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281
Heroes of the Telegraph
·
John Munro
118
Among
the
most
interesting
of
Siemens's
investigations
were
his
experiments
on
the
influence
of
the
electric
light
in
promoting
the
growth
of
plants,
carried
out
during
the
winter
of
1880
in
the
greenhouses
of
Sherwood.
These
experiments
showed
that
plants
do
not
require
a
period
of
rest,
but
continue
to
grow
if
light
and
other
necessaries
are
supplied
to
them.
Siemens
enhanced
the
daylight,
and,
as
it
were,
prolonged
it
through
the
night
by
means
of
arc
lamps,
with
the
result
of
forcing
excellent
fruit
and
flowers
to
their
maturity
before
the
natural
time
in
this
climate.
While
Siemens
was
testing
the
chemical
and
life-promoting
influence
of
the
electric
arc
light,
he
was
also
occupied
in
trying
its
temperature
and
heating
power
with
an
'electric
furnace,'
consisting
of
a
plumbago
crucible
having
two
carbon
electrodes
entering
it
in
such
a
manner
that
the
voltaic
arc
could
be
produced
within
it.
He
succeeded
in
fusing
a
variety
of
refractory
metals
in
a
comparatively
short
time:
thus,
a
pound
of
broken
files
was
melted
in
a
cold
crucible
in
thirteen
minutes,
a
result
which
is
not
surprising
when
we
consider
that
the
temperature
of
the
voltaic
arc,
as
measured
by
Siemens
and
Rosetti,
is
between
2,000
and
3,000
Deg.
Centigrade,
or
about
one-third
that
of
the
probable
temperature
of
the
sun.
Sir
Humphry
Davy
was
the
first
to
observe
the
extraordinary
fusing
power
of
the
voltaic
arc,
but
Siemens
first
applied
it
to
a
practical
purpose
in
his
electric
furnace.
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