12.1 After the Great War
255
(1870–1947), director of the observatory in Copenhagen. The latter made
an effort to provide Germans access to material that was denied to them, as
in 1919 when others refused to share observations of a comet with German
astronomers. ‘Even my boys of 9 and 11 would never do such a thing’, he
said. Because of his influence, Kapteyn was asked to join the board of the
Astronomische Gesellschaft. Kapteyn agreed, not because he aspired to such
positions, but because it might help to repair the rift. He found Arthur Eddington at his side, who in 1920 was the only British astronomer who attended the
congress of the Astronomische Gesellschaft. Eddington carried a lot of weight;
after all, during the solar eclipse of 1919 he had verified the deflection of light
from stars by the gravitational force of the Sun predicted by Einstein.
12.2 Reorganization of the Sterrewacht Leiden
We have seen that Willem de Sitter was appointed professor in Leiden in 1908,
but that Ernst van de Sande Bakhuyzen became director of the Sterrewacht. I already described the conservatism of both the brothers van de Sande Bakhuyzen.
On March 3, 1918 Ernst died suddenly, about half a year before his retirement.
De Sitter became interim director and, with major involvement of Kapteyn,
started a reorganization. This was an extremely important phase in Dutch astronomy, because now the foundations could be laid for the consolidation of
the internationally prominent position that Dutch astronomy had assumed
under Kapteyn, and which turned out to be a prelude to its spectacular success
in the twentieth century. The focus of Dutch astronomy now was in Groningen, but Kapteyn must have realized that the conditions there were insufficient
to maintain and strengthen this position; together with de Sitter he safeguarded
the interests of Dutch astronomy by moving the center of gravity to Leiden.
The curators of Leiden University supported its Sterrewacht and astronomy
department wholeheartedly. Of course Kapteyn’s Astronomical Laboratory in
Groningen was maintained under his successor Pieter van Rhijn, but under
his leadership it soon became less prominent. Under de Sitter the Sterrewacht
Leiden became a prominent institution.
The ins and outs of this development have been described in detail by others, such as in Baneke’s book The discoverers of Heaven [25] and elsewhere
[109, 110]. The result was that Willem de Sitter became director of the
Sterrewacht and headed a theoretical department. In addition, two other departments were created, under the leadership of two deputy directors. The
astrophysics department was to be headed by Ejnar Hertzsprung, Kapteyn’s
son-in-law, who moved to Leiden from Potsdam for this and initially became
255
(1870–1947), director of the observatory in Copenhagen. The latter made
an effort to provide Germans access to material that was denied to them, as
in 1919 when others refused to share observations of a comet with German
astronomers. ‘Even my boys of 9 and 11 would never do such a thing’, he
said. Because of his influence, Kapteyn was asked to join the board of the
Astronomische Gesellschaft. Kapteyn agreed, not because he aspired to such
positions, but because it might help to repair the rift. He found Arthur Eddington at his side, who in 1920 was the only British astronomer who attended the
congress of the Astronomische Gesellschaft. Eddington carried a lot of weight;
after all, during the solar eclipse of 1919 he had verified the deflection of light
from stars by the gravitational force of the Sun predicted by Einstein.
12.2 Reorganization of the Sterrewacht Leiden
We have seen that Willem de Sitter was appointed professor in Leiden in 1908,
but that Ernst van de Sande Bakhuyzen became director of the Sterrewacht. I already described the conservatism of both the brothers van de Sande Bakhuyzen.
On March 3, 1918 Ernst died suddenly, about half a year before his retirement.
De Sitter became interim director and, with major involvement of Kapteyn,
started a reorganization. This was an extremely important phase in Dutch astronomy, because now the foundations could be laid for the consolidation of
the internationally prominent position that Dutch astronomy had assumed
under Kapteyn, and which turned out to be a prelude to its spectacular success
in the twentieth century. The focus of Dutch astronomy now was in Groningen, but Kapteyn must have realized that the conditions there were insufficient
to maintain and strengthen this position; together with de Sitter he safeguarded
the interests of Dutch astronomy by moving the center of gravity to Leiden.
The curators of Leiden University supported its Sterrewacht and astronomy
department wholeheartedly. Of course Kapteyn’s Astronomical Laboratory in
Groningen was maintained under his successor Pieter van Rhijn, but under
his leadership it soon became less prominent. Under de Sitter the Sterrewacht
Leiden became a prominent institution.
The ins and outs of this development have been described in detail by others, such as in Baneke’s book The discoverers of Heaven [25] and elsewhere
[109, 110]. The result was that Willem de Sitter became director of the
Sterrewacht and headed a theoretical department. In addition, two other departments were created, under the leadership of two deputy directors. The
astrophysics department was to be headed by Ejnar Hertzsprung, Kapteyn’s
son-in-law, who moved to Leiden from Potsdam for this and initially became