DOCS.
233,
234
JULY
1916 231
Affectionate
greetings
to
you
and
your
family,
yours,
Albert.
Cordial
greetings
and
many
thanks
for
now
to
Zangger,
likewise
to
the
Zurchers.[5]
234.
From Théophile
de
Donder
[Brussels,]
14 July 1916
S[ir]
and
esteemed
Colleague,
I
acknowledge receipt
of
your
letter
of
the 8th
instant;[1]
I. I
was
happy
to
note
that the
eqs.
(371)
of
my
chap.
VII
are
identical to
yours (2a,
p. 845, 1915)
when
you set;[2]
Vg(Tki)Einstein
=
(Tik)DeDonder.
However,
then
I
note
your
eq.
(14)
p.
782
(XLIV,
1915)
must be modified in
the
following
manner;[3]
E
0K)Einstein
dxv
etc.,
in
other
words, among
these
4
relations
the
Iki’s
(i.e., my
Tik's)
must
appear.
I
have verified
this
fact
very carefully
in
3
different
ways.
II. You
note
that
in
the
case
where
Vg
=
1
and where
T
=
0
my
(tAu)DeD
must
coincide,
according
to
your
indications,
with
your
(tuA)Einst;
hence,
as
I
wrote
you
in
my
first
letter,[4]
this coincidence
does not
take
place.
I have verified
this
with the
ds2
which
appears
on p. 194, eq.
(4)
(report by
the late
K.
Schwarzschild
1916).[5]
This still leaves
me
perplexed?.
III.
I
found
d(tXu

tAV)/dxu
=0
The
tAu’g
diff.
from
the
tAu’s
and
(tuA)Einst =
general
case??
IV.
It
is
accurate to
say
that
of your
ten
equations my
eleven
eqs. can
be
deduced, i.e.,
those
that
result
from[6]
////
D(dx1...dx4)
=
0
and from
the
compl.
eq.
l
=
1/2E
Tkk.