Maryland independent. [volume] (Port Tobacco, Md.) 1874-current, 1898-10-14
COLOR PHOTOGRAPHY.
A PROCESS WHICH ACCURATELY RE.
PRODUCES NATURES HuEs.

camera and in one-fiith Of second
accurately photographing all OF the
brilliant hues Of flower garden. al
the contrasts in green of landscape,
all the wonders Of a summer sky, the
jewel upon your finger, the ribbon al
your throat, the stripes in youl
clothes, the decorations on your hat,
the bouquet on your lapel, is real
ity. This discovery and its practical
application is the work of the late
James W. McDonough Of Chicago.
He has been dead a year, but what he
discovered has been in the hands ol
friends and business associates ever
since. What be discovered is due
primarily to the dirty and nasty con.
dition of the Chicago river.
Crossing the river on the Madison
street bridge one day in 1870, Mr..
McDouough noticed on the surface Of
the murky water the colors OF the
spectrum caused BY escaping oil from
some nearby warehouse. The thought
came to him that the river would pre-.
sent a beautiful spectacle if covered
with those colors.
His second thought was as to why
that rivers surface could not be pho
tographed. From this thought grad
ually developed aud grew the process
of color photography-the first ever
given to the world-that will always
be known as McDonoughs.
Tho process that he created Is d
color photography which is purely
mechanical. The ordinary camera is
used and the negatives are produced
and developed by the usual processes,
but before exposing the negative in
the camera a transparent screen ruled
with the three primary colors is in,
terposed between the negative and
object TO be photographed.
After developing the negative a
positive plate is produced from it,
which, viewed by itself, does not differ
from the ordinary black and white
plate, but when it is laid upon view
ing screen, ruled with the primary
colors, a duplicate of the taking
screen used in the camera, the colors
in the object photographed appear.
The principle of color photography
is mixture Of colored lights on the
retiul. A Atransparent medium is ruled
in the colored lines 800 to GOO to the
inch. These lines are red, blue and
green, commonly speaking. They
are the fundamentals OF the spectrum
- the yellow of school days now being
rejected aud their mixture produces
white light. In other words, the
c ilor of each is such as to absorb the
remaining two and transmit only its
own light.
70 make picture it is necessary to
place one of these ruled screens in
immediate contact with the sensitive
surface Of the dry plate and expose
the same as in ordinary photography.
The sensitive plates must be what Is
known as isochromatic plates-that
is, sensitive to all the colors of the
spectrum.
After negative is made positive
is also made by contact printing, as
in the usual manner. This positive
is then placed over the ruled screen
and the dark lines on the positive are
made to register with the colored
line on the screen. When this is
done the picture is seen in its natural
colors.
Photographers and chemists of an
inquiring turn of mind have attempt
ed to make color photography posi-
bility since 1870. The experiments
necessary were so costly, the posi-
bility of failure 50 great, that all OF
them, with the exception of MELON
ough, surrendered at one time or an
other and announced that the camera
would never be able to repicture the
rose with all its gorgeousness in
which it hung on the parent stem.
McDonough said it could be done, and
the day before his death photographed
himself in one of the flower gardens
of Jackson park. He never lived to
see the picture completed, but ii
stands today in an office in Dearborn
street with every hue of the blossoms
surrounding him faithfully reproduced
the work of the sun and the sun
only.
The practical value OF color photog-
raphy clnnot be estimated. In the
field of the physician it will produce
a revolution. Now it is made possible
to photograph the different stages Of
gangrenous diseases, to retain the
plates, to use them for comparative
purposes, to know just what is the
shade OF color at certain stage of the
disease of the body of the patient him
self. Photography of ulcerations, OF
membranes, of skin affections, is all
possible aud so valuable that the nse
of the process is almost certain to be
demanded at once by the medical pro-
fession.
In the detection and prevention Of
crime the color photograph promises
to become an important adjunct TO
the Bertillon system. Rogues may
now be photographed as to the color
of their hair, of their eyes, the shade
OF sears upon them, redness OF skin
and thousand aud one minutie
hitherto unusable by detectives.
In the process of taking the picture
of a person, the color of his hat, of
his necktie, of his clothes, of his shirt
front, Of his jewelry, is all accurately
taken and forever kept.
The McDonough patents, which are
of the broadest kind, have been grant
ed by the United States, England,
France, Belgium, Austria aud Ger
many.
The patent Office thought SO highly
of McDonough's work that at the
Omaha exposition it has made an ex-
hibit of many pictures by his process,
the government standing the expense
of the exhibit.
Mineral Wealth abont Santfago