DOC. 577 JULY
1918 603
so
you
probably will
barely
remember it.
We have evaluated
preliminarily
the
above type of considerations with
the
available
apparatus
1)
to conclude from
the
intensities of
the
Laue interferences
the
relative
numbers
of electrons and
thus the orientation
and
size
of the atoms’
charges
within
the
crystal
lattice.
The
experiments were performed
a
while
ago
already,[2]
I
told
Sommerfeld
and
Born
about
it,
as
the
occasion
arose.
Both
have meanwhile been
inspired by
it
to
arrive, along
other
routes
(piezoelectricity,
residual
rays),
at
figures
for such
charges.[3]
2)
We
could establish that, for diamond
(which
we
chose
because of its
low
ther-
mal
motion),
a
sharp
drop
in
intensity against
an
increase in
the
angle
between
scattered
ray
and
primary
ray
exists which
cannot
possibly
be covered
by present
considerations.
However,
this
drop
is
comprehensible
if
the
dimensions of
the
C
atom’s
system
of electrons
are
not infinitesimal
against
the
wavelength
of Roent-
gen
radiation.
Its
numerical evaluation hence leads
to
a
direct
determination
of
the
size
of
that
system.[4]
You
understand
that
all of this
is just
the
modest
beginnings
of
a
matter
which,
in
my opinion,
can
be
well
developed.
But
for this
we
need X
rays
of
arbi-
trary
wavelength
and
of sufficient intensity
and this
the
experimental equipment
I
presently
have at
my disposal
does not deliver.
It
fails for
short
wavelengths
owing
to
the
hv-relation,
and
it
is
precisely
there that
conditions
seem
to
me
to
be
present which,
as
it
seems,
as
far
as can
be concluded from
the
very incomplete
and
quite
unreliable
data,
must
point to
a
fault in classical
electrodynamics.
(I
am
thinking
here
of
a
quantization
of
the radiation emitted
from
a
free
electron.)
I
initially
opened
contact with Siemens
& Halske[5]
and ordered
a
cost
esti-
mate
there
for
the
necessary
apparatus.
This estimate
is
available and
amounts
to
16 030
marks,
the
high
total
of
which, naturally,
is
also determined
by
wartime
conditions. Then
I
looked around
regarding raising
this
money.
Chance
brought
me
into
dealings
with
Mr.
von
Miller
of
the
Deutsches Museum in
Munich,
who
referred
me
to
the
Jubilee Foundation of German
Industry.[6]
This foundation
has declared its
willingness
to
support
experiments
on
atomic structure
with
an
amount of
up
to
5000
marks,
under
the
condition
that
corresponding
contri-
butions
by
other
parties,
particularly
on
the
part of
the
government,
be made
toward
covering
the
costs.
A few days
ago
in
Göttingen
I
had
occasion to
speak
with
his
Excellency Schmidt,
who referred
me
to
you
and
the
K.
W.
Society.[7]
I
obviously
still cannot
operate
with the
apparatus
alone,
and
thus
I
come
to
the
request
of
whether
you,
through
the
K.
W.
Society,
were
perhaps
in
a
position
to
place
at
our
disposal
the
funds
for
this
apparatus.[8]
I could
then
apply
the
grant
by
the
Jubilee Foundation toward
the
running costs,
which
are
likewise
naturally