Nebulae sweep book of William Herschel

Description

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 453-609, 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.

Herschel also observes the planet Mars on 1-2 December 1785, attempting to measure it with a micrometer and Jupiter, and noting that 'The belts of Jupiter were visibly incurvated...' He sketches 'The Georgium Sidus' [Uranus] on 7 December with stars which he concludes were not satellites. He conducts experiments with a polar distance clock from 29 January 1786 and makes an improvement to the bell machine on 31 January. The section for 2 March 1786 commences with a trial for sweeping in the zenith. On 4 May 1786 he sees 'Mercury on the dish of the Sun', eg a transit of Mercury, and attempts micrometer measurements. He views his sister's [Caroline Herschel's] comet using a 7-foot reflecting telescope on 19 August 1786, sketching its position relative to a star and nebula and again on 20 and 23 August. Visitors included Henry Cavendish, Charles Blagden and Sir Joseph Banks on 22 April 1786: 'A Nebula. Sr. J. Banks. He perceived it in the field just when my Sister said there it is'. Later, 'Lord Efffingham, another gentleman and Mr Arnold' who view a nebula on 3 June 1786.

The inside front cover contains a long key to abbreviations used. The rear inside cover has a brief note commencing 'HF=30" of time in the Equator...'.

The front cover is inscribed in ink: '(Originals) Sweeps. No.5. 453...609. From October 4, 1785. To October...13, 1786.'

Reference number

MS/272/5

Earliest possible date

4 October 1785-13 October 1786

Physical description

On paper, sewn into a pasteboard cover.

Page extent

196 pages.

Format

Manuscript