198
DOCUMENT
142 NOVEMBER 1915
ALSX.
[70 411].
[1]This
letter
is
dated
on
the
assumption
that it
was
written before
receipt
of
Einstein
and
De
Haas
1915d
(Vol.
6,
Doc.
23).
[2]Wander
de Haas
was teaching
at
a
secondary
school in rural
Deventer,
the Netherlands
(see
Doc.
107,
note
3).
[3]Einstein
had,
in
1901,
after
graduating
from
the
ETH,
offered
instruction
to middle-school
pupils
in
Winterthur
and Schaffhausen
(see
Einstein
to Mileva
Maric,
9
May
1901
[Vol.
1,
Doc.
106]
and Mileva Maric to
Einstein, 13
November
1901 [Vol.
1,
Doc.
124]).
[4]Three
years
earlier Einstein
had asked Wilhelm Wien’s advice
on
the
possibility
of
an
experi-
mental test
of
the
equality
of
inertial and
gravitational mass
for
radioactive substances
(see
Einstein
to
Wilhelm
Wien,
10
July
1912
[Vol.
5,
Doc.
413]),
not
knowing
that such
a
test had
already
been
performed
(see
Southerns
1910).
[5]Einstein
refers to
De Haas’s
follow-up experiments on
molecular
currents,
on
which
a
paper
(De
Haas
1915)
was
published
on
18
October.
[6]A report on experiments
of
this
type was
presented to
the Deutsche
Physikalische
Gesellschaft
on
25
February
1916 and
published
as
Einstein
1916d
(Vol. 6,
Doc.
28).
See also Doc. 122 for
a
short
description
of
the
experiment.
[7]As
is
pointed
out in Einstein 1916d
(Vol. 6,
Doc.
28),
this effect
was
caused
by an eccentricity
in the
suspension
of
the bar.
[8]James
Clerk Maxwell’s
experiments on
molecular
currents
are
discussed
in
De Haas and
De
Haas
1915 and in
Galison
1987,
pp.
29-31.
[9]Samuel
Jackson Barnett
(1873-1956)
was a
physicist
at Ohio State
University,
who,
since
1909,
had done
experiments
similar to the
Einstein-De
Haas
experiment.
In
Einstein and
De
Haas
1915d
(Vol.
6,
Doc.
23),
which
was
submitted
15 November,
the authors
acknowledge
Barnett’s work and
admit that
they
had
only recently
learned
of
it.
See
Galison
1987,
pp.
52-56, and
Vol. 6,
the editorial
note,
“Einstein
on Ampère’s
Molecular
Currents,”
pp.
145-149, for
more on
Barnett’s work.
[10]At
this
point
in the
original
text,
one
of
the
recipients
indicates
a
note that he
or
she has
append-
ed at the foot
of
the
page:
“der
nur
mit
der
schlechten und nicht mehr mit
einer
guten
Drehbank
arbei-
ten
konnte.”
142. To
Hans Albert Einstein
[Berlin,
15 November
1915]
Mein lieber Albert!
Ich will
um Neujahr
in die Schweiz
kommen, um
mit Dir ein
paar
Tage zuzu-
bringen.
Prof.
Zangger
hat Dir
gewiss
schon den
Vorschlag gemacht.[1]
Wohin
möchtest
Du
am
liebsten
mit mir?
Natürlich
nicht
weit
von
Zürich
weg.
Prof.
Zang-
ger meinte,
wir
sollten
zu
Herrn
Besso.[2]
Ich
weiss aber
nicht,
ob Du das
gern
hast.
Vielleicht wäre
es
besser,
wenn
wir
irgendwo
allein
wären. Was
meinst
Du?
Sei mit Tete
geküsst
von
Deinem
Papa.
AKSX.
[75 886].
The
postcard
is addressed “Herrn
Albert
Einstein Gloriastr.
(Spitzkehre)
Zürich
Schweiz.,”
and
postmarked
“Berlin-Wilmersdorf
1
15.11.15. 2-3N[achmittags].”
[1]First broached to
Heinrich
Zangger
by
Einstein
a
month
earlier
(see
Doc.
130).
In
early
Novem-
ber,
Einstein-Maric
had
expressed
her
irritation
at
the involvement
of
Zangger
and
Michele
Besso in
planning
the rendezvous
(see
Doc.
135).
[2]Michele
Besso
had
invited the
Einsteins,
father
and
son,
to
Krummenau
(see
Doc.
133,
in
par-
ticular note
3).