New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1894-12-10
SCIENCE AND MECHANICS.
PoLYCHROMATIC PHOTOGRAPHY.

| POI,YCHROMATIC PHOTOGRAPHY.
MAKING ONE NEGATIVE ANSWER FOR THREE
| IN COLOR COMPOSITES.
One OF the bes-known systems OF repro"'o.o
OF proper color effects with Photography iet
| the use OF three negatives of the same suoJeo'
each being taken through TRANSPARENT se 49,
| OF n different color from that used with the o'ne'''
| and then when positves have been printed from
| the plates IT is further necessary to use these
latter pictures and new set or screen u p''
n composite that Is either viewed py ''''s'
observer looking into an instrument ca''eu @
polychromoscope or as projected upon M
surface by means OF triple magic lantern me
fret NJ these two mans was developed by Fred
er,ck f. Ives OF Philadelphia. and the latter
was shown in this city last winter by i'ooe 80
| Gray a Beekman-st. lensmakcr professor 'o'y,
OF Dublin according to THE Photographic LINES
has recently announced new apphcat'oh VI '"e
underlying principle which enables MIN " p
duce the same effect with one plate ana one
screen.
The essential feature of the new method Is tha'
/ the three primary colors are used OH d '''e
screen in n series OF very fine lines OF Transparent
pigment Xix aniline dyes, mixed Win SUI" 49,
OF uou,d geIatne These are ruled with maine
matical precision so as to be of the same "i'.n
and with perfect regularity mere S
be at least 90 to the inch OF course, the io'e '
better The three colors. orangered' gree" an"
blue-vioet are repeated in the same succeSsio"'
and adjacent lines are contiguous 80 that no
white light can penetrate between them l"'S
screen is then laid upon the Photographic pa"
with the pigment close against the SENSITIVE "'
\ better contact be secured II thc glass; p'"
used for a screen first be ground ana po"S"e"
1t is also important that the film shall DE fnaue
| nute sensitive 10 red light b. the use OF proper
| chemicals Now when exposure has bceh h'a"c
| In a camera through this screen. inc ola''s. ''
| lines allow the red parts OF the original SupJc',
to impress themselves strongly on the plate ana
tt,f pln
, combination with other hues, viii register ,,'i'
selves in proportion to their intensity. sun "
| Is only rcd~ that operate through the req ""'S'
The same thing is done by the green's ana S"au'
OF green by he green lines. ana ior the
hv the violetblue lines When the Photographic
plate is "dcveoped by bath In proper chefica' So
lutions. 1T IS In black and white. or ra'her IS
| onaouc and clear according to the amount OF hsh'
| affecting IL at different points, put the icS"i''"e
picture Is rendered In fine. parallel lines ea'" ca
| hibiting countless variations In density a'o"s ''
| length From this plate, as from any other mega
| two nositiyc would usually be taken, but the
latter must for this work be printed not on paper
! but on glass so as to be transparent II Il now
necessary to lay this positive color screen
/ Ike that used In the camern. with the req HheS
| covering II ose parts OF the image taken throush
red and tn. other lines showing a similar con-
! foruIty The Two sheets OF glasss1n such juNth-
| position being held so that the observer can loon
| through them toward any ordinary source "a
| light, a window lamp OF eas-burner. ne gets
result Identical with that produced IN the pho'"-
/ chromoscope IN Mr. Grays projections except
| that the picture is not magnihed. and the colors
! ar. not blended quite thoroughly Upon close
| examination. can SEQ that adjacent INES haNr
different hucs But ~ the observer VIII stand on
| Al such a distance ~ would make WOOD cngi"V-
! ine look Xix. n half-tone photograph The eye VIII
/ he sufficiently deceived And n the primary
colors be- pure and ~, the tcslrcd intensity not
only viii they be- faithfully reproduced Themselves
where they should but they will also combine In
/ The proper proportions to render the secondary
/ coors yellow and purple. and the more complex
mixtures. olive brown. ana 30 on VII" COM
| iaraiive adelty
II is ~ the utmost importance that the right
shades Of color De used IN preparing The screens.
and their selection is vastly more d!iicHlt task
/ than one might suppose. who has not investigated
/ this subject Sometimes It f. necessary To use
| slightly different shades Tor viewing from those
| employed In phoiographlng. although In both scts
the same general colors are requisite. and occupy
the same places. IT some pictures II r. not neces-
! sary TO make positive print The negative VIII
/ oc,arlonany answer Professor Jolly says. too.
that Instead Of using separate piece OF glass for
/ , screen. one may draw the colorrd lines right on
! the sensitive plate. and photograph right through
/ them II the colors De- mixed wiki easily
/ soluble substance. Ike gum arabic. they may be-
/ washed OF during development" but n no pos
I tl.c ls Co De- printed from th" plate. and y the
B shades az color AZ. suitable for viewing. then
I cost ~ yaruisa may. with advantage. be- put on.
+ thus fixing The eolora la place. IN such a case.
though. the color must be- put first ON the glass.
/ then the ,arnish AMI the senst.ve emulsion last.
20 mat the developing solution may act OF the
MIN. several other trlHng notifications Of this
I general method nave been proposed. which need
I not he mcuton"I her"
Professor JoIy's plan involves distinct addition
10 the PREPARATORY Labor Of poly chFom'uc phot"s-
/ r,phy PronsLl, M.ssrs. Ives ami Gray and their
Il Mod 10 RE conn. % ont fD
: with their thrccfolI serccn-aud negative dppara-
"a. than 10 aticnp; 20 draw the coior.ncs on set
q screens as the irish expert has done. H. how
ever IL proper machine dividing engine. Tor IN
stancc-bc employed. or II a printing press De- io""d
/ efncacious this serious difficulty might BE- over
come II would then De practicable for some en-
t.rpris.ns Manufacturer of Photographic apparatus
10 nut on the market sore ms OF the proper char
acter and thus enable all amateurs ID make thcir
own color photographs. For lantern-SieS cspn-
cially this wo i'd be a great desidcfainm why
would It not be a simple matter TO make and sell
both 4 scr, en- for use in the camera and similarly
lined covers for slides? special platehoiIer
would be necessary. 10 De sure bur that could
easily be provided LINT there a great opening in
this direction for somebody
SOFT CAPS oN CONICAL PEoJEcTILES.
HOW THEY iHcREAsE THE PENETRATING
POWER oF LARGE SHOT
,tnouyh much ingenuity has been expended IN
the Invention Of processes FOR hardening conc"l
solid shot used with modern ordnance. the IDEA OF
uniting cap 81 softer steel over the pom mas late
ly been tried both In Russia ana the United states
vl;h surprising results. England vas the hrst 10
make these experiments apparently p"l WITHOUT
meeting with cn encouraging desre" OF success
The notion was originally suggested 10y discovery
that II a thin sheal 81 soft wrough-iron Dc I"''
over a yiccl-faccd armorplate the latter inileh 10
hreak up a chilled steel prolcctile which woui'
| otherwise 40 to pieces upon hitting H. IN h'tu"
service OF COURSE the enemy could not be expected
/ ,o 1i,,hle own hrmOi In this manner iiut IT