New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1903-10-11

dark room, and light from suitabls source -
permitted 70 shine through them az the right
moment In front OF each negative 70 o Lens
that focuses that particular picture upon q fresh
sensitive plate. the two lenses being aimed In
such way that the images VII unite TO form
one. A novice might expect that the apparatus
would be adjusted so that the coincide1ce would
be fundamentally exact: but for reasons that
will presently appear Mr.. Ives keeps one picturs
Just hairs breadth COR less than a hairs
ol eadth) to thu right hand OF the other Final
~. before the light IA turned On ard ths work
OF exposure begins. one more agent Is intro
duced- In front OF this sensitive plate. and re-
moved from ii at a distance OF about one-thir-
tieth Of an fnch-34-1 900. TO be sxact-is piece
OF glass on which fine black lines. arranged YER
ticaIly. have previously been produced by photo
graphic means Such a plate IS known q
screen. and IN the present Instance the lines
run hundred to ths inch The intervening
clear spaces are the least BIT narrower than the
lines for reasons that need not here be dis
cussed. but have much importance IN optics
Hence the lines are each little more than a
two-hundredth OF an inch wide. and the inter-
walls between them little less
Two consequences result from this general ar
rangement- One Is that the picture now being
made Is broken up into perpendicular lines.
Only rays which pass through the clear spaces
IN the screen car. act upon the chemicals with
which the sensitive plate IL coated Those which
are obstruCted BY the lines OF the screen are in
effective. Owing TO the conveyance OF the paths
OF the two ina zes. both OF the latter strike the
screen ar an angle. one from the right and the
other from the LETT. and not squareIy. Light
rays from two separate sources meet and cross
at each OF the clear spaces in the screen and
having crossed. diverge again after going
though VALE the two original images ars
made to co.nCf1s with the utmost precision, On
the screen therefore. separation Is Effected On
the sensitive rlate behind Thus on the positive
each huIdreEth Of an inch OF sc1ce IS divided
into four psrts-tTO vertical slices % photo
graph. each alternating with a blank.
The plata. when cleared and fixed with no
proper sOlfltiOns must be subjected 70 one more
treatment before 4 "a finished II one examines
II in its present condition. he has the sensa-
ton OF seeing double. To produce the desired
the positive e cover glass. on which are lines
exactly Ike those OF the screen The ADJUST
meur m1sst be made with great precision or the
thing vii be spoiled further precaution TO
just the right distance. By interpOsinS card
board Of the right thickness az al four edges
Though = Is probable that a heightened per-
spectfve could be obtained IN archltectUral SUD
tects By the method here described. the latter
Is IYkslv 20 be applied first 70 portrait work Mr..
Ives say-s that bv modification OF the system
which nv photographer would think Of. num-
b,r % .cpses can be made instead or only ora-
'rta ARTIST would need only 70 get Two old fash
toned positfves on glass rom rs Original mega
49,, Af,er that proceeding duplication would
Re n s{-rpIe matter. Moreover. II the necessary
-s.o,.chsng were done the first negativeS
me would be trouble on that score