Evening star. [volume] (Washington, D.C.) 1854-1972, 1894-05-21
They Furnish the Most Economical
Luminant Known.
A COLD LIGHT WITHOUT WASTE
Some interesting Facts About These
Curious Insects.
PHOSPHORESCENT HES

been accomplished in the study of insects
In that branch of the animal creation Sec
rotary Langley of the Smithsonian Insti-
tuition has made perhaps the most pictur-
esque misunderstanding to the light afford
ed by firefiies
This light, Prof. Langley has discovered,
is the most economical iluminant in the
world 1t is 100 times as cheap as gas.
That Is to say, there is no waste, whereas
the waste in burning gas or lamps is more
than 80 per cent. In other words the con-
sumner pays dollar for every cents worth
OF light he gets. With electricity the waste
Is less, but still enormous. the FREELY light
expends no energy in the shape Of heat.
A Cold Light Without Waste.
So here is what might be termed a cold
hight without waste. If a process could be
invented for producing it in large quanti-
ties by artifce the discovery would be of
enormous benefit to mankind. Incidental
ly, electricity and gas would be driven out
OF use for Illuminating purposes. That the
secret will be found sooner or later is not
at all unlikely The notion formerly held
That the light was part and parcel of the
HE OF the frefly has been exploded 1t is
low believed to be simply a product of
chemical combustion.
Such being the case il ought to he nrac-
tcable 10 reproduce the phenomenon In the
laboratory or even on a large scale This
peculiar light termed ''phosphorescence."
mas received little attention from scientists
up 10 date. 1t affords attractive field for
investigation. The suppostion is that IL is
maze by the slow combustion of material
secreteo under the control of the nervous
system OF the insect. II is produced at one
four-hundrcdth of the cost of energy ex-
pended In a candle flame. Nothing is lost
IN the shape of heat, the light-giving organs
having the same temperature as other parts
OF the animal
More than 80 families of animals on land
ana In water, embracing tens of thousands
or or species. produce such phosphorescent
London, Paris and New York. The surface
or the ocean is alive with luminous crus-
taceans, tellyfishes, &C, not to mention in
Vulnerable vegetable organisms, each of
which is a tiny lantern. In the depths swim
lamp-bearing fishes. On land crawl glow
worms and electric centipedes" while in
the air firefies and lightning bugs" of
many many Kinds disport themselves All of this
light crowded into one place would hardly
affect thermometer.
Firehy of the Tropics.
The most brilliant light afforded by any
land animal is that OF the famous freely of
the tropics known the "cucujo." Thirty
eight of them yield one candle power Pho
tographs have been printed by two minute
exposure of bromide plates to their illumi-
nation. People in Cuba confine them in
paper lanterns for going about the country
at night or for indoor lighting. Sometimes
they attach one of the insects to each foot
for travelling in the dark, to serve as a
guide to the path. Also they use them as
ornaments for the dress and hair
1t is with these fireflies that Prof Langley
conducted his experiments They are beetles,
beginning life as grubs. ''Skip-jacks," or
spring-tails. they are sometimes called,
because, when placed on their backs they
clicking A
species OF the same family is found in
Florida and Texas. They have two lumi-
nous spots on the thoraX and another on the
abdomen. Damp evenings are most favor
able to the light-giving. the object of which
Is presumably to attract the sexes. The
young larvae feed largely on snails, to
which their bite is poisonous. The luminous
organs are developed before the insects
leave the eggs.
Now, a theory formerly held was that
these firefiies stored up light in the day
time for emission at night, as is done by the
so-caled luminous paint of calcium sui
phide. But 1t was found that they shone
as brightly as ever after being confined for
ten days In darkness. Some that were car
ried all the way from Cuba to Havre, in
the pitch-black hold of a vessel, were bril-
liant son their arrival A more striking dis
proof, however, was afforded by a batch of
larvae Matched in the dark, from eggs laid
in the dark in a piece of rotten wood. the
young insects being kept in darkness for the
first six months Of their lives. They shone.
Not Dependent on the Vital Principle.
Prof. Langley decided that the light did
not depend on the vital principle of the in
sect. He found that the eggs became lumi-
nous on being shaken in a glass receptacle
Then he dried the eggs and kept them in
that condition for a long time. On being
moistened they shone. The dried eggs were
powdered in a mortar, but they gave light
on being wetted. The beetles themselves,
twelve hours after being killed by electric
ity, were still luminous. So the professor
infers that nothing more than a chemical
combustion is concerned in the manufacture
of this cheapest light He thinks there is
hope that we may be able to reproduce ii
some day.
To make a light equal in brilliancy to
that of this tropical insect we must pre- duce
a temperature of 1000 degrees. The fire
fiy's lamp creates no heat that can be de-
tected by the most delicate instruments.
Its energy is entirely expended in illumina-
ton. Nature, while Offering object lessons
in the art on every hand laughs at mans
efforts to initiate her in this field. There is
a device, known as "Geissler's tube" by
which a much greater light than that of the
FREELY is made without any heat, electric
sparks being flashed through rarified gases;
but it is only plaything of the laboratory.
There are a good many kinds of firefiies
in the world. Those which give an inter-
mittent light are popularity distinguished
as lightning bugs" The glow-worm of
literature is the female of a European fire.
fly. She never acquires wings Her lumi-
nous substance is a soft yellowish grease
extending in thin layer along the inner
sides of the abdomen. A few slow-worms
exist in the United States, but they are
rare. The common frefiies of this country
have wings, females well males. The
larvae are stout bodied and grub-like, found
under stones and logs They yield some
light.
Mosquitoes Their Prey.
Mosquitoes are the favorite prey Of the
Cuban freflies. 1t is a pity that our own
species have not the same taste. The .elec-
trio centipedes." already referred to, are
black crawlers with many legs, which have
been liSened to serpents skeletons in min
iature. They move in snake-like fashion,
forward backward, leaving a bright
trail of light. However. they are most ac-
customed to appear in the daytime, W hen the
Illumination they afford is not visible A
little after sunset the lightning bugs be-
gin TO creep up spears of grass and to show
their lights. They fly irregularly upward
flashing at intervals, to a height of forty
or fifty feet.
The light produced by marine animals is
of a similar characteristic same mysterious
phosphorescence. In certain fishes of the
ocean depths the Illuminating organs are
very complex. Some of them have spots on
their sides which are regular bull s-eye lam
terms. each having lens and reflector of
its own. These are so connected with the
nervous system OF the animal that they can
be flashed turned off at will. Others of