11.1 The First World War
227
Kapteyn spoke out strongly anti-German in letters to Frederick Seares and
George Hale especially in relation to the important incident with the Lusitania.
The RMS Lusitania was a British ocean steamer, carrying passengers. On May
7, 1915, the ship was torpedoed and sunk by a German submarine; more
than half of the approximately two thousand passengers on board drowned.
This incident played an important role in the United States’ decision to give
up neutrality and declare war on Germany. In a letter to Frederick Seares,
Kapteyn called it an obvious example of ‘barbarism’, which had to open the
eyes of those who still thought somewhat positive regarding the German case.
‘That is not war, that is murder,’ he wrote.
He must have been worried about his daughter Henriette. After all, she was
married in 1913 to Ejnar Hertzsprung, who worked at the Astrophysikalisches
Observatorium in Potsdam. As mentioned, the Kapteyns visited their daughter and son-in-law in Germany in 1915. Because of the predicament of the
Hertzsprungs, which Kapteyn in a letter to George Hale shortly afterwards
characterized with the German term ‘unwohlwollende [uncomfortable or also
malicious] neutralität’, the war could not be a topic of discussion for them
or for Kapteyn with many colleagues. He reported however that those with
whom he actually was able to speak about it, had received great objections to
this ‘blödsinnige Krieg’ (stupid war), which they had still felt was justified at the
beginning. This was the intellectual class. Everything indicates that Kapteyn
took the position that Germany was guilty of starting the war and that he
supported the cause of the Allies.
Kapteyn was very concerned about the food supply and the welfare of his
daughter and son-in-law. In 1916 Henriette gave birth to a daughter who
was given the name Rigel—the brightest star of the constellation Orion. Rigel
Hertzsprung (1916–1993) was born in Rotterdam, where Henriette stayed
with her sister and brother-in-law Noordenbos, who both were physicians.
11.2 Radial Velocities
In addition to positions and luminosities of stars, spectroscopic observations
were of great importance; after all, with a spectrum, the type of the star can
be determined on the basis of the appearance and strength of dark absorption
lines, which are characteristic of the atoms responsible for absorbing starlight
in the outer parts. In the 1910s obtaining spectra was an enormously fast
growing activity, which would eventually lead to an understanding of the
structure, formation and evolution of stars. The important step of discovering
the systematics of stars in the Hertzsprung–Russell diagram were a fundamental
227
Kapteyn spoke out strongly anti-German in letters to Frederick Seares and
George Hale especially in relation to the important incident with the Lusitania.
The RMS Lusitania was a British ocean steamer, carrying passengers. On May
7, 1915, the ship was torpedoed and sunk by a German submarine; more
than half of the approximately two thousand passengers on board drowned.
This incident played an important role in the United States’ decision to give
up neutrality and declare war on Germany. In a letter to Frederick Seares,
Kapteyn called it an obvious example of ‘barbarism’, which had to open the
eyes of those who still thought somewhat positive regarding the German case.
‘That is not war, that is murder,’ he wrote.
He must have been worried about his daughter Henriette. After all, she was
married in 1913 to Ejnar Hertzsprung, who worked at the Astrophysikalisches
Observatorium in Potsdam. As mentioned, the Kapteyns visited their daughter and son-in-law in Germany in 1915. Because of the predicament of the
Hertzsprungs, which Kapteyn in a letter to George Hale shortly afterwards
characterized with the German term ‘unwohlwollende [uncomfortable or also
malicious] neutralität’, the war could not be a topic of discussion for them
or for Kapteyn with many colleagues. He reported however that those with
whom he actually was able to speak about it, had received great objections to
this ‘blödsinnige Krieg’ (stupid war), which they had still felt was justified at the
beginning. This was the intellectual class. Everything indicates that Kapteyn
took the position that Germany was guilty of starting the war and that he
supported the cause of the Allies.
Kapteyn was very concerned about the food supply and the welfare of his
daughter and son-in-law. In 1916 Henriette gave birth to a daughter who
was given the name Rigel—the brightest star of the constellation Orion. Rigel
Hertzsprung (1916–1993) was born in Rotterdam, where Henriette stayed
with her sister and brother-in-law Noordenbos, who both were physicians.
11.2 Radial Velocities
In addition to positions and luminosities of stars, spectroscopic observations
were of great importance; after all, with a spectrum, the type of the star can
be determined on the basis of the appearance and strength of dark absorption
lines, which are characteristic of the atoms responsible for absorbing starlight
in the outer parts. In the 1910s obtaining spectra was an enormously fast
growing activity, which would eventually lead to an understanding of the
structure, formation and evolution of stars. The important step of discovering
the systematics of stars in the Hertzsprung–Russell diagram were a fundamental