240
DOCS.
244,
245 JULY
1916
him,
is
a
first-class achievement.[3]
I
did
not
mention him
because, frankly speak-
ing,
I
consider him too
old. I
do not know his
exact
age,
but
his
entire
work
actually
belongs
to
an
earlier
epoch.
While Kustner’s research
is
characterized
precisely
by
the
search for
new
avenues,
Müller
is
better
characterized for his
careful
application of
tested
methods
(previously
also
by
himself).[4]
But
even
if
the
type
of
method
is
disregarded
and
success
of
the
application
alone
is consid-
ered
instead,
Küstner’s researches
are
certainly
not inferior
to
Müller’s. In
my
opinion,
Küstner
is
the
man
who
can
be
expected
to
make
Potsdam
move
into
the
forefront: Müller would
perhaps
be able
to
keep
it
at
the
level
it
is.
Yours
truly,
W. de
Sitter.
245. To
Michele
Besso
[Berlin,] Monday.
[31
July
1916]
Dear
Michele,
Your
postcard
made
me
very happy,
as
did
your
prior
letter,
according
to
which
my
wife is
feeling
better
agai.[1]
Do
none
of
you
have
a
clear
insight
into
her
malady?
I
again
firmly
believe in
the
resilience
of
our
friendship.[2]
The “Uncle
Toby”
salutation
is
a
reminder of Sterne’s
novel,
the
main char-
acters
of
which
we
compared
ourselves
to
many
times in
Zurich.[3]
The
rotating
ring’s
field
in
the
proximity
of
the
axis is
found
as
follows.
The
field
in
first-order
approximation
easily
results from
a
direct
integration
of
the
field
equations.[4]
The
second-order
approximation
results from
the
vacuum
field equations to clos-
est
approximation.[5]
The first-order
approximation yields
the
coriolis
forces,[6]
the
second,
the
centrifugal
forces.
That the latter
come
out
correctly
is
self-
evident from
the
general
covariance
of
the
equations,
hence
actually calculating
it out
is
of
no
interest whatsoever
anymore.
This
interest
is
there
only
if it
is
not known whether
rotational transformations
are
among
the
“admissible”
ones,
that
is,
if
the
equations’
transformation
properties
are
not
clear, a
stage
which
has
finally
been
overcome,
thank
heavens.[7]
Heartfelt
greetings
also
to
Anna and
Vero, yours,
Albert.
[6]Recipient’s
appended
note:
“How is
this
supposed
to
work where
the
coriolis
forces
are
independent
of location?”