142
DOCS.
188,
189
NOVEMBER
1909
In
fact,
the formula
should
read[5]
-
=
-(1
-
e~)e~
-
--,
where
r
is
the
time
during which,
on
the
average,
the
E2
2
1
i0r
quantity
of
electricity
E
passes
through
the tube.-
i0
=
saturation
current
in
absence
of
ionization.
A
=
fluctuation of E
189. Expert Opinion
on
the Dissertation
of
Hermann
Schüepp
[Zurich,]
30 November 1909
The
present
study
deals with
rapid
changes
in the
velocity
of mechanical
systems
consisting
of
rigid
bodies.[1]
First
(pages 1-14)
there
is
a
very
clear
presentation
of the
already
known
theory
of
such
processes;
in
a
supplement
(cf.
page
11),
the
theory
(that
of
Appell)
theory
is
formulated somewhat
more
generally,
in
order
to
make
it
easier
to
apply
the
theory
to
special problems.
Thereupon
(pp. 12-29)
the
general theory
is
applied
in
order
to
calculate the
apparent
friction
resistance
in
a moving car
that
arises
from
the
velocity changes (jolts)
experienced
by
the
wheels and
the frame
due
to
the
unevennesses
of
the
track
(considered to
be
rigid).
The results of
this
calculation,
which
is
performed correctly
and
expediently,
are
then
compared (referring to
Morin's
experiments)
with
experience
(pp.
29-37).
Even
though
the
experimental
material
used
was
not
ample
enough
to
provide
for
a
complete
confirmation of the
assumptions
that
underlie the
theory, through
skillful
application
of
the
scant
usable observational material
the author nevertheless succeeded
in
making
the
validity
of
his
results
plausible.
In the
last
part
of
the
study, again using
the
general
theory,
the behavior of
so-called
rod
chains
is
investigated
in the
case
of
a
momentarily
acting
cause
of
motion
(jolt).
On
pages
37-44
he
deals with
the
case
where the
chain links lie in
a
straight
line
at
the
moment
of the
jolt.
The
rest
of the
study (pp.
45-52)
contains
some
results
concerning
the
replaceability
of the rod
chain
by
a
sluggish, totally
flexible
spring.
Throughout
the
thesis,
the
presentation is
clear,
well
arranged,
carefully
thought
out,
and-as far
as
the
subject
permits-simple.
Since, according to
the
aforesaid,
the
study
here
discussed
proves
the author's
ability
to do
independent
scientific research, and since the
author
has satisfied
the
regulations
for the
acquisition
of
a
doctoral
degree
in all
other
respects
as
well, I
recommend that
his
application
be
accepted.[2]
A.
Einstein
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