92
DOC.
79
APRIL
1915
79. To Hendrik A. Lorentz
[Berlin,
28 April
1915]
Highly
esteemed
Colleague,
I
understand
your telegram. Upon reviewing
our
sign
determination, I
see
that there
is
an error
in
my
considerations.[1]
We
have
produced
as
closely
as
possible
the
case
of
perfect
resonance.
There the
torque
runs
ahead of
the
swing
in
phase by
n-2,
which
we
did
not
take into account.
It
would have been correct
to
arrange
the
solenoid and
the
incandescent
lamp
in series.
Then both
current
vectors would
coincide,
and
the
swing
produced by
the
trembling
of
the
filament
would differ at
perfect resonance
in
phase
by
r
from
the
swing
caused
by
the
gyro
effect
according
to
the
theory.[2]
Despite
this
oversight,
however,
the
proof
remains intact.[3]
More
out of luck
than
wit!!
The
corrected
diagram
looks
like
this:
torque through
gyro
effect
lamp
current
angular
range
corresp.
to
imperf.
resonance
for
light
indicator
oscillation
from
magn.
effect
coil
current
light
indicator
oscillation
from
lamp
filament oscillation
Approximate compensation
for
both
light
indicator
oscillations
is
only possible
with the correct
sign
of
the
effect.
With
affectionate
greetings, yours,
A.
Einstein.