DOCS.
61,
62
MARCH
1915 73
61. To Wander de Haas
[Berlin,
17
March
1915]
Dear de
Haas,
According
to
your method,
even
the
inducing
influence of
the
core poles’
de-
magnetization
field
can
be
virtually
eliminated
by
placing
the
identical,
oppositely
wound
coils
right
next
to
each
other:[1]
H'
B
I
=
B
+
H
B
=
H
+
I
I
=
B -
H
The little
rod’s
magnetic
field
produces
in
both
coils
almost
the
same
amount
of
oppositely
oriented
e.m.f. The little
coils
must have
the
smallest diameter
possible,
however.
With best
regards, yours,
A.
Einstein.
62. To
Tullio Levi-Civita
[Berlin,]
17
March
1915
Dear
Colleague,
I
shall be
delighted
if
next
time
you
write
me
in Italian.
I
spent
over
half
a
year
in
Italy
as
a
young
man[1]
and
at
that
time had the
pleasure
of
visiting
the
charming
little
town
of
Padova,
and
even now
I
still
enjoy being
able
to
apply
my
modest
knowledge
of
the Italian
language.
On the
other
hand, I
could not
muster
up
the
courage
to
write
you
in
Italian,
because
the
result would
be far
too
clumsy
and
unclear.
I
shall limit
myself
to
responding
to
your
last
letter.
We
can go
back to
the
earlier
one
anytime,
of
course.
Your
attack
culminates in
the
argument
that
in
reducing region E,
in which
the
terms
6guv
#
0,
in
general,
the
mean
values
6guv
do not
approach
a
limit.[2]
As
an
example you provide
the
function
A
=
A0
X
-
Xo
2
2
h