Evening star. [volume] (Washington, D.C.) 1854-1972, 1911-03-26
SUNDAY MAGAZINE FOR MARCH
QUEER FACTS CONCERNING LIGHT

communities which burn the most OF gas or
oil or electricity that also seem addicted to
the use of the oldtime illuminant. Take
mines, for example. Where electricity is to
be found as a lighting as well as an operating
power, the tallow candle seems to be burned
with almost lavish prodigality.
The complaints will be remembered that
have been handed down verbally and in
print, that the introduction of machinery
would deprive no end of men of jobs. Print
ers can remember when the introduction of
typesetting machines seemed to threaten
their very existence. Time has shown these
fears to be futile. The demand for the ser
vices of such men ever increases. Men are
needed to run the machinery. Facility of
production seems only to increase the needs
for commodities.
But how does this explain the use of the
tallow dip alongside the most modern Of
illuminants? In few places is found the
horse car, for instance, in competition with
the electric car. The answer is simple
enough. The better system of lighting to
which we are now accustomed has rendered
us impatient of gloom. Where we cannot
take our incandescent bulb or gasjet, there
we insist upon having some illuminant, and
the ever-handy tallow candle answers the
purpose. Gas or the electric lamp does not
quite dispe1 the shadow in that particular
corner of the hall; hence the tallow dip.
Light and Energy
STATISTICS showing the enormous waste
~ of energy involved in the production of
artificial light are always interesting, if for
no other reason than that they must con-
tinua1ly stimulate inventors in the search for
better methods.
Sir James Dewar presented these figures
before the Royal Institution of Great Brit
ain: In an ordinary candle the total quanti-
ty of energy transformed into light is only
two per cent. Oil and gas lamps are not
more economical. The incandescent electric
lamp Utilities three per cent. of the energy
expended, the arc light ten per cent, and
the magnesium light fifteen per cent. Then
comes the glow worm and mocks us with its
ninety per cent. of expended energy turned
into light
Light from Sugar
THIS phenomenon, the cause of which has
not yet been satisfactorily explained,
may be observed when disks of loaf sugar are
mounted on lathe and rapidly rotated while
a hammer plays lightly against them. An
almost continuous radiation of light may be
thus produced from the sugar. 1t has been
shown that the light does not arise from
heating of the sugar, and it is believed to be
sugar crystals. The act of capitalization is
known to be sometimes accompanied by
flashes of light. The practical bearing of
these experiments is on the question of the
possibility of obtaining artificial light by
methods as yet untried.
Automatic Lamp Lighting
THE property of selenium to vary its cleo
trio resistance in accordance with the
intensity of the light falling on it has led to
the invention of an apparatus for the auto
matte lighting and extinguishing of lamps.
A selenium cell is so arranged in circuit
that it actuates a switch in one direction
when daylight falls on it and in the opposite
direction when darkness ensues. Thus an
electric lamp or a gaslamp provided with
small igniting flame, may be caused to light
itself on the approach of night and to turn
itself out at daybreak. A similar arrange
ment may be used for automatically turn
ing off the stopcock when gaslight is acct
dentally extinguished.
Light and Perfumes
A GARDEN full of flowers is more fragrant
\ when Swallowed by cloud than when
bathed in sunshine; at least that is the con-
clusion to which recent experiments of a
E~o~o1, 1aod IJo occarfc that If