Nebulae sweep book of William Herschel

Description

Records of telescopic sweeps of the night sky, made at Slough, Berkshire, England, generally with reflecting telescopes of 10 and 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 351-452, 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 little general matter, with no records of visitors.

Herschel notes on 13 February 1785, 'I saw Venus with a new 10 feet reflector, but could perceive no kind of spot upon her. I examined the dark part of the Moon and had light enough to perveice several of the spots; but saw nothing luminous [...] Sw the Georgium Sidus with 240, the planetary disk perfectly visible and with some attention compleatly (sic) well defined, with the strongest of the double eye pieces, the disk also visible and well defined, this piece has a good effect and will please the dilettanti'.

The front cover is inscribed in ink: '(Originals) Sweeps No.4. 351......452. From January 6, 1785 To October 3, 1785.'

Reference number

MS/272/4

Earliest possible date

6 January 1785 - 3 October 1785

Physical description

On paper, sewn into a pasteboard cover.

Page extent

194 p. [inscriptions in the inside and back cover, no blank page]

Format

Manuscript