DOC.
188
NOVEMBER
1909
141
188.
To
Edgar
Meyer
Zurich,
18
November
[1909]
Dear
Mr.
Meyer:
Hallelujah!
You
were
right!
Out of
carelessness,
I
omitted that last
integration.
The latter
yields
the
formula[1]
i2
2V
I
i0
The factor
e
X°
that
comes
in
here
will
save
the
kingdom!
I
carefully
examined
the
whole
theory
today,
and confirmed the old calculation.
Only
the
addition of
this
simple
integration
was
needed
(also
in
the
calculation of the
total
current
strength)
in
order
to
arrive
at
the formula.
This shows
once again
how
dangerous
it
is to
rely
on
one's
instinct!
The
thing
with
the
y-rays
will
yield
a
positive
result.
I
know this from
Müller,[2]
whom I
questioned
about
the relative
fluctuations
as a
function of the distance of
the
radioactive substance
from the
tube
immediately
after
he told
me
about
experiments
of
this kind.
In
this
way one
also
obtains
at
once
the
number of molecules that
are
disintegrated
by
a
T-ray
quantum.
If
we
assume
that
this
number
is
m
and
is not
subject
to
any
fluctuations, and that,
on
the
average,
N
quanta
are
absorbed
per second,
then,
on
the
average,
the
quantity
of
electricity
sNmr
=
E
is
deposited
on
the
electrodes
during
time
r.
The
mean
fluctuation
A
of
E
is to
E
as
1
is to
\jNr is
to
1,[3]
hence
A
=
emsjNr
A2
-
=
em.
E
It
is
a
pity
that
one
cannot also
estimate
the
energy
of
the
absorbed
T-radiation,
otherwise
one
could also
determine
the
wavelength
of
the
T-radiation.-
Your letter
gave me great
pleasure,
but
you
should
not
flatter
me so
much.
My
courses are a
lot
of
work,
more
than
I
had counted
on,
so
that
I
cannot
do much
pondering
for
pleasure.
I will
read
Campbell's[4]
paper
when I have
time; at
any
rate, the
formula
I
gave you
is
definitely
correct.
With
greetings
to
you
and
your family, your
A.
Einstein
My
wife
sends her cordial
greetings.