DOCUMENT 630 OCTOBER 1918 905
zu
sehen wünschen.
Der
wichtigste
Grundsatz
für
den
Experimentalphysiker
ist
aber die
Objektivität,
sonst
ist seine
ganze
Mühe wertlos.
Seien Sie sehr
herzlich
begrüsst von
Ihrem
ergebenen.
Ehrenhaft
Selen
Gas Farbe
Fallgesch
w.
.
103
cm/sec
Radius
a
.
106
cm
Photophor
Geschwindgk
103
cm/sec
Bewegl
B
.
107
Photo
phor
Kraft
U
=
B/B
.
1010
Dyne
Argon
rot 1.53 15.30 11.72 2.42 4.85
Stickstoff rot
1.91
15.26 14.37 3.05 4.70
Wasserstoff rot 5.16 15.15
38.68 8.09 4.78
TLS.
[10 345].
The table
[10 346]
is in the author’s hand.
[1]Doc. 605.
[2]Kurt Konstantinowsky;
see Konstantinowsky
1915,
pp.
287-291.
[3]See Ehrenhaft 1918a,
1918b and
Parankiewicz 1917;
Irene Parankiewicz.
[4]The paper
is
Ehrenhaft
1918a.
[5]See
Konstantinowsky
1915,
p.
288; Y2
is the
mean square displacement
per
second in
a given
direction.
[6]At
this
point
in the
original
text,
Ehrenhaft indicates
a
note in the
margin:
"Vide 6. Seite"
(i.e.,
the table
appended
to
this
document).
[7]Ehrenhaft refers to the fact that he had measured the
charge
of
individual
particles,
whereas
most
other
experimental
determinations
of
the
elementary charge were
determinations
of
mean
values for
large
numbers
of
particles or
measurements
of
the ratio
of
charge
and
mass
(see
Ehrenhaft
1918a,
pp.
73-75).
[8]Richard Bär (1892-1940)
was engaged
in
experimental
work in
Edgar Meyer’s
institute at the
University
of
Zurich. He had
presented
his
preliminary
results
to
a meeting
of
the Schweizerische
Physikalische
Gesellschaft
on
4
May
1918
(see
Bär
1918a).
The Annalen
paper
is
Bär
1918b. Bär’s
results contradicted those
of
Ehrenhaft and indicated that electrical
charge
had
an
atomistic character.
[9]Bär
performed
two kinds
of
experiments, using a setup
similar
to
Ehrenhaft’s
(see
Doc.
605,
note 4).
He first
determined
the
potential
needed
to
compensate
the
gravitational
force
on a
test
par-
ticle,
so
that it would remain in the
same postition.
He then measured the
potential
values
at
which
the
particle
would
just
descend and ascend. A series
of
experiments
was performed,
where the
same
particle was
studied with different values
of
its
electric
charge.
Bär found that the ratios
of
the
charges
were
rational numbers.
[10]Ehrenhaft and Kurt
Konstantinowsky’s
method
of
"narrowing
down"
("Einengung")
is used
by
Bär
to
evaluate the second
type
of
measurements described in the
preceding
note.
The
two
values
of
the
potential give an
upper
and lower bound for the exact
stopping potential
and thus for the electrical
charge. Repeating
the
measurement
for
a
series
of
different
charges on
the
same particle gives a
series
of
upper
and lower
bounds, not just
for
the various electric
charges,
but
also
for
their ratios. This
method allows
a good
test
of
the
rationality or
irrationality
of
these ratios. See Ehrenhaft
1918a,
pp.
31-35,
and
Konstantinowsky 1918, pp.
449-451,
for
discussions.
[11]See
Ehrenhaft 1914,
p.
104.