The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1898-04-03

] from loot TO head, and crOSSWlSe ana
obliquely, and in every other direction
! possible, as the glass turned or oScIl-
lated about. This constantly changing
reflection of the man would be passed
on TO the other mirror, which hangs
just above the first. This second mir
ror is also kept moving about, or
changing the plane of its reflection. The
moving reflection of the man in the nrst
mirror was, as has been stated, broken
UP into lines, and when Ii struck the
CROSSINGS of the second mirror il neceS-
sariiy became dots, so that constantly
changing series OF dots OF light, SHOW
ing the reflection of the man outside, is
now projected into the upper part of
the box or transmitter. OF course, all
the colors OF his costume are reflected.
as well as the shape of his body.
TURNING COLORS INTO ELECTRIC
CURRENTS.
In the top of the box, behind small
partition, Is a resistance cell or plate
made OF selenium. Selenium is a very
sensitive substance. II current or
electricity is sent through 1t, il will re-
sist the passage of the current, and cut
1t down, according to the temperature
and the light in which il may happen TO
be. For instance, if an electric current
is passing through q piece of Selenlum
while a red light is shining on it, the
quantity of current which will finally
get through will be very different from
what 1T would be If the selenium were
to be placed in the blue light. This very
sensitive characteristic OF selenium is
taken advantage of TO transmit pic
lures by wire. The dots of light, which
really form the image TO be transmit
ted, are allowed to play through a mar
row slit in the partition against the
selenium cell in the top or the box.
The selenium is part of the circuit or
wire through which the picture is to be
transmitted. This circuit may, for all
practical purposes, be hundreds of
miles long. An electric current is made
to flow through it, and, consequently,
through the selenium. Now, the refiec-
ton of the man outside the box, with
all the colorS OF his costume, is being
projected constantly against the Sc
ienlum in the top OF the box, and this
rapid interchange of color is causing
the electric current which flows through
the selenium to vary constantly in
strength as the different colors in the
reflection affect the resistance of the
selenium. 1t therefore follows that an
electric current is easily obtained, the
strength of which depends entirely on
the nature of the color which is pro-
jected against the Selenium. The
TRANSMISSION of colors, or, at least, the
transmission of their equivalent in cleo
trio currents, is what has been accom-
plished.
Having accomplished the feat of
sending colors, or their equivalents, by
telegraph, ii now became necessary to
separate the various parts or intensitieS
of this varying current, and TO resolve
them into colors again at the other end
of the line. In short, just as the selen-
ium was able to change colors into their
equivalents in current, popularity speak
ing, so must some method be found OF
changing these currents back into their
equivalent colors. 1t was done in the
following manner: The line which
transmitted all of these varying cur
rents ended at the. receiver in a coil
which formed an electromagnetic. When
the selenium allowed heavy currents to
flow over the wire, the electromagnetic
became very powerful When weak
currents flowed over the lice, the cleo
tro-magnet became weak. In front of
the core of this magnet a large prism
was placed. 1t hung in a horizontal
position, and moved on a pivot. At
tached to it was a piece of soft iron.
This iron was naturally affected by the
magnet, and caused the prism to move
backward or forward, as strong or
weak currents flowed from the selen-
ium at the other end of the line.
HOW THE SPECTRUM IS UTILIZED.
1t is. we'll known fact that if
strong beam of light is projected
through a prism the latter will separ-
ate the various rays of that light and
spread them out in the form of spec
trum, or band of colored light All of
the reds in the beam will be shown at
one end of the spectrum, all of the
blues at the other end, with the inter-
mediate colors between. In the re-
ceiver of Szczepanik's apparatus a
powerful incandescent lamp was placed
just back OF the prism, which moved on
a pivot. Naturally, the prism took up
the beam Of electric light and separated
it into a spectrum, or band of light,
with the reds at one end of the band
and the blues at the other end. This
band of variously-colored light shone
against a partition in the upper part
of the receiving apparatus. There was
a narrow slit in this partition. cut so
that only one color of the band of
light could shine through at a time.
BY moving the prism backward and
forward it was easy to start at one end
of the colored beam of light and make
first the red lights shine through. and
so on along the beam until the blue or
violets were reached.
Now. when the selenium in the first
apparatus was affected by red light,
and a current corresponding in strength
to red was, therefore, allowed to flow
through the wire, the second apparatus
was so adjusted that the electro-mag-
net would turn the prism around. SO
that only red light would shine through
the slit mentioned above. When a
current corresponding in strength to
blue was transmitted, the magnet
turned the prism around until only
blue light was allowed to shine through
the slit. So that, if the man who stood
in front of the transmitter wore blue
necl1tie, and the blue of that tie was
by the mirrors against the Sc
lenium, the latter would Immediately