The Perth Observatory Calver

Perth Observatory 12.5-inch Calver – Perth Observatory Archives

The purchase of the Perth Observatory's Calver 12.5-inch* Newtonian reflector, manufactured by George Calver & Co. England, was approved in 1910 by the WA Government with a view for use during Comet Halley^[1], and as the Observatory’s first dedicated visitor telescope; its estimated cost was to be £300.

Unfortunately, it did not arrive in Western Australia until July 1911.

Its installation was delayed not only by the WA Government Public Works Departments inability to deliver a concrete pad or building in time for Comet Halley, but also mechanical issues with the telescope itself.

The problems with the telescope were conveyed to the instrument’s maker, George Calver (1834-1927), through numerous letters that still exist in the Perth Observatory archives^[2]. The Government Astronomer, William Ernest Cooke, investigated the issues personally and discovered that the mount had been jolted in transit, affecting the adjustment of the lower bearing of the polar axis. Once resolved, Cooke reported this to Calver who replied on 23 April 1911: “I am so thankful to get your letter of today, I am indeed pleased to hear it is in full swing and giving satisfaction.”

The telescope was later used in the 1922 Wallal total solar eclipse expedition, which famously provided key evidence supporting Einsteins Theory of Relativity that space was indeed curved; how it survived a beach landing in a long boat, as this was the only way to access the remote coastal site selected, one wonders.

In 1975, the Calver was loaned to the Astronomical Society of Western Australia (ASWA), with permission from the Chief Secretary’s Department. In the 1990s, the Observatory requested its return for restoration, and the telescope was brought back in 1996 to mark the Observatory’s Centenary.

Today, the Calver remains an active visitor telescope and can still be viewed and used during nighttime tours at the Perth Observatory in Bickley, Western Australia.

[1] Aspects of the History for the Perth Observatory, M.L. Clarke – Historical Note No. 5, Astronomical Society of Victoria, March 1987 p10.

[2] Perth Observatory Archives – File 07/23 – Instruments – Calver 12 ½" Telescope.

*32cm