58
DOCS.
85,
86
FEBRUARY
1908
85.
To Johannes
Stark
[Bern,
17
February 1908]
I
find it
somewhat
strange
that
you
do not
recognize
my priority regarding
the
connection between inertial
mass
and
energy.[1]
I will
gladly
write
the article about
fluorescence[2]
that
you
requested
from
me, provided
you can give me a couple
of
months'
time
.
.
.
86.
From Paul Habicht
Schaffhausen, 19
February
1908
Dear
A. E.
Thank
you very
much for
your
card. As
regards
the
business
of
the
Maschinchen,
I
can
say
that
I
am very glad
that
you
protected
your
priority.[1]
I
consider
it likewise
urgent to publish
the construction
designs,
but
perhaps
one
could wait until
experiments
have
been carried
out.
But if
you
consider
it
better
to
proceed
with this matter
at
once,
I will be
very pleased
if
you
made
use
of
my
work
as
well.
Conrad has ferretted
out
a
mathematical
problem
of
great
interest
and,
as
he
believes,
novelty,
and has almost finished
gobbling
it
up,
at
least
the rawest
parts.
Your
postcard
turned
out to be
a
real
blessing
for
me,
because
it
really
cheered
me
up.
I
have discovered
various other
things,
and will write
to
you
about
it;
but
if
you
don't
have
enough
time
to
write,
don't trouble
yourself
and allow
me
to
go
on as
if
you
had
replied.
I
am
convinced
that
one can
very easily
lift off with such
a
device,
and that
there isn't
the
slightest
danger
of
tumbling
down,
especially
since the
two
propellers
can
also be viewed
as
gyrostabilizers
that
guarantee
a
smoother
run.
Forward motion
is
an
entirely
different
matter.
Indeed,
I
must
admit that
I cannot
get
completely
clear about
it.
Let
me
tell
you
how I
imagine
it.
1)
A horizontal
propeller
drives
the
whole
thing
forward,
the
two
vertical
propeller
surfaces
are
parallel to
the horizon.
I
don't
know whether
the
efficiency
of
the
two
vertical
propellers
decreases
or
increases
in this
case.
The
picture
would look
as
follows
if
there
were no
ribs
here.
Assume, e.g.,
that the
wind
velocity
=
the
peripheral vel.,
then the
upper
blade
apparently
has twice
the
peripheral vel,
and
the
lower
blade the
peripheral
vel.
=
0
thus,
the
effi-
ciency obviously
decreases,
because
shocks
cannot be avoided.
the
situation
is
totally
different when
we
have