The San Francisco call., 1907-06-10


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 pho
tographs Of lightning which he had
taken with common hand camera, and
suggesting that II a camera were so
geared as to be moved during lightning
flashes the duration Of the flash might
be determined and its nature made
clearer. The institution became inter-
ested in the ingenious Immigrants
work and granted him a small sum with
which to pursue his studies with a bet
ter equipment.
Larsen rigEed up a 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, fol-
lowing one another with inconceivable
swiftness and deceiving the eye with
an appearance Of oneness. Larsen
counted upon his sensitive plates as
many as 40 flashes In a single fash of
lightning and was convinced that in
the 40 were scores of swifter flashes
which eluded the camera. Measure
ments were taken of the time elapsing
between the flashes or rushes that
could be seen on the negative. It was
found that some of the flashes were
2-100o of a second apart. The meas
urement was made by calculating the
width Of the film and the movement 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
tnere. Just the same as In the flashes.
put the camera did not catch any light
Repeated experiments established the
fact that there was such a thing as
Diack lightning. or atmospheric cleo
trfcal discharges not visible, and that
they mingle with discharges that are
visiole-the old fashioned lightning"
How 1t fs accounted for? Larsens own
explanation 10 as good as any other:
The FASH" he says, speaking of tbs
fash that gives no light. must have
given out light OF a wave length much
snorter than the wave lengths of visible
light and with power sufficient To
render the part of the plate struck by
1t nonsensitive to ordinary ligiu. Such
hash would appear black on a par
tally illuminated background or be in
visible"
LIGHT WAVES ARE SHORT
In other words, black lightning" is
iightnins 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 az to
Dc equally beyond the perception of
the eye or the camera, producing light
so intense that the human eye is not
only incapable Of percefving it. but Is
ignorant OF Its existence. Some of the
scientists OF the Smithsonian Institu-
tion.' pondering upon Larsen's discov-
cries, are wondering whether it may
not be possible to discover that the
abysses of the universe are not Inn
mersed in darkness between planet and
planet, as they seem to be, but are
really bathed In light of such intense
quality as to be totally imperceptible
to human beings.
Larsen Is conducting experiments In
another interesting field, that of f1uor-
esccnce. AS some substances are so
heavily charged with phosphorus az to
give out light, SO there are many sub
stances. mineral. chemical. gaseous and
liquid, which give out light waves of
various colors when subjected to the
action Of light or electricity. The
nuorescence Of radium, for example, is
notable under varying charges of
electricity and light Another sub
stance with particular fuorescent prop
critics II kunzite. the new precious
mineral discovered in San Diego coun-
ty. California This stone gives out a
beautiful lilac colored light for hours
after being subjected to the x ray
The national museum has furnished
thousands Of specimens Of minerals to
Larsen to be used In his experiments.
and It IL said that his researches have
resulted In important discoveries In
this highly technical held Of study.