* The author wishes to thank the Royal Society for permission to study and quote from the Herschel Papers, and Dr E. J. Bowen, Mr G. L'E. Turner, and Dr A. D. Orange for reading parts of this paper and offering much helpful advice.

¹ See Dingle, H., ‘A hundred years of spectroscopy’, The British journal for the history of science, 1 (1962–1963), 199–216CrossRefGoogle Scholar; also Roscoe, H. E., Six lectures on spectrum analysis (4th edn., London 1885), pp. 84–7.Google Scholar

² In addition to the studies cited in note 1, McGucken, W.'s Nineteenth century spectroscopy (London and Baltimore, 1969)Google Scholar gives an account of certain aspects of the subject in considerable detail.

³ Wollaston, W. H., ‘On a method of examining refractive and dispersive powers by prismatic reflection’, Philosophical transactions of the Royal Society, xcii (1802), 378–80.Google Scholar

⁴ Newton, I., Opticks (4th edn., London 1730; reprinted New York, 1952, by Dover Books), p. 72.Google Scholar

⁵ Melvill, T., ‘Observations on light and colours’, Edinburgh physical and literary essays, ii (1752), 35Google Scholar. For further comment on the development of the chemical flame test, see Szabadvary, F., History of analytical chemistry, trans. Svemla, G. (London, 1966), pp. 58, 186.Google Scholar

⁶ von Fraunhofer, J., ‘Bestimmung des Brechungs- und Farbenzerstreuungs- Vermögens verschneider Glasarten, in Bezug auf die Vervollkommung achromatischer Fernröhre’, Denkschriften der Kōniglichen Akademie der Wissenschaften zu München, v (1817), 193–266Google Scholar. Translated by Brewster, D. in Edinburgh philosophical journal, ix (1833), 288–99Google Scholar; also translated in Ames, J. S. (ed.), Harper's scientific memoirs, no. 2 (London and New York, 1898), pp. 3–10.Google Scholar

⁷ Brewster, D., ‘Descriptions of a monochromatic lamp for microscopical purposes &c., with remarks on the absorption of prismatic rays by coloured media’, Transactions of the Royal Society of Edinburgh, ix (1822), 435.Google Scholar

⁸ Young, T., ‘An account of some cases of the production of colours’, Philosophical transactions, xcii (1802), 395.Google Scholar

⁹ Herschel, to Brewster, , 24 07 1822Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’ (uncatalogued); also Herschel, to Brewster, , 7 08 1822Google Scholar, ibid., vol. xix. 27.

¹⁰ Herschel, to Babbage, , 2 12 1821Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xx. 130.Google Scholar

¹¹ Herschel, J. F. W., ‘On the rotation impressed by plates of rock crystal on the planes of polarization of rays of light’, Transactions of the Cambridge Philosophical Society, i (1822), 43–52.Google Scholar

¹² Herschel, J. F. W., ‘On the hyposulphurous acid and its compounds’, Edinburgh philosophical journal, i (1819), 8–29, 396–400.Google Scholar

¹³ See Herschel, , loc. cit. (9)Google Scholar; also Brewster, to Herschel, , 12 10 1822Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. iv. 256.Google Scholar

¹⁴ Herschel, to Babbage, , 16 10 1822Google Scholar, ibid., vol. xx. 152.

¹⁵ Herschel, J. F. W., ‘On the absorption of light by coloured media, and on the colours of the prismatic spectrum exhibited by certain flames; with an account of a ready mode of determining the absolute dispersive power of any medium, by direct experiment’, Transactions of the Royal Society of Edinburgh, ix (1822), 445–60.Google Scholar

¹⁶ Ibid., p. 456.

¹⁷ This is revealed in Brewster's obituary of Fraunhofer in American journal of science, xvi (1829), 301.Google Scholar

¹⁸ Herschel, to Brinkley, , 11 12 1824Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xx. 193.Google Scholar

¹⁹ Herschel, to Brewster, , 28 11 1825Google Scholar, ibid., vol. xx. 255.

²⁰ Talbot, to Herschcl, (undated, but apparently written early in 1826)Google Scholar, ibid., vol. xvii. 234.

²¹ Talbot, W. H. F., ‘Some experiments on coloured flames’, Edinburgh journal of science, v (1826), 77–81.Google Scholar

²² Ibid., p. 78.

²³ Ibid., p. 81.

²⁴ Brewster, D., ‘Notes sur l'histoire de l'analyse spectrale’, Comptes rendus des séances hebdomadaires de l'Académie des Sciences, lxii (1866), 17Google Scholar. It is interesting to compare Talbot's 1826 paper with one published by Turner, Edward (‘On the means of detecting Lithia in minerals by the blowpipe’, Edinburgh journal of science, iv [1825], 113Google Scholar.), which makes no mention of the use of a prism to distinguish between flames of similar colours.

²⁵ Talbot, to Herschel, , 07 1826Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xvii. 261.Google Scholar

²⁶ Talbot, to Herschel, , 22 05 1827Google Scholar, ibid., vol. xvii. 263. This effect is also mentioned in Talbot, 's ‘Facts relating to optical science, no. 2’, Philosophical magazine, 3rd ser. vi (1834), 114.Google Scholar

²⁷ Talbot, to Herschel, , 31 05 1833Google Scholar, ibid., vol. xvii. 272.

²⁸ Talbot, to Herschel, , 29 10 1827Google Scholar, ibid., vol. xvii. 267.

²⁹ Faraday's diary 1820–62, ed. Martin, T. (7 vols., London, 1932).Google Scholar

³⁰ See Jones, H. Bence, Faraday's life and letters (2 vols., London, 1870)Google Scholar; also Williams, L. P., Michael Faraday. A biography (London, 1965).Google Scholar

³¹ Faraday, to Herschel, , 30 05 1826Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. vii. 172Google Scholar. Reproduced in Williams, L. P. (ed.), The selected correspondence of Michael Faraday (2 vols., Cambridge, 1971), i. 163.Google Scholar

³² Herschel, J. F. W., ‘Light’, Encyclopaedia metropolitana, iv (London, 1827), 409.Google Scholar

³³ Ibid., p. 409.

³⁴ Ibid., p. 409 (emphasis added).

³⁵ Ibid., p. 433.

³⁶ Foucault, L., ‘Note sur la lumière de l'arc voltaique’, first published in Journal de l'Institut (02, 1849), reprinted in Annales de chimie, lviii (1860), 476–8Google Scholar. Translated by Stokes, G. G. in Philosophical magazine, 4th ser. xix (1860), 193–7.Google Scholar

³⁷ Kirchhoff, G., ‘Uber die Fraunhofer'shen Linien’, Monatsberichte der Köninglich Akademie der Wissenschaften zu Berlin (1859), 662–5Google Scholar. Translated by Stokes, G. G., loc. cit. (36).Google Scholar

³⁸ Herschel, to Tyndall, , 21 07 1861Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xvii. 388Google Scholar. Cf. McGucken, , op. cit. (2), p. 7.Google Scholar

³⁹ Herschel, to Tyndall, , loc. cit. (38).Google Scholar

⁴⁰ Herschel, , op. cit. (32), p. 438.Google Scholar

⁴¹ Ibid.

⁴² See McGucken, , op. cit. (2), p. 9.Google Scholar

⁴³ A notable exception was W. A. Miller, but even his interest was not sustained. He published an interesting paper, ‘Experiments and observations on some cases of lines in the prismatic spectrum produced by the passage of light through coloured vapours and gases, and from, certain coloured flames’, Philosophical magazine, 3rd ser. xxvii (1845), 81–91Google Scholar, but contributed, nothing further until the 1860s, when his work on stellar spectra, carried out with William Huggins, was of some importance.

⁴⁴ Frankland's question came in the course of a discussion on spectra at the Chemical Society, following the paper by Roscoe, H. E. (mentioned below), which was reported in Chemical news, iv (1861), 130–3.Google Scholar

⁴⁵ See, for example, the comments on the atomic theory by Liebig, in his Familiar letters on chemistry (2nd edn., London, 1851)Google Scholar. Cf. the account of the reception of Newland's work given in Van Spronsen, J. W.'s paper ‘One hundred years of the law of octaves’, Chymia, xi (1966), 135.Google Scholar

⁴⁶ Herschel, to Talbot, , 28 12 1830Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xxv (1). 15.Google Scholar

⁴⁷ Royal Society MSS., Fellows' certificates, 1831.

⁴⁸ Babbage, C., Reflections on the decline of science in England and on some of its causes (London, 1830).Google Scholar

⁴⁹ For further information see Orange, A. D., ‘The origins of the British Association for the Advancement of Science’, The British journal for the history of science, vi (1972–1973), 152–76.CrossRefGoogle Scholar

⁵⁰ Herschel, to Brewster, , 25 11 1831Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xxv (2). 30Google Scholar; also Brewster, to Herschel, , 1 12 1831Google Scholar, ibid., vol. iv. 262.

⁵¹ Brewster, D., Treatise on optics (London, 1831).Google Scholar

⁵² Like Newton, Brewster preferred the corpuscular theory of light, but, unlike him, refused to accept that colour and degree of refrangibility were invariably associated. He claimed that light of a single degree of refrangibility, produced by prismatic analysis, could be resolved still further by the use of coloured filters, and conversely that light of any given colour might be found, in some proportion, throughout the complete spectrum. Brewster's views are set out, and defended against his critics, in ‘A reply to the Astronomer Royal on the new analysis of solar light’, Philosophical magazine, 4th ser. iv (1852), 401–16.Google Scholar

⁵³ Brewster, D., ‘Report on optics’, Report of the British Association for the Advancement of Science, 1832 (London, 1833), p. 319.Google Scholar

⁵⁴ Ibid., p. 321.

⁵⁵ The information was first disclosed in an aside in Brewster, 's paper ‘Observations on the absorption of specific rays with reference to the undulatory theory of light’, Philosophical magazine, 3rd ser. ii (1833), 360–3.Google Scholar

⁵⁶ Talbot, to Herschel, , 27 03 1833Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xvii. 270.Google Scholar

⁵⁷ The full account of Brewster, 's absorption experiments appeared in ‘Observations on the lines of the solar spectrum and on those produced by the Earth's atmosphere, and by the action of nitrous acid gas’, Transactions of the Royal Society of Edinburgh, xii (1834), 519–30.CrossRefGoogle Scholar

⁵⁸ Ibid., p. 527.

⁵⁹ Brewster, , op. cit. (55), p. 363.Google Scholar

⁶⁰ Airy, G. B., ‘Remarks on Sir David Brewster's paper on the absorption of specific rays’, Philosophical magazine, 3rd ser. ii (1833), 423.Google Scholar

⁶¹ von Wrede, F., ‘An attempt to explain the absorption of light according to the undulatory theory’, Taylor's scientific memoirs, i (1836), 477–502Google Scholar; translated from Annalen der Physik und Chemie, xxxii (1834), 353Google Scholar. It is worthy of note that von Wrede saw the spectral lines as providing further evidence of the molecular nature of matter and as supporting Ampère's hypothesis.

⁶² See the Editor's footnote in Philosophical magazine, 3rd ser. x (1837), 355.Google Scholar

⁶³ Talbot's delay in publication is explained in the letter cited above (note 56). Meanwhile a brief account of the phenomenon had been published by Daniell, J. F. and Miller, W. H. in ‘Report of the proceedings of the Cambridge philosophical society’, Philosophical magazine, 3rd ser. ii (1833), 381.Google Scholar

⁶⁴ Herschel, J. F. W., ‘On the absorption of light by coloured media, viewed in connexion with the undulatory theory’, Philosophical magazine, 3rd ser. iii (1833), 401–12.Google Scholar

⁶⁵ Ibid., p. 405.

⁶⁶ Ibid., p. 407.

⁶⁷ Herschel's correspondence with Wheatstone indicates further interest in experiments to illustrate analogies between sound and light: e.g. Wheatstone, to Herschel, , 23 08 1825Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xviii. 144Google Scholar. For the interesting suggestion that Wheatstone's acoustic work influenced the development of Faraday's field theories, see Williams, , op. cit. (30), p. 177.Google Scholar

⁶⁸ Herschel, , op. cit. (64), p. 410.Google Scholar

⁶⁹ Herschel, , op. cit. (32), p. 433.Google Scholar

⁷⁰ Ibid., p. 409.

⁷¹ Herschel, , op. cit. (64), p. 402.Google Scholar

⁷² Evans, D. S., Deeming, T. J., Evans, B. H., Goldfarb, S. (eds.), Herschel at the Cape—Diaries and correspondence of Sir John Herschel 1834–8 (Austin, Texas, and London, 1969).Google Scholar

⁷³ Talbot, to Herschel, , loc. cit. (56).Google Scholar

⁷⁴ Talbot, M. H. F., ‘On the nature of light’, Philosophical magazine, 3rd ser. vii (1835), 113.Google Scholar

⁷⁵ Talbot, W. H. F., ‘Facts relating to optical science, no. 3’, Philosophical magazine, 3rd ser. ix (1836), 3.Google Scholar

⁷⁶ See Talbot, to Herschel, , 28 08 1839Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xxv (5). 15–16Google Scholar. Cf. Herschel, J. F. W., ‘On the action of the rays of the solar spectrum on vegetable colours, and on some new photographic processes’, Philosophical transactions, cxxxii (1842), 181–214.CrossRefGoogle Scholar

⁷⁷ See the Herschel-Draper letters, Royal Society MSS. ‘J. F. W. Herschel’, vol. vi.Google Scholar

⁷⁸ Diary of J. F. W. Herschel (copy), Royal Society MSS. The entries for 1838 show that he was heavily involved in the preparations for the forthcoming geomagnetic expedition to the Antarctic.

⁷⁹ Herschel, to Talbot, , 29 02 1848Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xxiii. 14.Google Scholar

⁸⁰ See Stokes, G. G., ‘On the change of refrangibility of light’, Philosophical transactions, cxlii (1852), 463–561.CrossRefGoogle Scholar

⁸¹ Herschel, J. F. W., ‘On the epipolic dispersion of light’, Philosophical transactions, cxxxv (1845), 143–54.CrossRefGoogle Scholar

⁸² Stokes, to Herschel, , 27 06 1856Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xvii. 31.Google Scholar

⁸³ Herschel, to Stokes, , 1 07 1856Google Scholar, ibid., vol. xvii. 32.

⁸⁴ Stokes, to Herschel, , 8 07 1856Google Scholar, ibid., vol. xvii. 33.

⁸⁵ See Stokes's letter to Whitmel, C., Nature, xii (1876), 188.CrossRefGoogle Scholar

⁸⁶ Stokes, G. G., Mathematical and physical papers, ed. Larmor, J. (5 vols., Cambridge, 1880–1905), iv. 367–76.Google Scholar

⁸⁷ Ibid., p. 373.

⁸⁸ See, for example, Knight, D. M., ‘The problem of the chemical elements, from Humphry Davy to Benjamin Brodie the younger’ (University of Oxford D.Phil, thesis, 1964)Google Scholar; also Brock, W. H., ‘Studies in the history of Prout's hypothesis’, Annals of science, xxv (1969), 49–80, 127–38.CrossRefGoogle Scholar

⁸⁹ Brown, 's claim appeared in his paper ‘Experimental researches on the production of silicon from paracyanogen’, Transactions of the Royal Society of Edinburgh, xv (1842), 229–46Google Scholar. Talbot and Herschel, while remaining sceptical about the validity of this claim, expressed support for the general concept of complex elements; see Talbot, 's letter to Herschel, , 6 04 1841Google Scholar, Royal Society MSS. ‘J. F. W. Herschel’, vol. xvii. 306Google Scholar, and Herschel, 's to Talbot, , 6 04 1841Google Scholar, ibid., vol. xvii. 306 (a).

⁹⁰ See Lockyer, N., Studies in spectrum analysis (London, 1878).Google Scholar

⁹¹ See his presidential address in Report of the proceedings of the British Association, 1871 (London, 1872), pp. xciii–xcvGoogle Scholar; also Thompson, S. P., Life of Lord Kelvin (2 vols., London, 1910), ii. 1201.Google Scholar

⁹² Roscoe, H. E., ‘On the application of the induction coil to Steinheil's apparatus for spectrum analysis’, a lecture delivered to the Chemical Society on 20 06 1861, printed in Chemical news, iv (1861), 118–22.Google Scholar

⁹³ From debate following Roscoe's lecture; op. cit. (44), p. 132.

⁹⁴ Herschel, to Tyndall, , loc. cit. (38).Google Scholar

⁹⁵ See, for example, Knight, D. M., ‘Steps towards a dynamic chemistry’, Ambix, xiv (1967), 179–97CrossRefGoogle Scholar; also Levere, T. H., ‘Faraday, matter, and natural theology—reflections on an unpublished manuscript’, The British journal for the history of sciente, iv (1968–1969), 95–8, and works cited therein.CrossRefGoogle Scholar

⁹⁶ Of some interest in this context is a paper by William West of Leeds, who remarked on the fact that a chemical element combined with another element, with heat, and with electricity in a fixed numerical ratio, according to the law of equivalent proportions, Dulong and Petit's law of atomic heats, and Faraday's law of electrolysis. See West, W., ‘On a remarkable analogy between ponderable bodies and caloric and electricity’, Philosophical magazine, 3rd ser. v (1834), 110.Google Scholar

⁹⁷ Mitscherlich, A., ‘On the spectra of compounds and simple substances’, Philosophical magazine, 4th ser. xxviii (1864), 169–89Google Scholar; translated from Annalen der Physik und Chemie, cxxi (1864), 459–88.Google Scholar

⁹⁸ Lockyer, , op. cit. (90).Google Scholar

⁹⁹ Dingle, , op. cit. (1).Google Scholar

¹⁰⁰ McGucken, , op. cit. (2).Google Scholar

¹⁰¹ See Brock, W. H., ‘Lockyer and the chemists’, Ambix, xvi (1969), 81–99.CrossRefGoogle Scholar

¹⁰² Bunsen, R. W., ‘Remarks on chemical affinity’, Philosophical magazine, 4th ser. v (1853)Google Scholar; translated from Comptes rendus, xxxv (1852), 835–6.Google Scholar

¹⁰³ A similar appeal for a re-examination of Berthollet's work was made by Story-Maskelyne, Nevil, in a paper entitled ‘On the connexion of the chemical forces with the polarization of light’, Philosophical magazine, 4th ser. i (1851), 428–32.Google Scholar

¹⁰⁴ Whewell, W., Novum organum renovatum (3rd edn., London, 1858), p. 221.Google Scholar

¹⁰⁵ Whewell, W., Philosophy of the inductive sciences (2 vols., London, 1840), i. 405–22.Google Scholar

¹⁰⁶ See Graves, R. P., Life of Sir William Rowan Hamilton (2 vols., Dublin, 1882), ii. 85.Google Scholar

¹⁰⁷ See Faraday's diary, op. cit. (29), vii. 462–5Google Scholar. Note in particular the absence of any dis cussion of the origin of line spectra in Faraday's speculative paper ‘Thoughts on ray vibrations’, Philosophical magazine, 3rd ser. xxviii (1846), 345–50.Google Scholar