882. Gill also perfected an instrument to measure the angular separation of celestial bodies.
He served as Astronomer Royal for Scotland and was knighted in 1900 for his contribution to the field. He also organised geodetic surveys in Southern Africa.
Gill is remembered by a plaque on the wall outside his former home in Skene Terrace, Aberdeen.
