The sun. [volume] (New York [N.Y.]) 1833-1916, 1907-06-09
NATURE or LIGHTNING.
Discoveries Made Through Use OF Camera
at Smithsonian Institution.

From the Washington Post.
Remarkable studies OF the nature OF light
ming ave been made by a gifted Danish
American experimental under the auspices
OF the Smithsonian Institution. Not only
has it 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 liRhtning has been ascertained.
The genius who has taken lightning for his
study is Alexander Larsen. who came 10
this country from Denmark a few years ago,
and whose education in photography, chem
istry and electricity was picked up at night
school.
Several years ago larsen wrote to the
Smithsonian institution. enclosing photo
graphs OF lightning, which he had taken
with a common hand camera. and su ggesting
that IL a camera were so geared as to be move
during II ghtning flashes the duration Of the
fash might be determined and its nature
made clearer. The institution becam me inter-
ested in the ingenious immigrants work and
granted him a small sum with which 10 pursue
his studies with a better equipment.
Larsen rugged up a revolving table. upon
which he placed cameras In such position
as to catch lightning flashes at various phases.
II was soon disco vered that what is called
a fash OF liRhtninG Ia In reality a succession Of
flashes. following one another with almost
inconceivable swiftness and deceiving the
eye with an appearance OF oneness. Mr.. Lar
sen counted upon his sensitive plates as
many as forty flashes in a single streak Of
lightning. and Is convinced that in the forty
we're scores OF swifter flashes which eluded
the Csmera.
Measurements were taken Of the time
elspsing between the flashes OF rushes that
could be seen on the negative. II was found
that some OF the flashes we're 81 900 Of a sec
nnA anaF o Tia ~ am aAN ura paoAa -,
calcula ting the width Of the Aim and the
movement OF each camera.
Many obscure things we're noted about
these rushes OF lightning. but the most strik-
ing fact learned was that some of the rushes
we're not light but dark. That is. the electric
impulse was there. Just the same as In the
flashes. but the amera did not catch any
light.
Repeated experiments established the fact
that there is such a thing as "bla ok lightning.
or atmospheric electrical discha rHes that
are not visible, and that they are mingled
Will discharges that are visible-the old
fashioned lightning" How is II accounted
for? Mir. Larsen's own eIpla nation is as
good as any other:
The fash" he says, speaking Of the hash
that gives no Light. must have given out
light OF n wave length much shorter than
the wave lengths OF visible light. and with
a power sufficient 10 render the part OF the
plate struck by it conservative to ordinary
light. Such a fash would appear black
on a partially Illuminated background or
be Invisible"
In other words. black lightning" Il light
ming Of such short light waves that the illu-
mination is not perceived by the human eye
or by the camera, This has suggested the
thought that there may be light waves OF
suoh velocity a. TO be equally beyond the
perception OF the eve or the camera. pro-
ducinR light 90 intense that the human eye
il not only incapable Of peroeivlng Il. hu. e
ignorant Of its sziStsncs.