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Nebulae sweep book of William Herschel

Reference number: MS/272/7

Date: 26 March 1789-30 September 1802


Records of telescopic sweeps of the night sky, made at Slough, Berkshire, England, generally with a reflecting telescope of 20 feet diameter. The sweeps were made to observe nebulae, with notes on stars and other objects of interest. There are occasional meteorological observations. The volume contains astronomical sweeps numbered 918-1112, with the dates, times and positions of each observation. Several sweeps might be undertaken in one night of observation. Herschel provides a commentary on many objects, more detailed in the case of interesting nebulae. Additional observations include comments on his equipment and its impact on the quality of the observations.

This volume contains far less general matter, with no records of visitors or observations of other astronomical objects such as planets. Herschel notes errors, including a memorandum on 1 October 1790, 'In the three last sweeps we found it impossible to make any of the stars to agree with given Catalogues, and now had reason to think the time piece disordered...' A sewn-in paper slip correction appears at 11 May 1801. The observations conclude with 'New 20 ft. mirror. The stars are very distinct'.

The front cover is inscribed in ink: '(Originals) Sweeps No.7. 918......1112. From March 26, 1789 To Sep. 30, 1802.'

Reference number
Earliest possible date
26 March 1789-30 September 1802
Physical description
On paper, sewn into a pasteboard cover, with a second paper cover sewn over that.
Page extent
190 pages. [pp.1-116 used, the remainder blank]

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Nebulae sweep book of William Herschel, 26 March 1789-30 September 1802, MS/272/7, The Royal Society Archives, London,, accessed on 17 June 2024

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