Evening star. [volume] (Washington, D.C.) 1854-1972, 1893-11-25

negatives-one reproducing the reds of the
wafer color, another the DIueS ana the third
the yeiiowS. Prlnts are made from these on
blcnromauZea selaune, anu from the prints,
by the process commonly used IN pnoto-
engraving, metal cuts are produced. one
cut, being linked with REQ INK ana applied
to sheet OF blank paper, puts on ali the
reds required TOR the picture; another cut
adds the blues, and the Thru cut contrib
utes the yellowS.
The white lines made by the grating
are almost microscopically fine, anu 90 not
snow, except on close scrutiny with a mag
nlfylnS glass. In each of the three cuts
they run at different angle, SO that in the
mai picture they cross each other In
patchwork pattern. Where one color is
printed over another it forms combina-
ton with it. Thus blue and yellow make
green. and the primary colors-yellow, red
and blue-produce in this way every grada-
ton of tint The effect is wonderful.
In fact, the reproduction of a water color
painting obtained in this fashion is perfect
almost beyond belief. 1t gives all the
brightness ana deicacy of the original, with
even the peculiar and characteristic wash
effect. But the process is applicable in all
sorts of other ways. 1t will copy with me-
chanlcal faithfulness and vivid hues the in
tricate pattern of a Turkish rug. Land
scapes from nature will be rendered by it
before long, the inventor claims, and per-
haps even portraits eventually.
Another American has perfected a pro-
cess of Photographic printing in colors some
"Hdl 10 lndt devised Dy the New
York photographer above mentioned, though
modified in its application. He, too, uti-
Lies the glass screens for red, blue and yell
low lights; but he prints the colors sepa-
rately upon translucent filmS-the reds on
one film, the blues on a second and the yell
low on third. Then he superposes the
Minis one upon another, and places them
together between two sheets of glass; To
the eye, looking at the light through the
glasses thus Joined, with the films between
them, all the original effects of colors and
color combinations are reproduced. Thus
the appearance of thin slices of rock and
chemical crystallzations. as observed under
the microscope with polarized light, is most
beautifully preserved.
In quite different manner these films are
employed to produce extraordinary effects.
PlctureS-to Illustrate lectures, for example
are projected upon a screen by means ora
magic lantern with three lenses The ar
rangement is such that behind one lens is
the yellow film, behind another the blue, and
behind the third the red. BY simple me-
chanical device all three lenses are made to
focus so that q single image is cast upon the
white sheet, the colors combining and pro-
ducing most gorgeous and realistic effects.
Color photography will be a great help in
the work of making acknowledgements of
sections of rock. This business engages a
good deal of attention at the Office of the
geological survey in Washington. The OBJ
ject of it is to find out the mineral elements
of which various rocks are composed.
For this purpose small piece of rock is
GOWN until IL is a transparent MIN
so thin that one can read through IL. 1t is
then put into Photographic apparatus, an
important part of which Is a microscope
The instrument is SO arranged that a ray
of light passes through a prism of Iceland
spar, which has the property of "po!ariz-
ing light. The ray passes on through the
film of rock, which is stuck upon sheet
of glass; and beyond through the micro
scope. the other end of which is fitted into a
camera. Thus a very much ma gnified i'm
age of the rock section is thrown upon the
sensitive plate inside the camera, and an
enormously enlarged picture of it is made
The picture is merely in black and white
but the image produced on the ground glass
at the back of the camera is In all sorts
of beautiful colors, each mineral element of
which the rock is composed being made
by the refracting effect of the polarized
light to take on hue of its own, so that
even the least bit of ordinary cobblestone
is patchwork of lovely tints. AS 1t is, the
photograph has to be tinted with water
colors, copied after the image on the ground
glass; but. if the colors could be directly
reproduced, the object would be obtained
most simply and with a superior perfection
Professional photographers, as rule
take little interest in color photography
They care for nothing that is speculative
being concerned merely with the business
of the present. That is the reason why So
called amateurs have already got far past
them in the purely artistic developments of
the craft.