My small Newtonian sweeper—where is it now ?

Abstract

Caroline Lucretia Herschel, apart from being the amanuensis of her brother, Sir William Herschel, F.R.S., was herself a remarkable observer. In contrast to her brother, who was never the first to see a comet, she was not only the first woman to discover a comet, but found eight. Her success was due to an amazing familiarity with the sky. As can be read in a manuscript recently discovered in Hanover, she expected even an amateur to be able to recognize any star up to the 4th magnitude of brightness on sight, and to find any nebula in the ‘ Connaissance des Temps’ within a minute. What did the instruments that she used look like? This new discovery in Hanover makes it clear that Michael Hoskin and Brian Warner, in their article in the Journal for the Journal for the History of Astronomy (12 (1981), no. 1) did not identify correctly the instruments of which they published sketches (figures 1—3). In brief, Hoskin and Warner argued that figure 1 was a sketch of Caroline’s small comet sweeper, that figure 2 showed Caroline’s 5 ft sweeper, and that W. H. Smyth’s captions were simply wrong. The evidence from Hanover shows that figures 2 and 3 are Caroline’s ‘small Newtonian Sweeper’, which she was using in 1785 as Smyth says, and with which Caroline Herschel must have found what Fanny Burney called ‘the first lady’s comet’ on 2 August 1786(1).*