| 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. The volume contains astronomical sweeps numbered 46-141, with the dates and times of each observation. Several sweeps might be undertaken in one night, for example on 19 December 1783, Herschel notes sweeps numbered 52-59 timing them at between 5hrs 20 minutes to 16hrs 42 minutes. Herschel provides a description or commentary on many objects and the volume contains occasional sketches of views through the telescope.
A note on the inside front cover states that: ' Before these Sweeps in the meridian were made, I had made 45 in the parallel. See Journal. Those 45 were made by swinging the suspended telescope backwards and forwards. See page 450 fixt stars. The stroke with a pen drawn through the sweeps in this book only denote that the observations were transcribed into the journal generally the very morning after they were made. The first 15 sweeps were made by mean time, the 62 sweeps sidereeal time was used. L=large stars. S=small stars'.
The volume contains a loosely inserted and stab-sewn gathering of later sweep data, one item dated 15 January 1801, the remainder January or February.
The front cover is inscribed in ink: 'Sweeps. No.1. 46...141. From December 18, 1783. To February 13, 1784'. With a faint pencil inscription 'Herschel M.SS. Sweeps'. |