After they had tried in vain to appoint my father to the directorship of the Leiden Observatory, van de Sande Bakhuyzen was succeeded by his brother Ernst in 1897. And when Ernst Bakhuyzen died in 1918, Willem de Sitter became director of the observatory. De Sitter pondered a complete reorganization in order to bring the observatory to greater efficiency. Much unfinished material had piled up and he wished to put things onto a new track. After consulting with my father, he decided on an entirely new direction. Together with himself, there would be two adjunct-directors named who would tackle the three goals he had outlined. First, as director de Sitter himself would direct the department of theoretical astronomy. Second, Anton Pannekoek would direct the department of positional astronomy, because he had done this work at the observatory and was acquainted with the technical requirements. And third, Ejnar Hertzsprung1, who was my husband, would be responsible for the newly created astrophysics department. This arrangement seemed destined to great success. Although Hertzsprung was named, for political reasons the Ministry was set against naming Pannekoek as a government official.2 The latter opening remained unfilled since a suitable replacement could not be found in either Holland or elsewhere. Both de Sitter and Hertzsprung set to work with all their energy, but they sorely missed their third man because the positional work, which was pressing to be completed, remained undone.
KeywordsStellar System Monthly Notice Galactic Latitude Astrophysical Journal International Astronomical Union
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- 11.Because Jeans was present at the Edinburgh meetings of the BAAS, it was known to him prior to publication. Working independently, though relying on much the same data, Jeans reached basically the same conclusions as Kapteyn. See Jeans to Kapteyn, 28 December 1921 (University of Groningen Archives), and Jeans, J. H.: 1922, ‘The Motions of the Stars in a Kapteyn-Universe’, Royal Astronomical Society, Monthly Notices 82, 122–32. For a discussion of Jeans’s support of the ‘Kapteyn Universe’, with his force studies, and implications for the ‘island universe’ theory, see Smith, R.: 1982, The Expanding Universe: Astronomy’s ‘Great Debate’, 1900–1931, Cambridge University Press, Cambridge, England, pp. 104–5.ADSGoogle Scholar
- 12.For a thorough technical discussion of Kapteyn’s entire theory, see Paul, Robert E.: 1993, The Milky Way Galaxy and Statistical Cosmology, Chapter 6.Google Scholar
- 13.Kapteyn’s 1920/22 theory of the stellar system became the epitome of investigations for providing the classical solution to a statistical cosmology, and in the process came to be known as the ‘Kapteyn Universe’, a term coined by Sir James Jeans. See Paul, Robert E.: 1993, The Milky Way Galaxy and Statistical Cosmology, 1890–1924, Chapter 6.Google Scholar
- 14.Paul, Robert E.: 1993, The Milky Way Galaxy and Statistical Cosmology, p. 38.Google Scholar