Regulator clock, Charles Frodsham, London, 1865

The Frodsham Regulator was the most important of the scientific clocks used by the Melbourne Observatory in the 19th century. Purchased in 1865, it was linked to telescopes to map the southern hemisphere stars, set Standard Time for Victoria, and establish more precise measurements of Melbourne's longitude. It was an integral part of the first major international project to map the stars of the southern hemisphere.

This was a collaborative project with the observatories at Cape of Good Hope and Madras, and coordinated by the Royal Observatory at Greenwich. The clock was located in the Library and linked electrically to the Second Transit Instrument in the Second Transit Room. By 1871 Government Astronomer Robert Ellery and his second assistant C Moerlin had observed the positions of nearly 50,000 stars.

When Ellery visited Britain in 1875, the Astronomer Royal, George Airy, praised Ellery's work, stating publicly that the Melbourne Observatory had published the best catalogue of stars of of the Southern Hemisphere. In 1883 the Frodsham No 1062 was moved to the new East Transit Room, and connected to the recently installed 8-inch Transit Telescope recently purchased from the London firm of Troughton & Simms.

In conjunction with the 8 inch transit telescope and one or two other clocks, the Frodsham No 1062 was used to set Standard Time for the Colony of Victoria. The Frodsham was also involved in fixing the longitude of Melbourne.

Recently established telegraphic connections with Greenwich Observatory, via the Overland Telegraph, Darwin and underwater cable, enabled the Observatory in 1883 to undertake a more accurate fixing of Melbourne Observatory's longitude. The clock was transferred to Mt Stromlo Observatory in 1944, along with the 8-inch transit telescope.

The telescope was subsequently sent to Greenwich Observatory, then returned to Melbourne in the 1970s, and is now held in the Museum's collection. The clock was prevented from being exported under the Commonwealth Government's Protection of Moveable Cultural Heritage legislation.