Nelson Monument - time ball removed for conservation

One of the most challenging operations in the restoration of the Nelson Monument has been successfully completed – the removal of the time ball and its mechanism. 

The time ball and its supporting mast were carefully craned off the top of the monument on 22 April and transported for repair at the workshops of Charles Laing & Sons.

The repair work is part of the Twelve Monuments Restoration Project, a joint initiative between Edinburgh World Heritage and the City of Edinburgh Council.

The time ball was designed by Maudsley Field & Sons, and installed in 1852. Its purpose was to enable ships’ captains to set their chronometers accurately, by observing the dropping of the ball at one o’clock Greenwich Mean Time each day.

It was originally linked to a master clock in the City Observatory and later in 1861 the One O’clock Gun at Edinburgh Castle was added to give an audible signal as well.

The time ball itself consists of a timber ball sheathed in zinc, which rises and falls around a central timber post. The timber central post which guides the ball during each operation is crowned with a cast iron hub, to which are fixed four timber directional arms, and a flag pole.

The timber structure has survived surprisingly well over the years but with the stress of its daily impact with its rest point at the base of the guide post, it has begun to crack. This in turn has placed further stress on the zinc covering, and sections have now begun to break away.

The ball’s zinc covering will be removed to expose the damaged timber. This will be replaced as required and treated against further decay. The zinc covering will have the dents and fractures removed and new sections pieced in place, before being re-wrapped around the timber ball and resealed using silver solder welding.

The operating mechanism for time ball is also being restored. Each section is being dismantled and cleaned prior to reinstallation. A new gear wheel is also being cast and installed to replace the original, after 150 years of use. All the repairs will be completed using traditional methods and removing the minimum necessary amount of damaged material.

The Twelve Monuments Restoration Project is supported by:
Heritage Lottery Fund, J.Paul Getty Foundation, the Wolfson Foundation, the Marquess of Bute, Babcock Marine, the Pilgrim Trust, The Binks Trust and others.