A project to restore a time ball on top of the Nelson Monument in Scotland has been awarded £50,000 by the Heritage Lottery Fund (HLF).

Work at the Calton Hill site will form part of the Twelve Monuments project, which aims to restore some of the city's most famous statues and monuments, including the Black Watch Monument. The conservation work will see the repair of the 762kg time ball's gearing mechanism, which has been out of operation for 18 months, as well as the replacement of worn cogs and supporting timber structure. The Nelson Monument will also undergo some stonework repair.

Installed in 1852 by Charles Piazzi Smyth, second Astronomer Royal of Scotland, the time ball was originally designed to allow ships' captains in Leith docks to set chronometers accurately by observing the dropping of the ball at one o'clock each day. The one o'clock gun was added in 1861 at Edinburgh Castle to provide an audible signal. The project is expected to take six months to complete, and will cost around £230,000. Further fundraising is continuing, and it is hoped work can start in the New Year.

Edinburgh World Heritage (EWH), in partnership with the City of Edinburgh Council, is leading the project, with support from the One O'Clock Gun Association and the Friends of Hillside and Calton Area Association. Director of EWH, Adam Wilkinson, said: "This important project is part of the wider restoration of the monuments and statues in the World Heritage Site. The time ball is one of the idiosyncratic rituals and living history which are part of the life of the city."

Head of the HLF in Scotland, Colin McLean, said: "The time ball is enjoyed by local people as well as tourists from all over the world."