124 DOCS.
112,
113
AUGUST
1915
112. To Paul
Ehrenfest
[Berlin,
23 August
1915]
Dear
Ehrenfest,
Many
thanks
for
your
articles.
The
one on
osmotic
pressure
is
very
fine
and
amazingly
simple.[1]
The
suggestion
I
made
to
Lorentz
was
naive;
I realize
that
now.
The
wish
was
greater
than the
thought. I
would
so
much like to do
something
to
keep
our
colleagues
from
the
various
fatherlands united.[2]
Is
this
little
clutch
of
busy
intellectuals
not
our
only
“fatherland”
to
which
such
as
we
have
any
serious
attachment?
Should
even
these
people
have mentalities
that
are
solely
a
function of residence?
I
am
sending
two
offprints
for
Nordstrom.[3]
Do
tell him
that the
“Tolman
principle”
is
no more
than the
requirement
of covariance
under
similarity
trans-
formations, i.e.,
under
a
very special
type
of
linear
transformation,[4]
and
that
he
unjustifiably
contends
that
my
theory is
not in
keeping
with
it;[5]
as
you know,
the
former
maintains the
covariance of
arbitrary
linear
transformations.
Also
inform
him
that
he has been recommended
as
second-place
candidate
to
the
ex-
traordinary
professorship
at Berlin
University;
this
was an
indication
of Planck’s
sense
of justice.[6]
At
the
end of this
week I
am
traveling
to Switzerland for
about
3 weeks.
Then
I
shall be done with
traveling
for the time
being.
But
I
shall
gladly
descent
on
you
another
time,
if
possible
with
my
Albert.[7]
Cordial
greetings
to
you
all,
yours,
Einstein.
113. To
Wladyslaw
Natanson
[Berlin,]
Tuesday.
[24
August
1915]
Dear
Colleague,
I
accept your
friendly
invitation
with
great pleasure
and
shall arrive
punctu-
ally.[1]
Cordial
greetings, yours,
Einstein.
I
also
extend
my
sincere
thanks
to
Mrs. Natanson.