352
REMARKS
ON
DOC.
51
have
the
same
value
on
both sides
of
the
boundary
surface
(YZplane).
Since
Dx
and
the
components
of
o
are
continuous,
we
can
replace the last
two
expressions
by
9)

i(dz
D

o
S
)
,
y
cK
x x
z;
ft2

i(oxDy

öS)
.
cK y
x'
We
get
rid of the
dependence
on
the
special
choice
of
the
position of
the coordinate
axes
relative
to
the
boundary
surface
element
considered
by
writing
the result
using
the notation
of
vector
analysis. If
the
subscripts
n
and
n,
respectively,
denote the
components
of
the
pertinent
vector
in
the
direction
of and perpendicular
to
the
normal of
the surface
of discontinuity,
then
it follows that
n
11
must
be
continuous
at
the
boundary
surface.
In
the
same
way
one
concludes
from
equation (2a)1
that the
components
,
n
£
+
i[D»]
n
are
continuous.
Bern and
Würzburg,
November
1908.
(Received
on
6
December
1909)
1loc. cit.