264
12 Coda
Shapley’s observations of no reddening towards M13; and the dimensions of
Shapley’s system are also wrong because of his assumption of no absorption
towards globular clusters that on the sky appear near the Milky Way is also
incorrect. Kapteyn may have had the dimensions in the Milky Way of his Universe completely wrong, but in two other respects he was surprisingly correct,
namely the distribution of the luminosity of the stars near the Sun (his ‘brightness curve’) and the structure and dynamics in the direction perpendicular to
the Milky Way.
12.5 Retirement and Mount Wilson
In 1920 the Kapteyns had to leave their upper floor at the Ossenmarkt, because
the owner wanted to use it himself. Shortly after the war, there was also a serious
shortage of housing in neutral Netherlands, but they could make use of two
rooms in hotel De Doelen on the Grote Markt for a longer period of time. They
were also allowed to take their own furniture there. In Hertzsprung–Kapteyn’s
biography [1] their rooms in the hotel were described as follows:
The large living room at the front of the house, where the piano and the oldfashioned couch stood, overlooked the large market square with the stately Martini tower on the right and the massive City Hall on the left. On Tuesdays and
Fridays it was Market Day, which brought with it a lot of bustle. One could sit
for hours in the deep window-sill looking at to the bustling movement without
getting tired. But madness broke out in the middle of the beautiful month of
May, when then there was noise and shouting at their doorstep the fair with its
merry-go-rounds and hippodromes, steam engines whistled and music thumped,
and the balmy spring air was filled with the smell of pancakes and hot machines.
And Groningen was partying, and it did not want to have their privileges taken
away from them. That was a busy, unpleasant time for the guests of the hotel.
The Kapteyns often took refuge and went elsewhere for peace and quiet, which
they could not find at home.
Kapteyn kept up a busy schedule at the university (see Fig. 12.8). But at
the end of the academic year in which Kapteyn turned seventy (1920–1921),
to be precise on July 7, 1921, Kapteyn had to retire. He had agreed to a
position as deputy director of the Sterrewacht Leiden for one day a week,
but his work in Groningen was coming to an end. On his retirement Pieter
van Rhijn (Fig. 12.9) was appointed as his successor as professor and director
of the Astronomical Laboratory ‘Kapteyn’. Kapteyn entrusted his students,
particularly Jan Hendrik Oort and Egbert Adriaan Kreiken, in the hands of
12 Coda
Shapley’s observations of no reddening towards M13; and the dimensions of
Shapley’s system are also wrong because of his assumption of no absorption
towards globular clusters that on the sky appear near the Milky Way is also
incorrect. Kapteyn may have had the dimensions in the Milky Way of his Universe completely wrong, but in two other respects he was surprisingly correct,
namely the distribution of the luminosity of the stars near the Sun (his ‘brightness curve’) and the structure and dynamics in the direction perpendicular to
the Milky Way.
12.5 Retirement and Mount Wilson
In 1920 the Kapteyns had to leave their upper floor at the Ossenmarkt, because
the owner wanted to use it himself. Shortly after the war, there was also a serious
shortage of housing in neutral Netherlands, but they could make use of two
rooms in hotel De Doelen on the Grote Markt for a longer period of time. They
were also allowed to take their own furniture there. In Hertzsprung–Kapteyn’s
biography [1] their rooms in the hotel were described as follows:
The large living room at the front of the house, where the piano and the oldfashioned couch stood, overlooked the large market square with the stately Martini tower on the right and the massive City Hall on the left. On Tuesdays and
Fridays it was Market Day, which brought with it a lot of bustle. One could sit
for hours in the deep window-sill looking at to the bustling movement without
getting tired. But madness broke out in the middle of the beautiful month of
May, when then there was noise and shouting at their doorstep the fair with its
merry-go-rounds and hippodromes, steam engines whistled and music thumped,
and the balmy spring air was filled with the smell of pancakes and hot machines.
And Groningen was partying, and it did not want to have their privileges taken
away from them. That was a busy, unpleasant time for the guests of the hotel.
The Kapteyns often took refuge and went elsewhere for peace and quiet, which
they could not find at home.
Kapteyn kept up a busy schedule at the university (see Fig. 12.8). But at
the end of the academic year in which Kapteyn turned seventy (1920–1921),
to be precise on July 7, 1921, Kapteyn had to retire. He had agreed to a
position as deputy director of the Sterrewacht Leiden for one day a week,
but his work in Groningen was coming to an end. On his retirement Pieter
van Rhijn (Fig. 12.9) was appointed as his successor as professor and director
of the Astronomical Laboratory ‘Kapteyn’. Kapteyn entrusted his students,
particularly Jan Hendrik Oort and Egbert Adriaan Kreiken, in the hands of