2 5 2 D O C U M E N T 9 M A Y 1 9 2 0
broadening of these lines due to anomalous dispersion. The asymmetry in this broadening was accen-
tuated when two nearby regions of anomalous dispersion overlapped. When measuring line positions
from the centers of lines this would be interpreted as a shift in position of the lines associated with
those regions of anomalous dispersion. For Julius’s original claim of mutual repulsion of Fraunhofer
lines, see Julius 1914; see also the rebuttal to this paper, St. John 1915, and Julius’s reply in Julius
1916. For a historical discussion of Julius’s work, see Hentschel 1991.
[11]Adams 1910; Evershed and Royds 1914.
[12]Albrecht 1915 and 1916.
[13]Royds 1915.
[14]St. John 1916, Evershed 1916, and Larmor 1916, which, together with Royds 1915, dealt a seri-
ous blow to Julius’s anomalous dispersion theory (see Forbes 1963, pp. 137–138, for a discussion).
In Larmor 1916, Joseph Larmor argued that for anomalous dispersion to produce coherent shifted
lines as proposed by Julius, the density gradient in the upper layers of the solar atmosphere would
have to be constant over such long length scales as to build up impossibly large densities in parts of
the solar atmosphere.
[15]The square brackets are in the original. This research was published as Julius 1921.
[16]Grebe and Bachem 1919; Evershed 1913; Royds 1914; Evershed and Royds 1914.
[17]Parentheses are in a darker ink. Another reference to Evershed’s “Earth effect” (see note 8).
Since Einstein’s theory called for no difference in the gravitational redshift between the limb and the
center of the Sun, Julius interprets the limb-center shift as being almost entirely due to his own anom-
alous dispersion effect, if the possibility of a Doppler component is ruled out.
[18]
Adams 1910.
[19]Therefore, according to Julius’s argument, the limb-center shift establishes the general nature
of the shifts caused by anomalous dispersion to the red, which is incompatible with his effort above
to accommodate both gravitational redshift and anomalous dispersion shifts in the Sun-arc spectra by
presuming that the dispersion shifts were predominantly to the violet.
[20]The reason that many solar physicists, from Adams on, tended to concentrate on the limb-center
shift was to avoid the difficulties encountered with the laboratory spectra measured in arc lamps.
[21]The parentheses are in pencil. The assumption that both the gravitational redshift and anoma-
lous dispersion operate in the Sun is incompatible with “experience.” For published versions of
Julius’s argument, see Julius and Cittert 1920, p. 109, and Julius 1921, p. 114.
[22]Julius had also consulted with Hendrik A. Lorentz on the status of the gravitational redshift. In
a letter to Julius of 18 April 1920 (NeUU, Archief Julius), Lorentz emphasized that the redshift pre-
diction was fundamental to the theory of general relativity and could not be dispensed with or easily
modified to conform to the observational data on the limb-center effect.
[23]Paul and Tatiana Ehrenfest; Julius’s wife, Betsy F. M. Julius-Einthoven (1867–1945), and
daughters, Louise Maria and Maria Elisabeth Willemine.
[24]See Einstein to Willem H. Julius, 5 December 1919 (Vol. 9, Doc. 192), in which Einstein told
Julius how much he enjoyed playing music at his house.
9. To Elsa Einstein
[Leyden] Sonntag. [9 May 1920]
Liebe Else!
Diesmal sagt sogar Ehrenfest, ich sei etwas schäbig à la Berlin; denn der feier-
liche Bratenrock ist etwas von den Motten
zerfressen[1]
Wir sind hier sehr glück-
lich, auch ohne die Geige. Ich bin neugierig, wie das mit ihr ablaufen wird. Du
wirst es schon
durchsetzen.[2]
Meine Ernennung hat Schwierigkeiten dank meinem
brenzligen polit. Renommé Es wird aber wohl
kommen.[3]
Die Ruhe hier ist wun-