The Republican. [volume] (Oakland, Md.) 1877-current, 1880-03-27

determine the proper composition and
arrangement of the mirror and specu-
lum. For the former he had finally Sc
lected an amalgam of selenium and
iodide of silver, and for the latter a
compound of selenium and chromium.
The peculiar sensitiveness of iodide of
silver and chromium to light has long
been known, and their practical use in
photography suggested their applica-
ton in the diaphote. 1t was found,
however, after many experiments that
their. action must be so modified that
each ray of light should influence the
electric current proportionally to its
position in the solar spectrum, and
selenium was ascertained to be best
adapted to this purpose. At first a
small mirror was employed with only a
single wire, but the images reproduced
in the speculum were indistinct and
confused, so that it became necessary
to make the mirror of 8 number of
small pieces, each about one third of a
square inch in area, and having a small
wire attached. In the diaphote exhib-
tied by DR.. Licks to the Club the mirror
was six inches by four and had seventy
two fine wires, which are gathered to-
gether into one about foot back of
the frame, the whole then being finely
wrapped with an insulating covering,
and on reaching the receiving specu-
lum, each little wire was connected TO
division similarly placed as in the
mirror. From a common galvanic bat
terry wires also ran to each diaphotic
plate, and thus a circuit was formed
which could be closed or not at pleas
ure. The theoretical action of the in
strument appears now to be in the fol-
lowing: The waves of light from an
object are conducted through an ordi-
nary camera, so that they fall on certain
of the divisions of the mirror when the
electric current is closed. The light
and accompanying heat produce mo-
mentary chemical changes in the ANAL
gam of the mirror, which modify the
electric current and cause similar
changes in the corresponding partitions
of the remote speculum, thus reproduce
ing similar image, which by sec
ond camera may be readily seen by the
eye or thrown on a screen. DR.. Licks
explained how the proportions of seleni-
um in the mirror and speculum should
be scientifically adjusted to the size of
the divisions and the resistance of the
electric circuit, so as to avoid any
blending of the proportions of the re-
produced image. This, he said, had
been the problem which had caused
him the most difficulty, and which at
one time had seemed almost insur-
mountable.
At the close of the paper an illustra-
ton was given of the powers of the in
strument. The mirror of the diaphote,
in charge of a committee of three, was
taken to room in the lower part of the
building and the connecting wires laid
through the halls and stairways to the
speculum on the lecturers platform.
Before the mirror the committee held
in succession various objects, illu-
minating each by the light of
a burning magnesium wire, since the
rays from gas are deficient in actinic
power, and simultaneously on the spec
ulum appeared the secondary images,
which, for exhibition to the audience,
were thrown on a screen considerably
magniiied. An apple, pen-knife and
trade-dollar were the first objects
shown; on the latter the outlines of the
goddess of liberty were recognized, and
the date 1873 was plainly legible. A
watch was held five minutes before the
mirror, and the audience could plainly
perceive the motion of the minute hand
on the screen, but the movement of the
second hand was not satisfactorily seen,
although Professor Kannich, by looking
into the camera, thought that it was
there quite perceptible. An ink bottle,
a flower and part of a theater hand
bill were also shown, and when the
head of little kitten appeared on the
screen the club testified its satisfaction
by the most hearty applause. After
the close of the experiments the sclen-
lists extended their congratulations to
DIR. Licks, and the president made a
few remarks on the probable scientific
and industrial applications of the dia-
photo in the future. With the tele-
phone and the diaphote it might yet be
possible for friends, separated by the
wide Atlantic, to hear and see each
other at the same time, to talk, as it
were, face to face. In connection with
the interlocking switch system it might
be used to enable signal-men of the CEN
trail office to see hundreds of miles of
railroad track at once, thus lessening
the liability to accident. In connection
with photolithography it might be so
employed that the great English dailies
could be printed in New York few
hours after their appearance in Lon
demonstrating (Pa.J Eagle.