The citizen. (Frederick City, Md.) 1895-1923, 1899-07-14

ed such various interpretations,
DR.. Gustave lie Bon has been
striving to illuminate the subject.
He showed at first that dark bod
les may be photographed in the
dark by the invisible light alb
sorbed during short exposure to
sunlight, and has since proven
that this invisible light may be
refracted and polarized, has a
SPECTRUM identical with sunlight,
but more extended, and preserves
its Photographic power for more
than a year. He has finally been
aided in his investigations 10y the
discovery of reagent 5000
times more sensitive than he
Photographic plate. This is
phoSphoreScent >ulphide of zine,
which is converted into a trans
lucent or opaque screen by MKT.
ure with varniSh. Exposed to
daylight it becomes self-luminous.
but when the visible rays are ill
tered nom daylight those remain.
ing actually eXtiuguiSh the phoS-
phoreSccncc. These eNtinguish
ing rays are those that pass
through so-callcd Opaque bodies.
Using an ordinary lamp entirely
enclosed in black paper as a
source of light, the outlines OF
Intervening objects may be pro-
duced ON the screen. but remain
visible in the darkness only a few
moments. Light penetrating an
inch slab of marble gives images
in from } to 80 seconds, through
% inch sheet of ebonite in 10
seconds. only lampblack being
found quite Opaque to the dark
rays.
The Leonid stream of meteor.
ties, we have often been told. is
a ring of PARTICLES moving about
the sun in about 334 years, and
crossed by the earth'S orbit at
point We now reach on or about
November 18th. The particles
are mostly aggregated at one
spot IN the ring, SO that the mum
Der attracted to the earth on
every 33rd annual crossing is
much greater than the average.
Recent calculations show that
this year. the year of the expect
ed great shower, we shall rGch
the ring about one day after the
regular time, on account chiefly
of the peturbing influence of Ju-
piter and Saturn, and that the
middle of the shower will proba.
bly, be on November Is. at 6 a.
m, Greenwich time.
The claims made for new oil
engine, lately tested on the
Thames seem to entitle this motor
to more than ordinary attention.
1t is the invention of Mr.. II. c.
Bryant, of ChiSwick, who has dis
covered that when ordinary heavy
petroleum oil of high flash point
Is used to charge a column of air
and this air is compressed with a
column Of pure air, ignition takes
place at low temperature and
compression, and the explosion is
much slower than usual. eXpan-
sion continuing to the end of the
piston's stroke. The motor built
on this theory has the ordinary
water jacketed cylinder and pis-
ton, with a novel form of combus-
ton chamber The piston is
started by placing a lamp under
tl5 mixing chamber for few
moments, after which the engine
becomes Self-fring. So low is the
temperature that the water jacket
is really unnecessary. a single
cylinder engine developing three
brake horse power when running
at $50 revolutions is only a foot
square on the floor and three
feet high, and weighs somewhat
less than 800 pounds. The com
preston does not exceed 60
pounds per square inch, the
greatest working pressure reach
ing 800 pounds.
Like many another long-retain-
ed NJ ton, the idea that dogs
perspire in an unusual way,
proves to have no foundation in
fact. Replying to an inquiry,
MIR. S. @. Shattuck, of the Royal
College of Surgeons, states that
dogs cannot sweat by the tongue,
as the only glands in the dogs
tongue are in the poSterior part,
and, these have a mucuS secret
ing structure. The dogs skin,
moreover, is abundantly provid
ed with glands like those produc-
ing sweat in man.
A novel artificial limb, of En-
glish origin, is intended for am
putatiOns below the knee;joint.
The end of the amputated limb