The first Observer
The idea of an observatory in Oxford was conceived by the then Savilian Professor of Astronomy, The Rev Thomas Hornsby, DD, who, in the age of the exploration of the South Seas, realised the importance of improved astronomical observation as a prerequisite for marine navigation. Hornsby persuaded the trustees of Dr John Radcliffe's estate to provide the funds and was appointed as the first Observer, a post which he occupied until his death in 1810.
When opened, the Observatory was equipped with the finest scientific instruments by the best makers of the day at a tremendous cost of £1,300, the equivalent of about £1m in today's money. Foremost among the makers was John Bird (1709-76) who spent the last years of his life making two 8-foot mural quadrants, a transit telescope, and a 12-foot zenith sector. These huge instruments were conveyed from London to Oxford by barge up the River Thames.
Reliable timekeepers were also essential for astronomical work, and high-quality clocks were provided, notably one by John Shelton. Although these instruments are no longer in the Observatory, many of them remain in Oxford and are to be seen in the Museum of the History of Science in Broad Street.
In addition to making astronomical observations, Hornsby and his successors kept meticulous meteorological records, compiled from consulting weather-recording instruments three times a day every day from 1774 until 1935. From 1881 onwards, the Observatory co-operated closely with the Meteorological Office, and for a long period before the First World War daily reports sent from Oxford by telegraph were included in the national Daily Weather Report.
Photographs of the Observatory before 1976 show an ungainly square room which was put on top of the Tower in Victorian times, but this disfigurement was removed in 1976-78 when Green College renovated the buildings. The original eighteenth-century furniture retained by the College includes an observers' chair, a telescope ladder, writing desks, chart chest, and a fine round table, once pictured in the library but now the centrepiece of the observing room.
In 1935, when the Observatory ceased to function as such, the site became the Radcliffe Meteorological Station, and observations continue to be made from instruments at ground level on the north lawn.
Adjacent to the main Observatory is the small observatory built to contain a heliometer made by Adolph Repsold of Hanover in 1849. The heliometer was removed in 1905 and is now in the Science Museum, London. The building has been restored as a reading-room and is now referred to as the Rotunda.
The Barclay Equatorial
This 10-inch refractor was built in 1860 by Thomas Cooke & sons of York for Mr Joseph Gurney Barclay FRAS of Leyton in Essex. The telescope was used by Barclay and professional astronomers from Europe (Hermann Romberg and Charles Talmage) until 1885 when it was given to the Radcliffe Observatory in Oxford. The Barclay Equatorial was used for double-star, comet and planetary work.
When the Radcliffe Trustees relocated the Observatory to South Africa in 1935, the Observer Dr Harold Knox-Shaw offered the telescope to Marlborough College. The Blackett Observatory opened shortly afterwards. Restoration and modernisation to motorise and electronically control the instrument was completed in recent years. Further information can be obtained from the Blackett Observatory.
The current Director of the Blackett Observatory is Mr Charles Barclay, a descendent of Mr Joseph Gurney Barclay.