Milford chronicle., 1908-12-25
Recent Discoveries Made Through the
Use Of the Camera.

RECENT glsCoNNTloe mua9 AW~NsH ~
Use Of the Camera.
Remarkable studies of the nature Of
lightning have been made by a gifted
Danish-American experimSnter. under
the auspices OF the Smithsonian insti-
tuition. 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 eIistencs
OF black or invisible lightning has been
ascertalned. The genius who has taken
lightning for his study is Alexander
Larsen, who came to this country from
Denmark a 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 a common hand camera,
and suggesting that if a camera were
so geared as to be moved during light
ming flashes the duration of the fash
might he determined and its nature
made clearer. The institution became
interested IN the ingenious immigrants
work and granted him small sum
with which to 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. 1t was soon discov-
cred that what is called a fash OF
lightning is in reality a succession Of
flashes, following one another with al
most incOnceiyable swiftness and de-
celving the eye with an appearance OF
oneness. Mr.. Larsen counted upon his
sensitive plates as many as forty
flashes In a single streak OF lightning
and is convinced that in the forty were
scores Of swifter flashes which eludsd
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 $1,000 Of a second apart. The
was made by calculating
the width Of the film and the move
ment OF each camera.
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,
bur the camera did not catch any light.
Repeated experiments established the
fact that there is such a thing as
''back" lightning, or atmospheric cleo
trical discharges that are not visible,
and that they are mingled with dis
that are visible-the old fash
oned lightning. How is it accounted
for? Mr.. Larsen's own explanation is
as good as any other:
"The fash" he says, speaking of the
fash that gives no light, must have
given out light of a wave length much |
shorter than the wave lengths Of visi-
Bile light and with a power sufficient to
render the part of the plate struck by |
It nonsensitlye TO ordinary light Such |
a fash would appear black on partial |
ly Illuminated background or be in
visible"
In other words. "black lightning" is
lightning 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 We
Iocity as to be equally beyond the per
ceptlOn of the eye or the camera, pro-
tuclng light so intense that the human
eye is not only incapable Of percelving
t, but is ignorant Of its existence
Washington Post