DOC.
122
SEPTEMBER
1915 131
122. To Hendrik A. Lorentz
[Berlin,]
23 September 1915
Dear
Colleague,
Your
letter
came
into
my
hands
only yesterday evening,
as
I
was
in Switzerland
for
some
weeks
to visit
my
children.[1]
I
agree
completely
with the
deletion
you
have
suggested
and
acknowledge fully
the
correctness of
your
arguments
in
this
regard.
I
should
think
I
may presume
Gruneisen’s consent with
the
deletion and
willingly
assume
responsibility
for
it.[2]
I
am
pleased
that
you
and
de
Haas have met with
success
in
analyzing
the
magnetic
effect.[3]
That
method
of attaching
the
coil
to
the
iron
core
in
order
to render harmless
the
obscuring
interactions between
coil
and
core
had
been
conceived of
by
de Haas
alone, by
the
way,
which
he
in his modest
way
does
not
seem
to
have told
you.[4]
Now I
also have
thought
up
a
simple
method
to
eliminate
that
source
of
error;
but
as
long
as
I
have
not
tried
it,
I do not want
to
be too
trusting.
It
involves commutating
the
core
by
a
single brief
electrical
impulse
in
the
(stationary)
coil. I
shall
see
if
I
can
manage
to
do it.
It
is
a
very
simple experiment,
should it
work;
I
shall write
you
and de Haas
about
it.[5]
I
am
very glad
that
de Haas
now
has
the
move
successfully
behind him and
is
living
and
working
in
a
healthy
and
enjoyable
environment.[6] Warmest
greetings
to
them both and
to
their
children.
My
thanks
for
now
for
Mrs.
de Haas’s
friendly
letter; I
am
going
to
write
to
them when
I
have
something
to
report
on
the
planned experiments. Today
I
had
great
pleasure
seeing
many
of
the
local
scholars of
high regard
declare
their
strong
opposition
to
the annexations
in
a
submission
to
the
Chancellor.
You
are
right
after all with
your
fine
optimism
and
your
faith
in advancement.
It
is
to be
hoped
that the
good
and reasonable
gain
the
upper
hand.[7]
I
did
not
understand
your
conclusion
regarding
the
damping
of sodium
light
in
the
atmosphere.
I do not
see
why
g2
should
not
be able
to
be
arbitrarily
larger
than
g1,
because of
the
validity
of
Rayleigh’s formula;
for
the
weakening
of
light
intensity
related
to
g2
would
clearly
contribute
nothing
to
the
scattering,
but
would
relate
to
a
real
absorption
of
light
(conversion
into
heat).[8]
You
say
nothing, however,
about
how
we
know
that
such real
absorption
does not take
place.-I
have
probably
misunderstood
you.
Your article
delighted
me.[9]
I
have
also found
a
proof
for
the
validity
of
the
[relativistic] energy-momentum
conservation
principle
for
the
electromagnet.
field taking gravitation
into
consideration,
as
well
as a simplified
covariant
the-
oretical
representation
of
the
vacuum
equations,
in which
the
“dual” six tensor
[Sechservektor]
concept proves
unessential.[10]
At
the
moment
I
am
occupied
with
studying
your paper.
Besides, I
am
reading
with
admiration
the
clever
pamphlet