DOC. 427
JANUARY 1918
435
427.
From Wilhelm
Schweydar
Potsdam, 21
Leipziger St.,
4 January 1918
Dear Mr.
Einstein,
The
main
purpose
of the
Geodet.
Inst.[1]
is to determine
the Earth’s
gravi-
tational
equipotential
surfaces,
a
problem
which cannot be
separated
from
the
question
of
the Earth’s
constitution. Connected with
this
is
the
study
of
the
tem-
poral
alteration
in
shape
of these
equipotential
surfaces
as
they
are
determined
by
the
fluctuations of
the
Earth’s rotational axis and
elastic
pliability
towards
deforming
forces.
The
largest
project
of
the International
Geodetic
since
1900
concerns
researching
the variation in
geogr.
latitudes
and
the
procession
of
the
Earth’s
axis. Modern
geodesy
can no
longer
be
segregated
from
geophysics,
ei-
ther
in
theoretical
or
methodological respects,
and
there
is
certainly
room
for
development mainly
in
the
direction
of
geophysics.
Advances and
problems
in
geodesy
have been
moving
in this
direction
as
well
for
a long
time,
and
the
Geodet. Inst.
can
be referred to
equally
well
as a
geophysical
institute.
For
the
direction
of
the
Institute,
it
would be desirable
that
an
individual be
chosen who
is
equipped
with
ample qualifications
in
mathematics
and
physics
and
who has
great
interest
in
geophysics
and related
problems
of
a
geodesic
and
astronomical nature. Wiechert would be
very
suitable and also
acceptable,
in
consequence
of
his international
reputation
as
director
of
the
Central
Bureau
of
the Intern.
Geodetic[2]
which
is
connected
to
the
Institute. With
his
now
famous
paper
“Uber die
Massenverteilung
im Innern der Erde”
[“On
the Distribution
of
Mass in
the
Interior
of
the
Earth”] (Göttinger
Nachrichten)[3]
he has made
a
significant
advance in the
theory
of the Earth’s
shape
and
the
assessment
of
the Earth’s
interior,
which
was
fruitful
for
many
geophysical
and
geodesic
prob-
lems.
He
was
also
the
first
to
indicate
successfully
ways
to
utilize
earthquake
observations for
knowledge
of
the
composition
of
the Earth.[4]
With
his
talents
in
mathematics
and
physics,
it
is to
be
expected
that
he
will
promote
the
projects
at
the
Institute,
above
all,
from
the theoretical
point
of
view,
and
will act
as a
stimulus
and
helpful
adviser to his co-workers
at
the Institute.
His
lectures
on
geodesy
at
the
University
of
Göttingen
also do not draw him far afield from
the
responsibilities
of
pure surveying;
a
series
of
his lectures
on
geodesy
is
published
as
“Über
angewandte
Mathem.
u.
Physik
in ihrer
Bedeutung
für den
Unterricht
an
den höh. Schulen”
[“On Applied
Mathem. and
Physics
and Their
Importance
for
Instruction
at Schools of
High[er]
Education”].
Lectures, etc.,
published by
F.
Klein and Riecke
(Teubner
1900)
as Einführung
in
die
Geodäsie
[Introduction
to
Geodesy].[5]