Virginia citizen. (Irvington, Va.) 1891-1921, 1907-07-26
NATURE OF LIGHTNING.
Recent Discoveries Made Through tn
Use Of thN C.c,.r.

Recent Discoveries Made Through the
Use Of the Camera.
Remarkable studies of the nature OF
lightning have been made by a gifted
DaniSh-American experimei,ter. under
the auspices OF the Smithsonian insti.
tuition. Not only has II been learned
that lightning flashes are made up of
innumerable shorter flashes, and that
streaks of lightning are really linked.
or chain lightning, but the existence
of black or invisible lightning has been
ascertained. The genius who has taken
lightning for his study is Alexander
Larsen, who came to this country from
Denmark few years ago, and whose
education in photography, chemistry
and electricity was picked up at night
school.
Several years ago Larsen wrote to
the Smithsonian institution, inclosing
photographs of lightning, which he had
taken with common hand camera,
and suggesting that il camera were
so geared as to be moved during light.
ming flashes the duration of the fash
might be determined and its nature
made clearer. The institution became
interested in the ingenious immigrants
work and granted him a small sum
with which to pursue his studies with
better equipment.
Larsen rugged up a revolving table.
upon which he placed cameras In such
position as to catch lightning flashes at
various phases. 1t was soon dIscoy-
cred that what is called q fash of
lightning is in reality succession of
flashes, following one another with al
most uncomfortable swiftness and de-
ceiving the eye with an appearance of
oneness. Mr.. Larsen counted upon his
sensitive plates as many as forty
flashes in single streak of lightning,
and is convinced that in the forty were
scores of swifter flashes which eluded
the camera.
Measurements were taken of the time
elapsing between the flashes or rushes
that could be seen on the negative. 1t
was found that some of the flashes
were 2-1OOO of second apart The
measurement was made by calculating
the width of the film and the move
ment of each camera.
about these rushes of lightning. but
the most striking fact learned was that
some of the rushes were not light. but
dark-that is, the electric impulse was
there, just the same as in the flashes.
but the camera did not catch any light
Repeated experiments established the
fact that there is such a thing as
olack lightning, or atmospheric cleo
trlcal discharges that are not visible.
and that they are mingled with dis
charges that are visble-the old fash
toned lightning. How is it accounted
for? Mr.. Larsen's own explanation is
as good as any other:
THE FASH he says, speaking of the
Hash that gives no light. "must have
given out light of wave length much
: shorter than the wave lengths of visi-
Die light and with power sufficient to
render the part of the plate struck bv
1t nonsensitive TO ordinary light. Such
a flash would appear black on a partial
ly Illuminated background or DO in
visible"
In other words, "black lightning is
lightning of such short light waves
that the illumination is not perceived
Dy the human eye or by the camera.
This has suggested the thought that
there may be light waves of such We
iocity as to be equally beyond the per-
ception OF the eye or the camera, pro-
ducing light so intense that the human
eye is not only incapable OF perceiving
II, but Is ignorant of it's existence
Washington Post.