Caroline Herschel's Comet Sweepers

Royal Astronomical Society Herschel MSS , W.4/1.3, p. 217.

His friend, Watson William Dr Jr , sent him the “Catalogue des Nebuleuses et des amas d'Étoiles” published by Messier in Connoissance des temps for 1783 (letter of Watson to Herschel, 7 December 1781; Herschel MSS, W.1/13.W.11).

Quoted in The Herschel chronicle, ed. by Lubbock Constance A. (Cambridge, 1933), 150.

Herschel MSS, W.4/1.3., p. 240.

Herschel MSS, W.4/1.4, pp. 333, 338, 344, 370.

Ibid., p. 338.

Herschel W. , “Catalogue of double stars”, Philosophical transactions, lxxii (1782), 112–62.

Herschel John Mrs , Memoirs and correspondence of Caroline Herschel (2nd edn, London, 1879), 53–54.

As we shall see, the sketch published by Smyth W. H. and said to be of this sweeper is in fact of its larger successor.

Herschel W. , “On the power of penetrating into space by telescopes”, Philosophical transactions, xc (1800), 49–85, p. 71. Caroline gives some details of the sweeper in her first Book of Observations (Herschel MSS, C.1/1.1, p. 11).

Herschel MSS, W.4/1.5, p. 447.

The “large” 20ft reflector was used for the first time on 23 October 1783, and the first trial ‘sweep’ for nebulae and clusters took place five nights later.

Quoted in The Herschel chronicle, ed. by Lubbock , 150.

Herschel John Mrs , Memoirs and correspondence of Caroline Herschel, 70–71, 80–89; The Herschel chronicle, ed. by Lubbock , 245–52.

See ref. 10. Caroline says it had a field of 1°48′ (Herschel MSS, C.1/1.1, p. 77), and a double eyeglass with an equilateral triangle of wires (C.1/1.4, back cover). Cf. Herschel W. , “Miscellaneous observations”, Philosophical transactions, lxxxii (1792), 23–27, p. 24.

Smyth W. H. , The Bedford catalogue (= vol. ii of his Cycle of celestial objects, London, 1844), 540; see our Appendix. In an article entitled “Caroline Herschel and her telescopes” (Arithmos-Arrythmos, Festschrift für Joachim Otto Fleckenstein, ed. by Figala Karin and Beminger Ernst H. (Minerva Publikation, Munich, 1979), 181–7), Hoskin wrote: “… It seemed much more likely that Smyth had … mistaken a sketch of the large sweeper … for one of the small one”, but felt compelled to accept John Herschel's statement that the sketch was of “the little sweeper” (p. 184). The documentary evidence that has since come to light and is presented in the present paper shows that Smyth had indeed misunderstood Herschel, by whose standards the large sweeper was ‘little’. The present paper incorporates material from Hoskin's previous article, which it supersedes.

Namely , Quarterly bulletin of the South African Library, xxv (1970), 16–17.

Pigott archives of the Royal Astronomical Society , Letter 60.

Herschel John Mrs , Memoirs and correspondence of Caroline Herschel, 93–95; The Herschel chronicle, ed. by Lubbock , 252–4.

Herschel MSS, C.1/1.3, pp. 100–11.

It seems more likely that it remained in Slough since, as we see in the Appendix, Smyth sent to John Herschel for approval a sketch of a stand for a comet sweeper that Smyth thought Herschel had shown him at Slough. In his reply, Herschel rejects the sketch but does not deny showing Smyth such a stand.

We owe this information and transcription to the kindness of Shorland Eileen Mrs (née Herschel).

Herschel at the Cape, ed. by Evans David S. (Austin, Texas, 1969), 46.

Herschel John Mrs , Memoirs and correspondence of Caroline Herschel, 305; he took the box with mirror in the morning and the stand in the evening. Caroline's 7ft reflector was packed up for shipment to England, 5 and 6 October 1839 (ibid., 304), and jointly presented to the RAS by John and Caroline (Monthly notices of the Royal Astronomical Society, v (1843), 79); it is now in the Science Museum, London. In a characteristic letter to John's wife written on 5 April 1840, Caroline says: “My sweeper, which I should have been so happy to put in the hands of my little grand-nephew, and teach him to catch comets till he could do something better (O! Why did I leave England!) is now in the hands of the good, honest creature, Director Hausmann, and the seven-foot telescope is also saved from being sold for an old song….” (Memoirs, 312). In one of her rare blunders, Clerke Agnes (The Herschels and modern astronomy (London, 1895), 125) says that Caroline presented the small sweeper to Hausmann and the large one to the RAS.

“Dear Sir John I am about to have a small illustration cut of the sweeper whose stand you shewed me in a corner of the grounds at Slough,—& my sketch—only made as a reminder—is so slight, that I am induced to ask for your revision,—but without taxing your time. The slightest description will suffice to point out the movements….” (Royal Society Herschel Papers, H.S. 16.274). Smyth had visited Herschel shortly before 6 May 1832 (ibid., 245).

The original is in the South African Library; see also ref. 17. In his reply to Herschel , dated 4 December 1843, Smyth writes: “In sending this I must thank you for your last letter, & the sketch of the comet-sweeper. Where could I have got that rickety sketch? I found it among my papers, & had a notion that I had seen something resembling it in the corner of your lawn. It is lucky I sent it for your inspection.” (Royal Society Herschel Papers, H.S. 16.275).

Ibid., 276.

We are grateful to Miss Mari Williams for helping in our search for this letter.