The Shepherd Gate Clock

Located at the entrance to the Royal Observatory, the Shepherd Gate Clock is more than a fascinating historic object. It tells the story of how Greenwich became the centre of the world's time system.

What is the Shepherd Gate Clock?

The Shepherd Gate Clock is a historic public clock at the Royal Observatory Greenwich. It was installed in 1852 and became the first clock to display Greenwich Mean Time directly to the public.

Unlike a conventional clock, which completes two 12-hour cycles each day, the Shepherd Gate Clock uses a 24-hour dial. Its unusual design reflects the Observatory's role in measuring, maintaining and distributing accurate time.

The clock is named after Charles Shepherd, the clockmaker whose electrical timekeeping system helped transform the way people kept time.

Before standardised time became widespread, towns and cities often kept their own local time, based on the position of the Sun. This meant that the time could differ from one place to another.

The development of the railway made these differences increasingly difficult to manage. A shared time system was needed to help coordinate railway timetables, communications and everyday life.

The Shepherd Gate Clock became a visible symbol of this transformation. By displaying Greenwich Mean Time, it helped demonstrate how a single, accurate time standard could be used across the country.

The clock is an important part of the story of how Greenwich Mean Time became a national and eventually international standard.

One of the most distinctive features of the Shepherd Gate Clock is its 24-hour face.

Most clocks divide the day into two 12-hour periods. The Shepherd Gate Clock instead shows all 24 hours of the day on a single dial.

This means that:

• Midnight is shown at the top of the dial
• 6am is shown on the right-hand side
• Noon is shown at the bottom
• 6pm is shown on the left-hand side

The position of the hour hand makes it easy to distinguish morning from afternoon.

At noon, the hour hand points directly downwards, rather than upwards as it would on a conventional 12-hour clock.

This unusual design makes the Shepherd Gate Clock one of the most recognisable historic clocks at the Royal Observatory.

How does the Shepherd Gate Clock work?

The Shepherd Gate Clock is a sympathetic clock. This means that it does not independently keep time in the same way as a conventional clock.

Instead, it receives electrical impulses from a highly accurate master clock inside the Royal Observatory, known as the motor clock.

The motor clock regulates the time, while the Shepherd Gate Clock displays it to the public.

This system allowed multiple clocks to remain synchronised with a single source of accurate time.

The technology was a major development in the history of timekeeping, helping to make precise time available to people over much greater distances.

The influence of Greenwich time extended beyond Britain.

In 1866, time signals were transmitted from Greenwich to Harvard University in Massachusetts using the new transatlantic submarine telegraph cable.

This development helped establish an international network for distributing accurate time.

It demonstrated that timekeeping could be coordinated across continents, laying important foundations for the global systems of communication and navigation that followed.

The Shepherd Gate Clock takes its name from Charles Shepherd, a clockmaker based in Leadenhall Street, London.

In 1851, Shepherd installed one of the world's early electric clock systems at the Great Exhibition in Hyde Park.

The system consisted of a central motor clock that sent electrical impulses to a number of connected clocks, known as sympathetic clocks.

George Airy, the seventh Astronomer Royal, recognised the potential of the technology and commissioned a system for the Royal Observatory Greenwich.

The Shepherd system was supplied to the Observatory in 1852 and remained the basis of Britain's time-distribution system for approximately 70 years.