Beyond the Galaxy: The Development of Extragalactic Astronomy 1885–1965,Part 2

Smith Robert W. , “Beyond the Galaxy: The development of extragalactic astronomy 1885–1965, Part 1”, Journal for the history of astronomy, xxxix (2008), 91–120. The present paper follows on directly from Part 1.

Hubble is the subject of an important recent biography by Christianson Gale E. , Edwin Hubble: Mariner of the nebulae (Chicago, 1995). Christianson is very good on Hubble's early life and the way he engaged in ‘self-fashioning’; for example, Hubble effectively cut ties with his family later in his life and generated a number of self-serving myths. While the book offers little new on the details or practice of Hubble's astronomy, it is the first book-length critical account of his life. See too Christianson Gale E. , “Edwin Hubble: A biographical retrospective”, in Freedman W. L. (ed.), Carnegie Observatories astrophysics series, ii: Measuring and modeling the universe (Cambridge, 2004), 19–30. Also very useful on the young Hubble are Osterbrock D. Brashear R. Gwinn J. , “Self-made cosmologist: The education of Edwin Hubble”, in Kron Richard (ed.), Evolution of the universe of galaxies: Proceedings of the Edwin Hubble Centennial Symposium (San Francisco, 1990), 1–18, and “Young Edwin Hubble”, Mercury, xix (1990), 1990–15. There are numerous works on Hubble's astronomy. See, among others, Hetherington Norriss S. , Hubble's cosmology: A guided study of selected texts (Tucson, 1996); idem, “Hubble's cosmology”, American scientist, lxxviii (1990), 1990–151; idem, The Edwin Hubble papers: Previously unpublished manuscripts on the extragalactic nature of spiral nebulae (Tucson, 1990); Hoskin Michael , Stellar astronomy: Historical studies (Chalfont St Giles, 1982), 154–67; Smith Robert W. , “The origins of the velocity—distance relation”, Journal for the history of astronomy, x (1979), 1979–64; idem, The expanding universe: Astronomy's ‘Great Debate’ 1900–1931 (Cambridge, 1982); and idem, “Edwin P. Hubble and the transformation of cosmology”, Physics today, xliii (1990), 1990–58. See also the essays by Norriss Hetherington on “Hubble's cosmology” and Robert W. Smith on “Cosmology 1900–1931” in Hetherington Norriss S. (ed.), Encyclopedia of cosmology: Historical, philosophical, and scientific foundations of modern cosmology (New York and London, 1993), 285–96 and 116–26. Although designed as a textbook, Berendzen Richard Hart Richard Seeley Daniel , Man discovers the galaxies (New York, 1976), is also an important guide to a substantial body of original research by the authors on extragalactic astronomy in the first few decades of the twentieth century. Sandage Allan , The Mount Wilson Observatory: Breaking the code of cosmic evolution (Centennial history of the Carnegie Institution of Washington, i; Cambridge, 2004), is described by the author as an informal history, but contains much on Hubble as well as the extragalactic astronomy pursued at Mount Wilson. Hubble's The realm of the nebulae (New Haven, 1936) is Hubble's own overview of his researches to 1936.

An excellent starting point on Yerkes and its telescopes is Osterbrock D. , Yerkes Observatory 1892–1950: The birth, near death, and resurrection of a scientific research institution (Chicago, 1977). For Osterbrock's view on the quality of Hubble's dissertation, see p. 73. On Ritchey's 24-inch telescope, see also Osterbrock D. , Pauper and prince: Ritchey, Hale, and big American telescopes (Tucson, 1993), 43–78.

E. Hubble to Shapley H. , 5 July 1922, Harvard Archives. In fact, the “stars” would later be established to be globular clusters. On Hubble's interpretation of M87 in advance of his discovery of Cepheids in the Andromeda Nebula, see also Hubble Edwin , “Messier 87 and Belanowsky's novae”, Publications of the Astronomical Society of the Pacific, xxxv (1923), 261–3.

On Hubble's research strategy, see Smith , The expanding universe (ref. 2), 112–17.

Wright W. H. to Slipher V. M. , 2 June 1925, Lowell Observatory Archives.

Hubble E. to Shapley H. , 19 February 1924, Harvard Archives.

Smith Robert W. , “Beyond the Big Galaxy: The structure of the stellar system 1900–1952”, Journal for the history of astronomy, xxxvii (2006), 307–42, pp. 317–24.

Smith , The expanding universe (ref. 2), 114–21.

“Finds spiral nebulae are stellar systems; Dr. Hubbell [sic] confirms view that they are ‘island universes’ similar to our own”, New York Times, 23 November 1924, 6.

Hubble E. to Russell H. N. , 19 February 1925, Princeton Archives. On the circumstances surrounding the public announcement of Hubble's Cepheid results on 1 January 1925, when H. N. Russell read a paper on his behalf to a joint meeting of the American Astronomical Society and the American Association for the Advancement of Science, see Berendzen R. Hoskin M. A. , “Hubble's announcement of Cepheids in spiral nebulae”, Astronomical Society of the Pacific leaflet , no. 504, June 1971. Owen Gingerich touches on Hubble's Cepheid results in his broad overview of “The mysterious nebulae, 1610–1924”, in the Journal of the Royal Astronomical Society of Canada, lxxxi (1987), 1987–28. This is also reprinted in Gingerich Owen , The Great Copernicus chase and other adventures in astronomical history (Cambridge, MA, 1992), 225–37.

Hubble E. to Shapley H. , 11 March 1925, Harvard Archives.

Sandage , The Mount Wilson Observatory (ref. 2), 528.

Transactions of the International Astronomical Union, iv (1932), 170.

Smith , The expanding universe, 135.

Hubble Edwin , “Angular rotations of spiral nebulae”, Astrophysical journal, lxxxi (1935), 334–5, and van Maanen A. , “Internal motions in spiral nebulae”, Astrophysical journal, lxxxi (1935), 1935–7. For Hubble's remarks on van Maanen's motions in his The realm of the nebulae (New Haven, 1936), see pp. 97–98. The account given in this paper offers only a sketch of the resolution of the Hubble—van Maanen controversy and more extensive versions are available from a number of sources, most notably the studies of Richard Hart and Norriss Hetherington. The controversy was first explored by Michael Hoskin in “Edwin Hubble and the existence of external galaxies”, Actes of the 12th International Congress on the History of Science (Paris, 1971), v, 49–53. Hart's results are presented in R. Berendzen and R. Hart, “Adriaan van Maanen's influence on the island universe theory”, Journal for the history of astronomy, iv (1973), 1973–56 and 73–98, and in R. Hart, “Adriaan van Maanen's influence on the island universe theory”, unpublished Ph.D. thesis, Boston University, 1973. Hetherington's The Edwin Hubble papers (ref. 2) centres on the dispute between Hubble and van Maanen, but contains substantial material on the wider context of van Maanen's researches and contains references to earlier papers on van Maanen by Hetherington. Later papers are Brashear R. S. Hetherington N. , “The Hubble—van Maanen conflict over internal motions in spiral nebulae: Yet more information on an already old topic”, Vistas in astronomy, xxxiv (1991), 1991–23, and Hetherington Norriss Brashear R. S. , “Walter. S. Adams and the imposed settlement between Edwin Hubble and Adriaan van Maanen”, Journal for the history of astronomy, xxii (1992), 1992–56. Hetherington also discusses van Maanen in Science and objectivity: Episodes in the history of astronomy (Iowa, 1988). On van Maanen's researches, see too Smith , The expanding universe (ref. 2), chaps. 2 and 3.

Hubble , The realm of the nebulae (ref. 2), 98.

Hubble Edwin , “NGC6822, a remote stellar system”, Astrophysical journal, lxii (1925), 409–33, “A spiral nebula as a stellar system, Messier 33”, Astrophysical journal, lxiii (1926), 1926–74, “Extra-galactic nebulae”, Astrophysical journal, lxiv (1926), 1926–69, and “A spiral nebula as a stellar system, Messier 31”, Astrophysical journal, lxix (1929), 1929–58.

Smith , “Beyond the Galaxy” (ref. 1), 98–100.

See, for example, Curtis H. D. , “The nebulae”, Publications of the Astronomical Society of the Pacific, xxix (1917), 91–103.

Hubble , The realm of the nebulae (ref. 2), 36.

Wolf Max , “Die Klassifizierung der kleinen Nebelflecken”, Publikationen des Astrophysikalischen Instituts Koingstuhl-Heidelberg, iii (1909), 109–12.

Hubble's early work on classification schemes has been very well-analysed by Berendzen R. Hart R. , “Hubble's classification of non-galactic nebulae, 1922–1926”, Journal for the history of astronomy, ii (1971), 109–19. See also Smith, The expanding universe (ref. 2), 147–64.

Hubble , “Extra-galactic nebulae” (ref. 18).

Helge Kragh offers a more realistic appraisal of the relationship between observations and theories in twentieth-century cosmology in his Cosmology and controversy: The historical development of two theories of the universe (Princeton, 1996). See especially his remarks on pp. 269–71.

Jeans James H. , Astronomy and cosmogony (Cambridge, 1928), 19.

On Jeans's evolutionary scheme, see Jeans James H. , Problems of cosmogony and stellar dynamics (Cambridge, 1919).

Hubble E. to Slipher V. M. , 4 April 1923, Lowell Observatory Archives.

International Astronomical Union transactions, ii (1925), 206.

For more details, see Berendzen Hart , “Hubble's classification of non-galactic nebulae, 1922–1926” (ref. 23), 114–15, and Smith , The expanding universe (ref. 2), 148–50.

Hubble , “Extra-galactic nebulae” (ref. 18), 352.

On Lundmark's advocacy of the island universe theory, see Smith , The expanding universe (ref. 2), chap. 3, and Holmberg Gustav , Reaching for the stars: Studies in the history of Swedish stellar and nebular research (Lund, 1999), 90–131.

Hart Berendzen , “Hubble's classification of non-galactic nebulae, 1922–1926” (ref. 23), 116–17; Smith , The expanding universe (ref. 2), 151–2; and Holmberg, Reaching for the stars (ref. 32), 101–5. Walter Baade would later argue that the schemes of Hubble and Lundmark were proposed almost simultaneously. “There was not much difference”, Baade judged, “between the two systems. Lundmark tried to classify many details in addition to the main features. It so happened that in the long run the simpler classification of Hubble won out, and it has been in general use since that time”: Walter Baade, Evolution of stars and galaxies, ed. by Payne-Gaposchkin Cecilia (Cambridge, MA, 1963), 12.

Shapley Harlow , “On the classification of extra-galactic nebulae”, Harvard College Observatory bulletin, no. 849 (1927), 1–4, p. 2.

Smith , The expanding universe (ref. 2), 154–6.

See Gingerich Owen , “Through rugged ways to the galaxies”, Journal for the history of astronomy, xxi (1990), 79–80; and Smith , “Beyond the Big Galaxy” (ref. 8), 327. As noted in the latter paper, the prominent Harvard astronomer Cecilia Payne-Gaposchkin later recalled that the Super-Galaxy hypothesis “sank like a stone”. Shapley described his hypothesis in “The Super-Galaxy hypothesis”, Harvard College Observatory circular, no. 350 (1930), 1–7. For Lundmark's views, see, for example, Lundmark Knut , “Are the globular clusters and the anagalactic nebulae related?”, Publications of the Astronomical Society of the Pacific, xlii (1930), 1930–30.

See Smith , “Beyond the Big Galaxy” (ref. 8), 21, and The expanding universe (ref. 2), 153–61.

Lindblad B. , “On the nature of spiral nebulae”, Monthly notices of the Royal Astronomical Society, lxxxvii (1927), 420–6.

Smith , “Beyond the Galaxy” (ref. 1), 102–5.

Paddock G. F. , “The relation of the system of the stars to the spiral nebulae”, Publications of the Astronomical Society of the Pacific, xxviii (1916), 109–5.

See Smith , The expanding universe (ref. 2), 166–8 and the references cited therein. On Wirtz's researches, an important recent paper is Seitter W. C. Duerbeck H. W. , “Carl Wilhelm Wirtz — A pioneer in observational cosmology”, in Modern cosmology in retrospect, ed. by Bertotti B. (Cambridge, 1990), 365–99.

Kerszberg P. , “The relativity of rotation in the early foundations of general relativity”, Studies in the history and philosophy of science, xviii (1987), 53–79. An important work on de Sitter's early researches into general relativity and the consequent exchanges between Einstein and de Sitter is Pierre Kerszberg's The invented universe: The Einstein—de Sitter controversy (1916–17) and the rise of relativistic cosmology (Oxford, 1989).

North J. D. , “The early years”, in Bertotti (eds), Modern cosmology in retrospect (ref. 41), 11–32, p. 17.

de Sitter W. , “On Einstein's theory of gravitation and its astronomical consequences. Third Paper”, Monthly notices of the Royal Astronomical Society, lxxviii (1917), 3–28, p. 28.

Eddington A. S. to Shapley H. , 30 December 1918, Harvard Archives.

Shapley H. Shapley M. B. , “Studies based on the colors and magnitudes in stellar clusters. XIV: Further remarks on the structure of the galactic system”, Astrophysical journal, l (1919), 107–40, p. 126.

On astronomers and general relativity, good starting points are Crelinsten Jeffrey , Einstein's jury: The race to test relativity (Princeton, 2006), and Hentschel Kurt , The Einstein tower: An intertexture of dynamic construction, relativity theory, and astronomy (Stanford, 1997).

Eddington A. S. , The mathematical theory of relativity (Cambridge, 1923), 161.

Eddington , The mathematical theory of relativity (ref. 48), 162.

Wirtz C. A. , “Einiges zur Statistik der Padialgeschwindigkeiten von Spiralnebeln und Kugelsternhaufen”, Astronomisches Nachrichten, ccxv (1922), cols 349–54. The translation of the quotation employed here is from Seitter and Duerbeck, “Carl Wilhelm Wirtz — A pioneer in observational cosmology” (ref. 41), 374.

Hubble , The realm of the nebulae (ref. 2), 110.

Lundmark K. , “The motions and distances of spiral nebulae”, Monthly notices of the Royal Astronomical Society, lxxxv (1925), 865–94.

Silberstein L. , “The curvature of de Sitter's space-time derived from globular clusters”, Monthly notices of the Royal Astronomical Society, lxxxiv (1924), 363–6.

Lundmark K. , “The determination of the curvature of space-time in de Sitter's world”, Monthly notices of the Royal Astronomical Society, lxxxiv (1924), 747–70. On the de Sitter effect more broadly, as well as Silbertstein's researches, see too John North, The measure of the universe (Oxford, 1965), 92–104.

Hetherington Norriss , “The development and early application of the velocity—distance relation”, unpublished Ph.D. thesis, Indiana University, 1970, 139.

Hubble Edwin , “Extra-galactic nebulae”, Astrophysical journal, lxiv (1926), 321–69, p. 368.

On the fight over Lowell's will, see Putnam W. L. , The explorers of Mars Hill: A centennial history of Lowell Observatory 1894 to 1994 (West Kennebunk, MN, 1994), 92–104. For an important biography of Percival Lowell, see Strauss David , Percival Lowell: The culture and science of a Boston Brahmin (Cambridge, MA, 2001).

Humason M. , “The Rayton short-focus spectrographic objective”, Astrophysical journal, lxxi (1930), 351–6.

For an overview on instruments and practices in astronomy in the nineteenth and twentieth centuries see Smith Robert W. , “Remaking astronomy: Instruments and practice in the nineteenth and twentieth centuries”, in Nye M. J. (ed.), The Cambridge history of science, v: The modern physical and mathematical sciences (Cambridge, 2003), 154–73, and “Engines of discovery: Scientific instruments and the history of astronomy and planetary science in the United States in the twentieth century”, Journal for the history of astronomy, xxxii (1997), 1997–77. Important works on this topic include Gingerich Owen (ed.), Astrophysics and twentieth-century astronomy to 1950 (The general history of astronomy, iv/A; Cambridge, 1984), King Henry C. , The history of the telescope (London, 1955), and Riekher Rolf , Fernrohre und ihre Meister (Berlin, 1990). Dieter B. Herrmann's The history of astronomy from Herschel to Hertzsprung (Cambridge, 1994), transl. and revised by Kriscunas Kevin , is a general history of astronomy that is sensitive to the changing material culture of astronomy. See too Jarrell Richard A. , “J. S. Plaskett and the modern large reflecting telescope”, Journal for the history of astronomy, xxx (1999), 1999–90.

In this use of ‘moral economy’, I am following McCray W. Patrick , “Large telescopes and the moral economy of recent astronomy”, Social studies of science , xxx (2000), 685–711. Although he did not use the term ‘moral economy’, John Lankford (with the assistance of Ricky L. Slavings) offered a detailed examination of the workings of the American astronomical community and its tacit and explicit assumptions in American astronomy: Community, careers and power, 1859–1940 (Chicago, 1997).

An example would be Michelson's measurements of stellar diameters. On this see DeVorkin David H. , “Michelson and the problem of stellar diameters”, Journal for the history of astronomy, vi (1975), 1–18.

Gingerich , “Through rugged ways to the galaxies” (ref. 36). The surveys noted by Shapley in the quotation will be discussed later in this paper.

Hubble Edwin Humason Milton , “The velocity—distance relation among extra-galactic nebulae”, Astrophysical journal, lxxiv (1931), 43–80, p. 57, and Hubble E. to Slipher V. M. , 6 March 1953, Lowell Archives.

Hubble Edwin , “A relation between distance and radial velocity among extra-galactic nebulae”, Proceedings of the National Academy of Sciences, xv (1929), 168–73, p. 168.

Hubble , “A relation between distance and radial velocity among extra-galactic nebulae” (ref. 64), 173.

Hubble E. to de Sitter W. , 21 August 1930, Huntington Library.

Ibid.

de Sitter W. , “On the magnitudes, diameters and distances of the extragalactic nebulae, and their apparent radial velocities”, Bulletin of the Astronomical Institute of the Netherlands, v (1930), 157–71.

Lemaître G. , “Un univers homogène de masses constante et de rayon croissant, rendant compte de la vitesse radiale des nébuleuses extra-galactiques”, Annales de la Société Scientifique de Bruxelles, xlvii (1927), 49–56. This was translated as “A homogeneous universe of constant mass and increasing radius accounting for the radial velocity of extra-galactic nebulae”, Monthly notices of the Royal Astronomical Society, xci (1931), 1931–90. It should be noted that the two papers are not identical in content. See also Kragh Helge , “The beginning of the world: Georges Lemaître and the expanding universe”, Centaurus, xxxii (1987), 1987–26.

The discovery of the expanding universe has spawned a large literature. One starting point is Kragh Helge Smith Robert W. , “Who discovered the expanding universe?”, History of science, xli (2003), 141–62.

Hubble Humason , “The velocity—distance relation among extra-galactic nebulae” (ref. 63), 80. It is worth noting that, as Edward Harrison has emphasized, cosmologists generally fail to distinguish between the redshift—distance law proposed by Hubble in his 1929 paper and the velocity—distance law that was established later on theoretical grounds. Although “both laws are indiscriminately referred to as Hubble's law … no general proof exists demonstrating the two laws are equivalent, and perhaps for that reason many astronomers since the time of Hubble have viewed with reservation the velocity interpretation of extragalactic redshifts. The failure to distinguish between the linear redshift—distance law (an empirical approximation of limited validity) and the velocity—distance law (a theoretical derivation of unlimited validity) leads to confusion and obscuration of the fundamental concepts of modern cosmology”. Edward Harrison, “The redshift—distance and velocity—distance law”, Astrophysical journal, cdiii (1993), 28–31, p. 28.

Humason Milton , “The apparent velocity of a nebula in the Böotis cluster no. 1”, Publications of the Astronomical Society of the Pacific, xlvi (1934), 290–2.

This issue returned again at the end of the twentieth century when the initial and tentative recalibration of the cosmic distance scale using the Hubble Space Telescope produced a value for the time since the Big Bang uncomfortably close to the ages of the stars. As a Space Telescope Science Institute press release put it in 1994, a “simple interpretation of the large value of the Hubble Constant, as calculated from HST observations, implies an age of about 12 billion years for a low-density universe, and 8 billion years for a high-density universe. However, either value highlights a long-standing dilemma. These age estimates for the universe are shorter than the estimated ages of some of the oldest stars found in the Milky Way and in globular star clusters orbiting our Milky Way. Furthermore, small age values pose problems for current theories about the formation and development of the observed large-scale structure of the universe”, Space Telescope Science Institute Press Release, STScI-1994-49, 26 October 1994. See also Pierce M. J. , “The Hubble constant and Virgo cluster distance from observations of Cepheid variables”, Nature, ccclxxi (1994), 385–9.

Kohler M. , “Beitrage zum kosmologischen Problem und zur Lichtausbreitung in Schwerefeldern”, Annalen der Physik, xvi (1933), 129–61. On the context of Kohler's investigations, see Kragh , Cosmology and controversy (ref. 25), 269–87. See also W. H. McCrea, “Observable relations in relativistic cosmology”, Zeitschrift für Astrophysik, ix (1935), 1935–314.

Hubble , “Extra-galactic nebulae” (ref. 18).

Hubble Edwin Tolman Richard C. , “Two methods of investigating the nature of the nebular red-shift”, Astrophysical journal, lxxxii (1935), 302–7, p. 335.

Hetherington Norriss , “Philosophical values and observations in Edwin Hubble's choice of a model of the universe”, Historical studies in the physical sciences, xiii (1982), 42–67.

Sandage Allan , “Beginnings of observational cosmology in Hubble's time: Historical overview”, in Livio M. Fall S. M. Madau P. (eds), The Hubble deep field: Proceedings of the Space Telescope Science Institute Symposium … (Cambridge, 1998), 1–26, p. 5. For one account on Hubble's views on the nature of the redshifts, see Kragh Smith , “Who discovered the expanding universe?” (ref. 70). Here the authors argue that Hubble never believed there was convincing evidence that the expansion was real.

Hubble Edwin , “Adventures in cosmology”, Astronomical Society of the Pacific leaflets, iii (1938), 120–3, p. 123. See also, for example, Edwin Hubble, “Red-shifts and the distribution of nebulae”, Monthly notices of the Royal Astronomical Society, xcvii (1937), 1937–13.

Zwicky F. , “On the redshift of spectral lines through interstellar space”, Proceedings of the National Academy of Sciences, xv (1929), 773–9, and “Die Rotverschiebung von extragalaktischen Nebeln”, Helvetica physica acta, vi (1933), 1933–27. The point that Zwicky might have viewed invoking a new principle to explain the redshifts in a positive light because of his approach to science was made by Norris Hetherington in “Philosophical values and observations in Edwin Hubble's choice of a model of the universe”, Historical studies in the physical sciences, xiii (1982), 1982–67, p. 46. On Zwicky's approach to science, see Zwicky F. , Morphological astronomy (Berlin, 1957).

Kragh , Cosmology and controversy (ref. 25), 61–67. As Kragh writes, “From 1932 to 1940 there appeared about seventy papers related in one way or another to Milne's theory, which means the theory had a predominant position in the period” (p. 64). On Milne, see also George Gale's important overview of “Cosmology: Methodological debates in the 1930s and 1940s”, The Stanford encyclopedia of philosophy, Summer 2002 edn, ed. by Zalta Edward N. , URL = http://plato.stanford.edu/archives/sum2002/entries/cosmology-30s/. See too Gale G. Urani J. , “Philosophical midwifery and the birth pangs of modern cosmology”, American journal of physics, lxi (1994, 66–73. It is important to remember that interest in general relativity was at a low ebb in the 1930s and that cosmology was often regarded in this period as a decidedly dubious enterprise. On the standing of general relativity, see Eisenstaedt Jean , “The low water mark of general relativity, 1925–1955”, in Howard Don Satchel John (eds), Einstein and the history of general relativity (Boston, 1989), 277–92.

Milne's cosmological theory is best summarised in his two books, Relativity, gravitation and world-structure (Oxford, 1935), and Kinematic relativity (Oxford, 1948). For a very early statement of his views, see Milne E. A. , “World structure and the expansion of the universe”, Nature, cxxx (1932), 1932–11. North's The measure of the universe (ref. 54) also has much on Milne's theory. North's book is also an indispensable source on the history of cosmology in the first six decades of the twentieth century.

Hubble E. to Mayall N. U. , 23 February 1934, Huntington Library.

Sandage Allan , “Current problems in the extra-galactic distance scale”, Astrophysical journal, cxxvii (1958), 513–26, pp. 520–6.

Osterbrock D. , Walter Baade: A life in astrophysics (Princeton and Oxford, 2001), 162–76, provides a detailed account of Baade's researches. See also Smith, “Beyond the Big Galaxy” (ref. 8), 334–6.

Baade , Evolution of stars and galaxies (ref. 33).

Lambert J. H. , Cosmologische Briefe über die Einrichtung des Weltbaues (Augsburg, 1761). This work is available in translation, with an introduction and notes, by Jaki Stanley L. , as Cosmological letters on the arrangement of the universe (New York, 1976). See also Hoskin , “The cosmology of J. H. Lambert”, in Stellar astronomy (ref. 2), 117–23.

See, among others, Charlier C. V. L. , “How an infinite world may be built up”, Arkiv för matematik, astronomi, fysik , xvi, no. 22 (1922), 1–34, and “An infinite universe”, Publications of the Astronomical Society of the Pacific, xxxvii (1925), 1925–91. On the context of Charlier's researches, see Holmberg , Reaching for the stars (ref. 33). Holmberg also discusses the works Charlier published in Swedish on this topic.

See Hubble , The realm of the nebulae (ref. 2). See too Hubble Edwin , “The distribution of extra-galactic nebulae”, Astrophysical journal, lxxix (1934), 8–76 (this paper was based on counts of some 44,000 nebulae on some 1,283 plates with the 100- and 60-inch Mount Wilson reflectors), “Effects of red shifts on the distribution of nebulae”, Astrophysical journal, lxxxiv (1936), 1936–54, and “Red-shifts and the distribution of nebulae”, Monthly notices of the Royal Astronomical Society, xcvii (1937), 1937–13.

Shapley Harlow Ames Adelaide , “A study of a cluster of bright spiral nebulae”, Harvard College Observatory circular no. 294 (1926), 1–8, p. 1.

Shapley Harlow Ames Adelaide , “A survey of the external galaxies brighter than the thirteenth magnitude”, Annals of the Astronomical Observatory of Harvard College, lxxxviii/2 (1932), 42–75, p. 43.

See, for example, the remarks in 1956 by Humason, Mayall and Sandage that “it is becoming increasingly evident that the nebular distribution is characterized by a predominant tendency to cluster …”, Humason M. L. Mayall N. U. , and Sandage A. R. , “Redshifts and magnitudes of extragalactic nebulae”, Astronomical journal, lxi (1956), 97–162, p. 135.

The development of Schmidt type telescopes is discussed in King Henry , The history of the telescope (London, 1955), 356–76. See too Osterbrock Donald E. , “Getting the picture: Wide-field astronomical photography from Barnard to the achromatic Schmidt, 1888–1992”, Journal for the history of astronomy, xxv (1994), 1994–14.

For his early researches, see especially Zwicky F. , “On the masses of nebulae and clusters of nebulae”, Astrophysical journal, lxxxvi (1937), 217–46, and “On the clustering of nebulae”, Publications of the Astronomical Society of the Pacific, l (1938), 1938–20.

Zwicky , “On the masses of nebulae and clusters of nebulae” (ref. 94), 217.

See the annual report of the Mount Wilson and Palomar Observatories for 1955, where, in describing Zwicky's work, it was noted “No evidence was found for a clustering of clusters to form super-clusters”: “Mount Wilson and Palomar Observatories”, Astronomical journal, lx (1955), 296–301, p. 298.

de Vaucouleurs G. , “Evidence for a local supergalaxy”, Astronomical journal, lviii (1953), 30–32, “The distribution of bright galaxies and the local supergalaxy”, Vistas in astronomy, ii (1956), 1956–1606, and “Further evidence for a local supercluster of galaxies: Rotation and expansion”, Astronomical journal, lxiii (1958), 1958–66.

Vasilevskis S. Osterbrock D. E. , “Charles Donald Shane”, Biographical memoirs of the National Academy of Sciences, lviii (1989), 489–511, p. 494. On the Lick 20-inch astrograph, see Osterbrock Donald E. , “Frank Ross, his Ross lens design, and the Lick Observatory 20-inch astrograph”, Journal for the history of astronomy, xxxviii (2007), 2007–73.

Shane C. D. , “The distribution of galaxies”, Vistas in astronomy, ii (1956), 1574–84, p. 1583.

On Shapley's use of the term ‘clouds of galaxies’, see, for example, Shapley Ames , “A study of a cluster of bright spiral nebulae” (ref. 90), 1, and, much later, Harlow Shapley, Galaxies (Philadelphia, 1943), 197.

Abell George O. , “The distribution of rich clusters of galaxies”, Astrophysical journal supplement, iii (1958), 211–88, p. 211.

Abell George O. , “The National Geographic Society — Palomar Observatory Sky Survey”, Astronomical Society of the Pacific leaflet, viii (1959), 1–8, p. 7.

Just K. , “A test for evolution in cosmology”, Astrophysical journal, cxxix (1959), 268–70.

Stebbins J. Whitford A. E. , “Six-color photometry of stars, VI. The colors of extragalactic nebulae”, Astrophysical journal, cviii (1948), 413–28.

Kragh , Cosmology and controversy (ref. 25), 276–9.

On the discovery of radio sources beyond the Galaxy, see Hey J. S. , The radio universe , 3rd edn (Oxford, 1983); Classics in radio astronomy (Boston, 1982), selection and commentary by Sullivan Woodruff T. III , and Smith F. Graham Lovell Bernard , “On the discovery of extragalactic radio sources”, Journal for the history of astronomy, xiv (1983), 1983–65. On the radio source counts and their role in the debate over the steady state theory, see Kragh Helge , Cosmology and controversy: The historical development of two theories of the universe (Princeton, 1996), 306–31; Gregory Jane , Fred Hoyle's universe (Oxford, 2005); and Mitton Simon , Fred Hoyle: A life in science (London, 2005), and the references therein. Woodruff T. Sullivan III's forthcoming Cosmic noise: A history of early radio astronomy will be essential reading for the early history of radio astronomy. See also Sullivan's “The entry of radio astronomy into cosmology: Radio stars and Martin Ryle's 2C survey”, in Bertotti (eds), Modern cosmology in retrospect (ref. 41), 309–30. Also in the same volume is Peter Scheuer's “Radio source counts”, 331–46. Scheuer was a member of Ryle's group at Cambridge. For an extensive analysis of the disputes around radio source counts from a sociological perspective see Edge David Mulkay Michael , Astronomy transformed: The emergence of radio astronomy in Britain (New York, 1976).

The literature on the cosmic background radiation and the lead-up to, and aftermath of, its discovery is extensive. Among many others, see Alpher R. A. Herman R. , “Early work on ‘Big Bang’ cosmology and the cosmic blackbody radiation”, in Bertotti (eds), Modern cosmology in retrospect (ref. 41), 129–58; Wilson Robert M. , “Discovery of the cosmic microwave background”, ibid., 291–308; and Brush Stephen G. , “Prediction and theory evaluation: Cosmic microwaves and the revival of the Big Bang”, Perspectives on science: Historical, philosophical and social, i (1993), 565–602. Perhaps the single most important source is Kragh, Cosmology and controversy (ref. 25).

Sciama D. W. , Modern cosmology (Cambridge, 1971), 39.