A Geologist among Astronomers: The Rise and Fall of the Chamberlin-Moulton Cosmogony,Part 2

Chamberlin to Clerke, 14 March 1906 (Box 4, folder 20, and Box 5, C-UC).

“Reminiscences by Prof. T. C. Chamberlin (Given Orally to Mr. J. V. Nash)”, Chicago, 5 October 1928, p. 42 (Typescript in Box 1, folder 4, C-UC). “Synopsis of the Stages of Study of Earth Genesis and Nebular Hypothesis by T. C. Chamberlin and F. R. Moulton, between 1896 and 1906”, 12 March 1906, in folder of miscellaneous notes, Box 5, C-UC. The memorandum was published by Chamberlin and Moulton in 1909; see ref. 110.

Chamberlin to Woodward, 28 October 1905 (Chamberlin file at CIW): “As implied in our reports, the planetesimal hypothesis was worked out by myself in essential independence of Dr. Moulton, as he was compelled, on account of his health, to spend a year in the west, and I hesitated to tax him under the circumstances … the health of Dr. Lunn during the year has been such as to unfit him for the very difficult mathematical inquiry on which he had made good progress last year. He has been on the verge of a nervous breakdown growing out of overstrain in connection with an educational experiment under adverse auspices.”

Chamberlin to Perisho E. C. , 29 February 1904 (Letterbook XVIII, p. 49, C-UC). Carl Snyder to T. J. J. See, 19 March 1906, in container 15, See papers, Library of Congress. Upham Warren , “The Nebular and Planetesimal Theories of the Earth's Origin”, American geologist, xxxv (1905), 202–20. One of the most enthusiastic early supporters of the planetesimal hypothesis was the American geologist Fairchild H. L. ; in a letter to Moulton, 2 March 1904, Chamberlin credited Fairchild with stimulating interest in the theory (Letterbook XVIII, p. 58, C-UC).

Chamberlin file at CIW. There is a reply from Chamberlin to Perrine, 27 March 1906, in Letterbook XX, p. 1, C-UC, but I have not found Perrine's letter.

She had failed to mention the planetesimal hypothesis in her book Modern cosmogonies (London, 1903); Chamberlin suggested that the publisher should paste “Recent” over the word “Modern” on the title page (Chamberlin to Clerke, 14 March 1906, p. 8, in Box 5, C-UC). She did remark briefly in another book on Chamberlin's statement that explosive projection could produce the spiral form of nebulae, granting that it may have some truth in it but that it involves events on a much smaller scale than those we must ascribe to spiral nebulae (Problems in astrophysics (London, 1903), 445).

Chamberlin to Frost, 2 March 1904 (Frost correspondence at Yerkes Observatory). For Chamberlin's comments on Frost's corrections see his letter of 17 March 1904, ibid. (copy in Letterbook XVIII, p. 95, C-UC).

Frost to Chamberlin, 15 March 1905 (Box 5, C-UC).

Frost E. B. , “The Contribution of Astronomy to General Culture”, Popular astronomy, xix (1911), 463–71, quotations from p. 467. In his memoirs Frost noted his early interest in the nebular hypothesis, and recalled that Chamberlin had been an enthusiastic member of a faculty club to which both belonged, but did not mention the Chamberlin-Moulton theory; see An astronomer's life (Boston, 1933), 16, 45, 220.

Popular astronomy, xiv (1906), 571. See Section 3 for Comstock's earlier correspondence with Chamberlin.

Ibid., 570. Asaph Hall (1829–1907), known for his discovery in 1877 of the two satellites of Mars, had retired from the Naval Observatory in 1891, then taught celestial mechanics at Harvard.

Ibid., 572.

Ibid., 570. Young Augustus Charles (1834–1908), a leading solar astronomer, retired from Princeton in 1905.

Aitken R. G. , “The Nebular Hypothesis”, Publications of the Astronomical Society of the Pacific, xviii (1906), 111–22. Aitken was known for his observations of double stars.

Poor C. L. , The solar system: A study of recent observations (New York, 1908), 304.

Townley S. D. , “Evolution of the Solar System”, Publications of the Astronomical Society of the Pacific, xvii (1905), 199–200.

Hale G. E. , The study of stellar evolution. An account of some recent methods of astrophysical research (Chicago, 1908), 182–6 and ch. xxi. Chamberlin thanked Hale for his favourable account in a letter written 27 May 1908 (copy in Letterbook XXI, 817, C-UC).

Schaeberle J. M. , “The Probable Volcanic Origin of Nebulous Matter”, Nature, lxxiii (1906), 296–7; he thought Chamberlin's invocation of the action of another body to account for the ejection of streams of matter from stars was unnecessary. T. J. J. See, “Significance of the Spiral Nebulae”, Popular astronomy, xiv (1906), 614–6; See criticized speculations on the condensation of spiral nebulae to systems of stars, an idea he considered “quite unsound” though it is “even given place in one treatise of Geology”.

See's publications are cited in refs 135–7.

Chamberlin to Frost, and Chamberlin to Moulton, both 13 December 1906 (copies in Letterbook XX, 400, 401, C-UC).

See refs 130 and 132.

Campbell W. W. , “The Evolution of the Stars and the Formation of the Earth”, Scientific monthly, i (1915), 1–17, 177–94, 238–55; see p. 192.

Ibid., 238–44.

Russell H. N. , “The Applications of Modern Physics to Astronomy”, Journal of the Royal Astronomical Society of Canada, xviii (1924), 137–64, 201–23, 233–63. Russell H. N. Dugan R. S. and Stewart J. Q. , Astronomy (Boston, 1926), 370–5; see also second edition (1930) and third edition (1935). Jacoby Harold , Astronomy, a popular handbook (New York, 1915), 358–60. Buchanan Daniel , “The Fallacy of the Nebular Hypothesis: Celestial Mechanics and other Facts that Demand a New Theory”, Scientific American supplement, lxxxi (24 June 1916), 402–3. Kippax J. R. , The call of the stars (New York, 1914), 260. McNairn W. H. , “The Story of Cosmological Theory”, Science, xlvi (1919), 599–607. Isabel Martin Lewis, Splendors of the sky (New York, 1919), 14–15. Todd David , Astronomy (New York, 1922). Wood C. , The outline of man's knowledge (New York, 1927), 247.

Darwin G. H. , “Cosmical Evolution”, British Association report (1905), 3–32; quotation from p. 20. This passage was omitted from the version Darwin published in Science, xxii (1905), 257–67. Reprints, extracts and translation of Darwin's address appeared in several other journals.

Chamberlin to Moulton , 2 November 1904 (Letterbook XVIII, 770, C-UC.

Chamberlin to Woodward , 7 October 1907, at CIW; Chamberlin to Woodward, 19 August 1908, in Letterbook XXI, 990, C-UC; Chamberlin to Moulton, 22 and 26 August 1908, in Letterbook XXI, 994, 1000, C-UC.

Chamberlin to Woodward , 19 August 1908, in Letterbook XXI, 990, C-UC; Chamberlin T. C. , The origin of the Earth (Chicago, 1916), see references to Darwin given in index.

Darwin G. H. , op. cit. (ref. 61), quotation from p. 932.

Bryant W. W. , A history of astronomy (London, 1907), 128, 246.

Dolmage C. G. , Astronomy to-day, 2nd ed. (London, 1909), 335f. According to the preface, dated 1908, the author died before this edition was published.

Gore Ellard J. , “The New Cosmogony”, Knowledge, n.s., iii (1906), 523–6; Popular astronomy, xiv (1906), 515–22; Astronomical essays (London, 1907), ch. 24 (quotation from p. 334).

MacPherson H. Jr , “Theories of Celestial Evolution”, Popular astronomy, xvii (1909), 418–23.

Stratton F. J. M. , “Tidal Problems”, Nature, lxxxi (1909), 102–3.

Stratton F. J. M. , “Cosmogony”, Monthly notices of the Royal Astronomical Society, lxx (1910), 366–8.

Nölke F. , Das Problem der Entwicklung unseres Planetensystems. Aufstellung einer neuen Theorie nach vorhergehender Kritik der Theorien von Kant, Laplace, Poincaré, Moulton, Arrhenius u. a. (Berlin, 1908), 63–69.

Ibid., 75. Referring to Moulton's Fig. 3 in his 1905 paper, Nölke pointed out that while particles whose aphelia lie between c and b tend to give the nucleus a forward rotation, those whose aphelia lie between c and a tend to produce retrograde rotation when they unite with the nucleus; and he thinks there should be as many of the second category as of the first. Moulton's discussion of this point is in fact defective, but Chamberlin's makes it at least plausible that there will be more collisions of the nucleus with particles of the first kind than with those of the second; see Chamberlin and Salisbury , Geology, ii, 64–81 and Figs 29, 30, 31.

Nölke , op. cit., 64, 78–9.

A reviewer in Nature, lxxviii (1908), 474, noted that Nölke found it easy enough to demolish the theories of his predecessors but suggested that his own theory would probably not survive an equally critical examination. Stratton said that Nölke's “claim to have explained many of the as yet unsolved problems of cosmogony is hardly substantiated by his work” but did not discuss his criticisms of the Chamberlin-Moulton theory (op. cit. (ref. 225), 368).

Henri Poincaré, Leçons sur les Hypothèses Cosmogoniques (Paris, 1911; 2nd ed., 1913).

Sageret Jules , Le Système du Monde de Pythagore à Eddington (Paris, 1931), 302–12. Veronnet Alexandre , Les Hypothèses Cosmogoniques Modernes (Paris, 1914).

Poincaré , op. cit. (ref. 230) (1913 ed.), pp. LXIII, LXVI–LXIX, ch. xi; “Le Demon d'Arrhenius”, Hommage à Louis Olivier (Paris, 1911), 281–7, reprinted in Poincaré's Oeuvres (Paris, 1951–1954), viii, 564–9.

Leçons (1913 ed.), 22–23; Jeans J. H. , Problems of cosmogony and stellar dynamics (Cambridge, 1919), 147–53, and Astronomy and cosmogony (2nd ed., Cambridge, 1929), 264; Kuiper Gerard P. , “The Formation of the Planets, Part II”, Journal of the Royal Astronomical Society of Canada, 1 (1956), 105–21 (p. 109). Struve Otto , “Henry Poincaré and his Cosmogonical Studies”, Sky and telescope, xvii (1958), 226–8.

See Chamberlin's report to Woodward, 12 March 1906, on Perrine's letter, quoted above (ref. 195).

I have assembled the evidence for this (not very controversial) statement in a paper on the rise of American astronomy (to be published).

Chamberlin to Hale G. E. , 20 April 1907 (copy in Letterbook XX, 789, C-UC).

Slipher V. M. to Wolf M. , 17 July 1914 (roll 5, frames 1450–1, Early correspondence of the Lowell Observatory, microfilm edition (Flagstaff, Arizona, 1973)). I am indebted to Miss Helen S. Horstman for supplying a copy of this letter, and to Dr Norriss S. Hetherington for informing me of its existence. See also Hetherington's forthcoming book, Beyond the edge of objectivity: The measurement of internal motions in spiral nebulae, for a discussion of the relation between the Chamberlin-Moulton theory and Slipher's observations. There is a brief remark on this point in Richard Berendzen, Hart Richard and Seeley Daniel , Man discovers the galaxies (New York, 1976), 105.

van Maanen A. , “Preliminary Evidence of Internal Motion in the Spiral Nebula Messier 101”, Astrophysical journal, xliv (1916), 210–28. The connection with the Chamberlin-Moulton theory was mentioned at the end of a preliminary announcement with similar title in Proceedings of the National Academy of Sciences, ii (1916), 386–90. See also Hetherington , Beyond the edge of objectivity , ch. 3; “Adriaan van Maanen and Internal Motions in Spiral Nebulae: A Historical Review”, Quarterly journal of the Royal Astronomical Society, xiii (1972), 25–39; “Edwin Hubble on Adriaan van Maanen's Internal Motions in Spiral Nebulae”, Isis, lxv (1974), 390–3; “The Simultaneous ‘Discovery’ of Internal Motions in Spiral Nebulae”, Journal for the history of astronomy, vi (1975), 115–25; Berendzen R. and Hart R. , “Adriaan van Maanen's Influence on the Island Universe Theory”, Journal for the history of astronomy, iv (1973), 45–56, 73–98; Berendzen, Hart and Seeley , Man discovers the galaxies, Section 3.

Fernie J. D. , “The Historical Quest for the Nature of Spiral Nebulae”, Publications of the Astronomical Society of the Pacific, lxxxii (1970), 1189–230; Berendzen Hart and Seeley , Man discovers the galaxies.

Chamberlin T. C. , review of Reid's article “The Planetesimal Hypothesis and the Solar System” ( American journal of science , January 1924), Journal of geology, xxxii (1924). 242–62 (p. 258). See also Chamberlin , The two solar families (Chicago, 1928), 135.

Campbell W. W. , op. cit. (ref. 212), 244–5. For Chamberlin's reply to this argument see his review of Reid (cited in ref. 240), 258.

For Moulton the final blow to the long-prevailing view that nebulae are “world-stuff in an early stage of evolution” was Bowen's discovery that gaseous nebulae contain the heavier elements found in the Sun, in the same proportions, rather than consisting purely of lighter elements from which the heavier ones might be manufactured ( Moulton F. R. . “Composition of Gaseous Nebulae”, Scientific monthly, xlviii (1939), 485–6).

Russell H. N. to Luyten W. J. , 26 November 1932, in Box 35, Henry Norris Russell papers at Princeton University Library.

Jeffreys H. , “On Certain Possible Distributions of Meteoric Bodies in the Solar System”, Monthly notices of the Royal Astronomical Society, lxxvii (1916), 84–112. In 1969 Jeffreys wrote the following note for the reprint of this paper: “The argument on volatilization of planetesimals needs modification on account of the result of A. L. Parson that the volatilized matter would recondense. But this makes the eccentricities of the orbits harder to understand than ever” (Collected papers of Sir Harold Jeffreys on geophysics and other sciences, iii (London, 1974), 105).

Jeffreys H. , “Theories Regarding the Origin of the Solar System”, Science progress, xii (1917), 52–62; The Earth (Cambridge, 1924). Holmes Arthur , “Radioactivity and the Earth's Thermal History”, Geological magazine , (6) ii (1915–16), 60ff (Holmes abandoned the hypothesis of a steadily-cooling Earth in 1925; see “Radioactivity and Earth Movements”, Transactions of the Geological Society of Glasgow, xviii (1931), 559–606 (p. 563)).

Jeffreys H. , “The Compression of the Earth's Crust in Cooling”, Philosophical magazine, (6) xxxii (1916), 575–91; “On Certain Geological Effects of the Cooling of the Earth”, Proceedings of the Royal Society, (A) c (1921), 122–49; “Origin of the Solar System. A Reply to ‘T.C.C.’”, American journal of science, (5) ix (1925), 395–405.

Jeans J. H. , “The Origin of the Solar System”, Nature, cxxviii (1931), 432–5 (p. 433). See also ref. 266.

Jeans J. H. , “The Stability of a Spherical Nebula”, Proceedings of the Royal Society of London, lxviii (1901), 454–5 [abstract] and Philosophical transactions, cxcix (1902), 1–53 [see p. 52], and “On the Density of Algol Variables”, Astrophysical journal, xxii (1905), 93–102 (pp. 98, 102).

Jeffreys Harold , The Earth (2nd ed., Cambridge, 1929), App. C. and “Developments in Geophysics”, Annual review of Earth and planetary science, i (1973), 1–13.

Jeans J. H. , Problems of cosmogony and stellar dynamics, 17, 131.

Chamberlin T. C. , “Notes on Jeans' Problems of Cosmogony and Stellar Dynamics”, 11 February 1920, p. 1 (typed copy in Box 3, C-UC). The memorandum appears to be addressed to one of his colleagues, other than Moulton, probably MacMillan W. D. , who did in fact write a critical review of Jeans's book including some of the points Chamberlin mentioned in this memorandum. See Astrophysical journal, li (1920), 309–33. MacMillan subsequently had his own reasons for hostility to Jeans added to those of Chamberlin: He felt that Jeans had usurped the credit for the idea that stars derive energy transforming their mass, an idea that MacMillan (and others) had published earlier. He wrote to Russell H. N. , on 28 November 1924, that “Jeans' reputation out this way is not worth a plugged nickel. We don't like his morals any better than we like his dynamics” (Box 31, Russell papers at Princeton).

Chamberlin , “Notes on Jeans' Problems …”, 3–4, 7, 8.

T. C. C., “Editorial. Our New Responsibility”, 17 February 1920 (typed copy in Box 3, C-UC). Jeans estimated that about 560 million years may have elapsed since the primeval rotating nebula began to break up into stars (Problems of cosmogony, 286).

Jeffreys Harold , The Earth (Cambridge, 1924), 3. Jeffreys gave a detailed critique of the Planetesimal Hypothesis in an Appendix (pp. 250–6), including an attempt to refute Chamberlin's argument that a hot fluid earth could not have retained water vapour and atmospheric gases. In another Appendix (pp. 257–9) Jeffreys stated that the main difference between his theory and that of Jeans was that the latter assumed that the Sun was so large at the time of encounter that it occupied the orbit of Neptune. Jeffreys considered this improbable, and argued that even for a much smaller sun the probability of encounter would not be impossibly small.

Ibid., 17. This remark is elaborated on p. 246 of Jeffreys's article in Science, cited in ref. 263 below.

T. C. C., Journal of geology, xxxii (1924), 696–716 (p. 699).

Jeffreys , “Origin of the Solar System. A reply to ‘T.C.C.’”, American journal of science, (5) ix (1925), 395–405 (pp. 397–8).

Chamberlin , “Diastrophism and the Formative Processes. XIII. The Bearings of the Size and Rate of Infall of Planetesimals on the Molten or Solid State of the Earth”, Journal of geology, xxviii (1920), 665–701 (pp. 666, 668, 679).

Chamberlin T. C. , The origin of the Earth (Chicago, 1916), 181, 184; “Jones' Criticism of Chamberlin's Groundwork for the Study of Megadiastrophism”, American journal of science , (5) iv (1922), 253–73 (p. 269); and The two solar families, p. x.

Oldham R. D. , “The Constitution of the Interior of the Earth as Revealed by Earthquakes”, Nature, cii (1918), 235–6; Knott C. G. , “The Propagation of Earthquake Waves through the Earth”, Proceedings of the Royal Society of Edinburgh, xxxix (1919), 157–208 (pp. 184–6); Jones William F. , “A Critical Review of Chamberlin's Groundwork for the Study of Megadiastrophism”, American journal of science, (5) iii (1922), 393–413. It was later suggested that this evidence may not count decisively against the planetesimal hypothesis; see Mather K. F. , “Earth Structure and Earth Origin”, Science, lxxxiv (1939), 65–70.

On this see for example Abbot C. G. , The Earth and the stars (New York, 1925), 231; Hobson E. W. , The domain of natural science, Gifford Lectures at University of Aberdeen, 1921–1922 (New York, 1968), 309; Joly J. , The surface-history of the Earth (Oxford, 1930), 164; Smart W. M. , The Sun, the stars and the universe (London, 1928), 283–5; anonymous review of Earth evolution and its facial expression by Hobbs W. E. , in Nature, cx (1922), 270–2; Jones Spencer H. , General astronomy (London, New York, 1922), 380; van Maanen A. , “Investigations on Proper Motion, tenth paper: Internal Motions in the Spiral Nebula Messier 33, NGC 598”, Astrophysical journal, lvii (1923), 264–78 (p. 276); Crommelin A. C. D. , “The Solar System”, in Hutchinson's splendour of the heavens, ed. Phillips T. E. R. and Steavenson W. H. (London, 1923), 80; de Bray Gheury M. , “L'Hypothèse Cosmogonique et la Pluralité des Mondes Habités”, Ciel et terre, xli (1925), 8–14; Menzel D. H. , Stars and planets (New York, 1931), 87.

Moulton F. R. , “The Planetesimal Hypothesis”, Science, lxviii (1928), 549–59.

Jeffreys H. , “The Planetesimal Hypothesis”, Science, lxix (1929), 245–6. Chamberlin's review is cited above, ref. 256.

Moulton , Science, lxix (1929), 246–8. For evidence of Chamberlin's resentment see the end of his “Reminiscences”, cited above, ref. 192, and the memorandum of 1920, cited in ref. 251.

“From an Oxford Note-book”, Observatory, lii (1929), 126–8.

Jeans J. H. , “The Planetesimal Hypothesis”, Observatory, lii (1929), 172–3.

Jeffreys , Observatory, lii (1929), 173–7.

H. D., Nature, cxxiii (1929), 555–7. Dingle acknowledged his authorship of this note in a later article, “The Origin of the Solar System”, Nature, cxxix (1932), 333–5, in which a chronological review of theories is presented. Here Dingle quoted a letter from Jeans admitting that the first proposal of a “Tidal origin for the solar system” was that published by Sedgwick W. F. , “On the Oscillations of a Heterogeneous Compressible Liquid Sphere and the Genesis of the Moon; and on the Figure of the Moon”, Messenger of mathematics, xxvii (1898), 159–73. Sedgwick's paper was unknown to other cosmogonists until he sent a copy of it to the editor of Nature who asked Dingle to look into the priority question.

Russell H. N. , The solar system and its origin (New York, 1935).

Spitzer L. Jr , “The Dissipation of Planetary Filaments”, Astrophysical journal, xc (1939), 675–88.

Jeans took this objection quite seriously but was ambivalent about whether it was really an argument against the theory. In his book The mysterious universe (New York, 1930, new rev. ed. 1932) he seemed to be rather pleased with the idea that life on Earth is the accidental result of an extremely unlikely stellar encounter, and that we may be unique in the universe. Yet he also argued that the probability was not so small after all, since stellar encounters would have been more frequent in an earlier stage of the expanding universe, and the Sun would have been much larger at the time of such an encounter. See Problems of cosmogony and stellar dynamics (Cambridge, 1919), 286; “Origin of the Solar System”, Nature, cxlix (1942), 695.

Reid H. F. , “The Planetesimal Hypothesis and the Solar System”, American journal of science, (5) vii (1924), 37–64.

Russell , op. cit. (ref. 269), 104: “Moulton concludes that, under certain circumstances, this rotation [due to infall of planetesimals on planetary nuclei] would have been direct and rapid; but his postulates have been criticized by Reid H. F. , who concludes that the rotation would be slow” (no reference given).

Reid , op. cit., 63.

T. C. C., review of Reid's paper in Journal of geology, xxxii (1924), 242–62 (p. 244).

Russell to Moulton , 29 December 1925 (copy in Box 35, Russell papers at Princeton University Library (hereafter cited R-PU)).

Moulton to Russell , 4 January 1926 (Box 31, R-PU).

Russell to Moulton , 8 June 1929 (copy in Box 35, R-PU).

Moulton to Russell , 12 June 1929 (Box 33, R-PU).

Nölke F. , Der Entwicklungsgang unseres Planetensystems (Berlin, 1930), 181–95. Russell H. N. , op. cit. (ref. 269), 104, 108, 110. Luyten W. J. and Hill E. L. , “On the Origin of the Solar System”, Astrophysical journal, lxxxvi (1937), 470–82. Page Thornton , “The Origin of the Earth”, Physics today , (6) i (October 1948), 12–24. Kuiper G. P. , “The Formation of the Planets, Part II”, Journal of the Royal Astronomical Society of Canada, 1 (1956), 105–21.

Jeffreys H. , “Collision and the Origin of Rotation in the Solar System”, Monthly notices of the Royal Astronomical Society, lxxxix (1929), 636–41. For further development of the collision theory see “The Early History of the Solar System on the Collision Theory”, ibid. , 731–8; “Origin of Solar System Explained in a New Theory”, New York Times, 3 May 1931, IX: 4.

Russell to Moulton , 29 December 1925 (Box 35, R-PU); Russell to Adams L. H. , 25 February 1927 (Box 34, R-PU).

Russell H. N. Dugan R. S. , and Stewart J. Q. , Astronomy (Boston, 1926), i, 463–8.

Russell to Moulton , 29 December 1925 and 15 March 1926 (Box 35, R-PU).

Eddington A. S. , The internal constitution of the stars (Cambridge, 1926).

Russell to Moulton , 15 March 1926, p. 8 (Box 35, R-PU).

Moulton to Russell , 10 April 1926 (Box 31, R-PU).

Russell to Moulton , 3 May 1926 (Box 35, R-PU).

Moulton to Russell , 4 January 1926 (Box 31, R-PU).

Russell to Adams L. H. , 25 February 1927 (Box 34, R-PU).

Russell H. N. , “Astronomical Books”, Saturday review of literature, (6) i (27 July 1929), 7.

Russell to Moulton , 4 June 1929 (Box 35, R-PU).

Russell H. N. , “Worlds from a Catastrophe”, Scientific American, cxlv (1931), 92–93.

Russell to Luyten W. J. , 10 December 1932 (Box 35, R-PU). In his letters to Jeffreys in 1934 (cited below) Russell said he preferred the collision theory to the tidal theory but found difficulties in both.

Russell to Mitchell S. A. , 24 February 1933 [i.e. 1934?] (Box 23, R-PU).

Russell to Jeffreys , 19 March 1934 (Box 34, R-PU).

Jeffreys to Russell , 2 April [1934] (Box 32, R-PU).

Russell to Jeffreys , 18 April 1934 (Box 34, R-PU).

Russell H. N. , The solar system and its origin (New York, 1935), 117. A detailed calculation by R. A. Lyttleton confirmed Russell's conclusion but showed that the tidal theory comes out worse than the collision theory; see “Dynamical Calculations Relating to the Origin of the Solar System”, Monthly notices of the Royal Astronomical Society, cxxi (1960), 551–69.

Jeffreys H. , “Origin of the Solar System”, Nature, cxxxvi (1935), 932–3. Jeans insisted that the tidal theory is “fundamentally on sound lines” though he had no answer to Russell's objection ( Jeans J. H. , “The Origin of the Planets”, Science and culture, iv (1938), 73–75).

See ref. 270.

Russell to Spitzer , 18 May 1939 (Box 35, R-PU).

“I had a wildish idea this morning …”, Russell to Jeffreys, 19 March 1934 (Box 34, R-PU). See also The solar system and its origin, 135. The idea was independently conceived (“before finishing reading Professor Russell's book”) and developed further by Lyttleton R. A. , a young British astronomer who was visiting at Princeton on a Commonwealth Fund Fellowship. See Lyttleton R. A. , “The Origin of the Solar System”, Monthly notices of the Royal Astronomical Society, xcvi (1936), 559–68.

Cameron A. G. W. and Truro J. W. , “The Supernova Trigger for Formation of the Solar System”, Icarus, xxx (1977), 447–61.

Kuhn T. S. , The structure of scientific revolutions (Chicago, 1962; second edition, 1970).

Kuhn T. S. , “Second Thoughts on Paradigms”, in The structure of scientific theories, ed. Suppe F. (Urbana, Ill., 1974), 459–82.

Jeans J. H. , Problems of cosmogony and stellar dynamics (Cambridge, 1919), 18.

Lakatos I. , “Falsification and the Methodology of Scientific Research Programmes”, in Criticism and the growth of knowledge, ed. Lakatos I. and Musgrave A. (Cambridge, 1970), 91–195.

Frankel H. , “The Career of Continental Drift Theory: An Application of Imre Lakatos' Analysis of Scientific Growth to the Rise of Drift Theory”, New Hampshire Bicentennial Conference on the History of Geology (preprint).

The deletion of the spiral nebula hypothesis might appear to violate the Lakatos dictum that each subsequent theory in the programme is constructed by adding auxiliary hypotheses to the previous one ( Lakatos , op. cit., 118). However I do not think one should insist on Lakatos's literal meaning in this case since the purpose of the auxiliary hypotheses is, after all, to protect the hard core from refutation by being subject to refutation themselves. As L. Laudan has recently pointed out, it is quite common for new theories to be generated by dropping as well as adding assumptions. See “Two Dogmas of Methodology”, Philosophy of science, xliii (1976), 585–97; Progress and its problems (Berkeley, 1977), 77. (This point was brought to my attention by Michael Gardner.)

Brush S. G. , The kind of motion we call heat (Amsterdam, 1976), ch. 9.

Lakatos , op. cit. (ref. 308), 119; italics in original.

See ref. 125. Stratton (op. cit.) used the nebular hypothesis though he admitted that it was no longer tenable without substantial modification. Pickering continued to support the nebular hypothesis supplemented by wandering ‘planetoids’ that could collide with stars. Pickering W. H. , “Why the Axes of the Planets are Inclined”, Popular astronomy, xxv (1917), 487–9; “Various Suggestions Relating to Stellar Evolutions, Planetary Genesis and Hyperbolic Comets”, ibid., xxviii (1920), 77–80.

Jeffreys , op. cit. (ref. 300). Painter G. S. , Science and evolutionary theory (Washington, D.C., 1940), 62–81. Armellini G. , “I problemi fondamentali della cosmogonia e la legge di Newton”, Rendiconti della R. Accademia dei Lincei, Classe di Scienze Fisiche, Mathematiche e Naturali, (6) xxv (1937), 209–15. Crommelin A. C. D. , “Recent Progress in Astronomy”, Reports of the Physical Society of London, v (1938), 82–99. Longwell C. R. , “Geology”, in The development of the sciences, ed. Woodruff L. L. (New Haven, 1941) ii, 147–96 (p. 189).

Feyerabend P. K. , “Explanation, Reduction, and Empiricism”, in Minnesota studies in the philosophy of science, iii, ed. Feigl H. and Maxwell G. (Minneapolis, 1962), 28–97; “Problems of Empiricism”, in Beyond the edge of certainty , ed. Colodny R. G. (Englewood Cliffs, N. J., 1965), 145–260. Brush S. G. , “Statistical Mechanics and the Philosophy of Science”, PSA 1976 (Proceedings of the 1976 Biennial Meeting of the Philosophy of Science Association), ed. Suppe F. and Asquith P. D. (East Lansing, Mich., 1977), ii, 551–84.

Brush S. G. , The temperature of history (New York, 1977), chs 3 and 4.

Darden L. and Maull N. , “Interfield Theories”, Philosophy of science, xliv (1977), 43–64.

Frankel H. , “Alfred Wegener and the Specialists”, Centaurus, xx (1976), 305–24.

Russell H. N. , op. cit. (ref. 291).