Evening star. [volume] (Washington, D.C.) 1854-1972, 1899-12-02

offer of 6,O0OOO0 francs for the Paris ex-
position, entered into an iren-clad contract
not to show the distance seer anywhere
before that date.
There is no doubt at the present day that
Szczepaniks invention has solved the long
dreamed-of problem of sght-at-a-distance,
over wires, just as the telephone trans
mits sound. Photographs are shown that
have been taken In darkened room from
a camera situated forty miles away At
the exposition, where the telectroscope-as
Is is scientifically named-will be exhibited
in a building capable of seating 5000 peo-
pie, the views, In full color as in move
ment, will be thrown on a screen as in the
case of an ordinary magic lantern. There
they will show, they say, the moving life
of Piccadilly Circus in full London, the
rival of a transatlantic steamer at Brest or
Havre the finish of a Longchamps horse
race and. as curious as anything, a birds
eye view of Paris, taken from a balloon
actually in the air. The best seats at this
show will be 20 francs-S4-each
The Underlying Principle.
The principle of the telectroscope denends
upon the fact that any image produced
upon the retina of the eye is only the
| blending together of an infinite number of
points projected separately from the object
seen by separate rays of light 1t is not
necessary that all these points reach the
eye at exactly the same moment: the vision
will still be perfect, though some come a
fraction of a second later than others or
walls, provided they be short enough The
persistence of vision of the eve will
bring them together in a complete picture
just as it makes a circle of fire out of a
glowing match end when 1t is moved swift
ly round and round.
Now SZcZepanik has found way of
separating any image that may be formed
by an ordinary Photographic lens into its
component luminous points, of transmitting
these points separately-but with enormous
rapidity-over wires and of letting the eye
reconstitute them at the other end into the
original picture.
How 1t Works.
1t therefore seems that the perfected tel
ectroscope works something after this
fashion. Two vibrating mirrors do the
work of resolving the image into points
and project them upon a selenium disk
Selenum is rare element, something like
sulphur. which has the singular property
of Transforming waves of light into waves
of electricity; SO that if rays of light be
thrown upon a selenium disk from which
wires extend. It will be found on closing
the circuit, that current is set up in the
wires Furthermore-and more important
these rays of light. differing in color and in
tensty. produce currents which also differ
in intensity, each particular ray having its
corresponding current, and no two of them
alike.
The mirrors are metal plates fixed on
sounding boxes. and are kept in continued
Vlbrd ton long as electric bell a
certain pitch is sounded somewhere in the
apparatus. Furthermore, as these metal
plates and their sounding boxes are tuned
to the pitch of the electric bell the two
mirrors must vibrate at uniform rate
5000 or 1000 times a second. And in the
same way the two mirrors in the receiver
must vibrate in unison with the far-away
other pair.
4 Marvellous story.
How these mirrorS-Vibrat ting say, 1000
tiny points of light and transmit them-at
the rate of 1000 to the seconds IA mar
Vicious story. Though mirrors, they are
blackened so that they reflect only one line
ed CHI as fine as the edge of a knife blade
In the first blackered plate the mirror line
runs CrossWise in the second it runs length
wise; so that while the first, vibrating, re-
fleets successive linrS-as fine as the edge
of a knife blade-on the second the latter
reflects only single points of these lines
upon the selenium cell-fOr, of course, the
intersection Of two lines must be a point.
This tells the St0ry-the selenium disk
does all the rest. Transforming the wages
of light into waves Of electricity, it gives
them to the wires for transmission. At the
other end the series of electric impulses
acting on two steel plates-or 'lipS"-cause
them to open and close so that the band of
light between them constantly changes in
intensity. The two mirrors in the receiver,
being arranged Ike the two in the trans
s.
and the same narrHw lines of reflection
pick out single points from each band of
light. and project these points with meal
Culabe rapidity upon a grOund-glass plate.
on which the Eye blends them together in a
perfect picture.
The Great Telescope.
The greatest scientific rival of the dis
tance-seer,' the great telescope progresses
in its making. News now comes to Parisians
that the glasses are all successfully ground.
Strolling through the exposition grounds
the other day, l stumbled on the masonry
work. already well in hand. on which the
monster will repose its length. For IT is to
be remembered that the grand siderostat
VIII be far too long and heavy to be held
up and pointed at the moon and stars The
length of the steel tube is to be 80 feet
with diameter of five feet AS It cannot
be pointed at the sky. the moon and stars
Will be caught by q giant mirror and thrown
into it. When it is known that this mirror
with Its movable surroundings, will alone
weigh 10000 pounds. and will have to be
operated In a pond of quicksilver some idea
or the greatness of the underta king will
have been gained. The crowns and fiints
Will cost 100000 francs, and the entire ex-
pense Will run into the millions. The funds
pelhg furnished by company that has Sc
cured the right to unite many kindred OBJ
Jects OF interest IN an imposing Palais de
Ioptque, there can be no doubt that this
monopoly Will put a high price on its Won
ueiH' w no Woulu not pay dollar to see
on screen-a lunar landscape at the dis
lance or. say, ten miles? Some say the
Grande Lunette viii bring the moon so close
TO US that we may watch the evolutions of
an army corps or d fleet upon it's surface
or even, the goings and comngs of an an
lmal the size of an elephant! During the
total eclipse of the sun on May -. 1900
the hrst visible in Paris since 1S93-admis-
slohs TO the amphitheater of the great tel
eScope VIII run up to s. each. Should the
canals or Mars be discovered to be really
the work of intelligent creatures there is
no tellmg to what price the competition of
human curiosity may send up the admis-
II Is the moon and the planet Mars that
VIII be most observed through the Grande
Lunette by the visitors to the exposition
OF 1890. All through the summer the
grounds Will be almost as bright and quite
as gay by night in the daytime. The
great guess at the present moment is what
shall we see?
1t IS declared that the moon will give at
the focus of this greatest of all telescopes
an image Of 23.4 inches in diameter Up
TO the present time the greatest enlarge
ments of focal images have been 1900
times. With the Grande Lunette they may
pc, under certain circumstances enlarged
as much as 10000 times. This will be as
n Of