132
DOC.
178
SEPTEMBER
1909
thus,
A2
=
i
1

e
x
o
/
/
2
or A..
=
is
\
1

e
A°
,
where
Ai
=
current
fluctuation
per
unit
time.
Argument
not
rigorous,
because
fluctuation of Z
not
taken
into
account.[4]
The
other
argument:
x
=
0
x
x+1
x
=
l
Suppose
n0
electrons
(per
unit
time)
are
formed
at
x
=
0
by
an
external
cause. They
move
to the
right,
with
ionization
taking place
as
they
move.
In
a
unit
time,
n
+ A
electrons traceable
to
the
primary
n0
arrive
at
x
=
l.
The
time it
takes
for
the electron
to travel
between
x
=
0 &
x
=
l
shall be
neglected.
The
n0
primary
electrons
will
make
nŦX
+
(1)
electrons
pass
through
the
cross
section
x,
where
Ax
follows the
Gaussian
law
of
errors.
But for
n
the relation
nx =
n0e
(2)
holds. ß
is
obtained
in
the
following
way:
If, sloppily
but
harmlessly, one
treats
the unit
of
length
as a
differential,
then
nx+1
=nx
(1
+ ß)
(indices
denote
abscissas)