DOCS.
280,
281
AUGUST-SEPTEMBER
1911 201
In
my
theory,
the shift
toward
the
red
is
based
on
the
assumption
that
the refractive
index
n0
that the solar
atmosphere
would
possess
at
the
place
of
a
given absorption
line
if this line
were
not there,
is greater
than
1;
the
mean
absolute value for
n
-
1
is
then
greater
on
the red
side of the
line
than
on
the violet
side.[3]
If
now-as
I
think-the
width
of
a
Fraunhofer
line is
mainly
determined
by
anomalous
diffusion
(and refraction),
then
one can
merely
state
that the
displacement
can
always
be
only a
fraction of the
width
(e.g., 1/10
or
1/20).
And
this
seems
to be in
good
agreement
with
observational
results,
for
according
to
Adams, Fabry,
and
Buisson,
and
others,
the
displacements
vary
greatly
in
magnitude
and
are on
the
order of
0.005
Ä,
while
the
widths
of the
lines
of
average
intensity
vary
between
0.07 and 0.16
A.[4]
The
question
then remains whether
in fact the width
of the
Fr. lines
can
be
based
essentially on
anomalous
dispersion.
I have
put
forward
the
hypothesis
that the
true
regions
of
absorption
are
well
defined;
the
regions
of
diffusion in
the
spectrum
then
extend
beyond
them.[5]
Further, it
is
at
least
probable
that molecular
dispersion
and
dispersion
due
to
irregular
refraction lead
to
a
noticeable
attenuation of
the
light
in
the solar
atmosphere,
since
even
in
the
relatively
thin
atmosphere
of
the
earth
such influences
come
into
play.
Based
on
this,
more or
less,
my
view
seems
to
me
to
be
well-grounded.
Of
course,
one
cannot
give
definite numbers
for
the
magnitude
of the diffusion in
the solar
atmosphere;
but
the
consequences
of the
hypothesis
agree
qualitatively
with
observation
in
almost
every
detail.
The
astrophysicists
do
not
"believe" in
a
great
influence of
anomalous
dispersion
on
the
phenomena,
or are
perhaps
afraid of
such
an
influence.[6]
But
this
does
not
get one
anywhere.
I
have
not
yet
come across
sound
objections,
ones
that
were
not
based
on
misunderstanding.
If
you are
interested
in this
matter,
I would be most
grateful
if from
time to time
you
were
to draw
my
attention
to
weak
spots
in
my
argumentation.
This
is
why
I
take
the
liberty
of
sending you
a
few
reprints.
281. To
Erwin Freundlich
Prague,
1
September 1911
Highly
esteemed
Colleague:[1]
Thank
you
so
much for
your
letter,[2]
which
naturally
interested
me very
much. I
would be
delighted
if
you
wished
to
tackle this
interesting question.
I know
perfectly
well
that
to
answer
it
through experiment is
no
easy
matter, for the
refraction of the solar
atmosphere
may
come
into
play.
But
one thing
can,
nevertheless,
be
stated
with
certainty:
If
such
a
deflection
does
not
exist[3]
then the
assumptions
of the
theory
are
not
correct.[4]
For
one
must
keep
in mind that,
even
though
plausible,
these
assumptions