DOCS.
236,
237
JULY
1916
233
236. To
Théophile
de
Donder
[Berlin,]
17 July 1916
Dear
Colleague,
I.
My
equation
(14) p. 782,1915[1]
is
only
valid for the coordinate choice
V-g
=
1.
Generally,
instead of
Tvo,
Zvo
=
V-gTvu ought
to
be
inserted
into
the
same so
that
everything
is in full
agreement.
II.
That
your
tAu
does not
agree
with
my
tuA
has
a
profound
reason.
Since in
your
equation
(341)
you may
not in
general
set
l
= 0,[2]
your
[...]
yield[3] as
[ours?]?
V.
The
constant
k
has
no
physical
meaning,
because
it
is
determined,
as
you
know, by
the unit
of
mass.
A
variation
principle
of
the
form
S///Ldr=-1/2ETkk
is
peculiar.
Besides,
the
equations[4]
k-gkl(ik,
lm)
=
E(gTik
-
1/4gim[kk])
are
not consistent
with the
energy
law
of
matter.
Best
regards, yours truly,
A.
Einstein.
237. From
Michele
Besso
Zurich,
17 July
1916
Dear Albert,
I just
received
your
nice
letter
of
the
14th.[1]
There
is
not
the
least
reason
to
thank
me.
Whatever could be done
practi-
cally was
done
by
Mrs. Zürcher
and,
as
far
as was
necessary,
directed
by
Prof.
Zangger.[2]
I
had
to
play
an
all
the
more
passive
role
as
my presence
seems
to
affect
your
wife
unfavorably.
A
deception
absolutely
cannot be involved.
She
did not
complain
about
her
condition
is
not at issue here. Prof.
Zangger
reported
to
me
his
very
factual
observations;
these
I
passed
on
to
you,
in
essence.[3] I
mentioned
the
emotional
stress
as a
concurring
cause
because, as may
be determined
objectively,
[it]
has
improved again,
as
I reported to
you yesterday;
also the
boys are,
as
I
wrote
you,
provided
for
very
well
for
the
holidays.[4]