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Blackett Observatory Dome
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(Article submitted to Astronomy Now magazine by C.E. Barclay FRAS and published in February 2003)

The Restoration and modernisation of an antique telescope.

In 1860 Joseph Guerney Barclay F.R.A.S aged 44 ordered a 10-inch refractor telescope with a 12-foot focal length from Thomas Cooke in York. It was to be made to a high standard with vernier scales in silver. The telescope was installed at his house in Leyton, Essex and with the assistance of professional Astronomers from Europe, Herman Romberg (a pupil of Encke) and C.G. Talmage, Barclay observed and recorded adding to W Struve’s catalogue of Double Stars, publishing data on the prominent comets of 1860 and 1862 and also working on the motions of Jupiter’s satellites and the fainter planets. Romberg only stayed for 2 years and Talmage a little longer, but by 1870 it appears that the Telescope was little used, possibly due to Barclay’s inability to fill the Observers post. In 1885 he was approached by the Radcliffe Observer Edward Stone. The Racliffe Observatory in Oxford was struggling and badly in need of a decent instrument with which to begin competition with the ever better equipped observatory in Cambridge. Mr Barclay gave his telescope to the Radcliffe that year.

In 1997 I applied for the post of Head of Physics (with an interest in Astronomy) at Marlborough College in Wiltshire. Having an Astronomy degree from St Andrews University it was a natural step from teaching in the Physics Department at Westminster School, London. At interview I was shown an old telescope in a small but well sited dome. The scope was in poor condition with many layers of paint even over moving parts, unreadable scales, a broken motor drive and scrunched gear wheel teeth on the RA drive wheel. The tube was damaged and additional holes had even been drilled to attach a makeshift rig to hold a camera. The Telescope however looked significant and the T. Cooke and Sons 1860 plate was promising. I was offered the job and within a few months of starting decided to restore and re-motorise the instrument, with no blue prints to hand nor any knowledge of its history, save that it had been donated by Oxford in 1935.

The first problem was how to re-motorise, given the damaged drive wheel. After much searching, a company AWR engineering in Deal suggested a Mr Norman Walker (ex RGO) from Sussex. The project commenced full of unknowns in January 1997. As the telescope came apart the skill of its manufacture became obvious, machining was perfect and joints moved smoothly with no bearings. As layers of paint were removed, the original brass and silver were revealed casting doubt on the University as the first owner. With a unique design for a new RA drive, the possibility of a Dec. drive as well to enable eventual computer control was considered. With designs being handed to an ex-naval engineering firm TransDev in Poole, Dorset, who unusually were able to tackle machining of 3-foot diameter brass to less than a thousandth of an inch precision, the jobs had to be slotted into a busy 21st century work schedule.

The provenance of the telescope needed to be investigated and the original owner quickly emerged. The Radcliffe used the 'Barclay Equatorial' from 1885 till 1930 continuing Barclays work and also observing the motions of stars within clusters. In August 1885 one of the first light curves of the fading super nova in Andromeda was recorded. This was a critical piece of evidence in the theory of nucleo-synthesis proposed in 1955. When the observatory was relocated to South Africa, Dr Harold Knox-Shaw, the last Oxford based Radcliffe Observer sought to find homes for the instruments. The 24/18-inch double refractor went to The University of London at Mill Hill and in 1935 he offered the 10 inch to Marlborough College, Wiltshire. Following the set up of a telescope fund, old boys of the College raised some £800 required to move the instrument and re-house it in a dome acquired from a private observatory in Torquay. The Observatory was opened in 1935 by Knox-Shaw and named the Blackett observatory after Sir Basil Blackett, old boy and head of the telescope fund who died earlier that year. Joseph Guerney Barclay was my great grandfather's first cousin and suddenly by some quirk of coincidence I was overseeing the restoration not only of an antique with a significant role in the development of Astronomy in Oxford but also a close personal connection.

By 2001 the telescope was reassembled but the motor torque required for the tonne or so of telescope was causing problems. After a period of re-gearing and the purchase of a more powerful motor, the instrument moved under electronic control specifically designed by AWR in March 2002. Due to the addition of the extra Dec. drive wheel, the telescope was now significantly unbalanced and though so close to finishing, the 300-weight solid iron counter -weight had to be slimmed. By July 2002 the scope could be used and at last the quality of the lens could be seen. The brass eyepiece end had been modified to take Meade equipment and so lenses, photographic filter assembly and CCD could be attached. With a fibre optic connection, computer images will eventually be fed to the College network and with Solar and H-alpha filters, use will be extended into daylight hours. Once the scaffolding was removed in July, Sir Patrick Moore visited and put his seal of approval on the work carried out. On 11th October an august body assembled for an official opening. To have The Savilian Professor of Astronomy whose post spans many centuries of astronomical, together with representatives of the College and potential users from local schools and societies, gave a fitting accolade to the rising from the ashes of an important UK telescope.

The rescue of an antique has been a voyage of discovery and inspiration in itself and the telescope will hopefully now provide a further century of educational use.