Evening star. [volume] (Washington, D.C.) 1854-1972, 1907-06-03
LIGHTNING FLASHES CAUGHT
DEMONSTRATION
BY ALEXANDER LARSEN.
Cameras Placed Upon a Revolving
Table So as to Photograph Electric
Rushes-Some Found Dark.

Smithsonian grants to night school stu
dent are not common but that is what has
happened In the case of Alexander Larsen,
Danish immigrant, who has made a spe-
cial report on the makeup Of lightning
flashes as the result of small grant that
was made him for scientific apparatus
Mr.. Larsen came to this country only a
few years ago, and all his study of chem
istry, photography and electricity has been
picked up while attending night school. He
made some remarkable lightning pictures
with an old hand camera, and. presenting
the subject to the Smithsonian Institution.
explained what he thought he could do in
the way of measuring and studying lightning
flashes if he had little better apparatus
The officials were Interested in his work
and small sum was given to him with
which to continue.
Larsen rugged up revolving table. upon
which he placed cameras in such position
as to catch lightning flashes at various
phases. 1t was soon discovered that what
is called a flash of lightning is in reality
succession of flashes. following one another
with almost inconceivable swiftness, and
deceiVing the eye with an appearance of
oneness. Mr.. Larsen counted upon his SEN
sitlve plates as many as forty flashes in a
single flash of lightning, and is convinced
that in the forty We're 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 two one-thou-
sandths of second apart The measure
ment was made by calculating the width
of the film and the movement of each cam
era.
"Black Lightning"
Many obscure things were noted 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 thing as "bla ok" light
ming, or atmospheric electrical discharges
that are not visible, and that they are min
gled with discharges that are visible-the
old-fashioned lightning" How is it ac-
counted for? Mr.. Larsen's own explanation
IS as good as any other:
THE FASH Sc says, speaking of the flash
that gives no light, must have given out
light of a wave length much shorter than
the wave lengths of visible light and with
power sufficient to render the part of the
plate struck by it nonsensitive to ordinary
light Such a flash would appear black on
a partially illuminated background, or be
invisible"
Too Quick for the Camera.
In other words. BLACK lightning" is light
ming of such short light-waves that the
Illumination is not perceived by the human
eye or by the camera. This has suggested
the thought that there may be light-waves
of such velocity as to be equally beyond the
perception of the eye or the camera. pro-
ducing light intense that the human
eye is not only incapable of perceiving it,
but is ignorant of its existence.
Some of the scientists of the Smithsonian
Institution. bordering upon Larsens dis
coveries, wondering whether it may not
be possible to discover that the abysses of
the universe are not immersed in darkness
between planet and planet they seem to
be, but are really bathed in light of such in
tense quality as to be totally imperceptible
TO human beings.