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Three-colour Photography. 19 
collodion films consecutively printed in correct register on top of 
one another with the accomplishment of the same object, and 
the results of his labours in this direction are likely to constitute 
one of the most interesting displays at the forthcoming Paris 
Exhibition. 
There yet remains to be mentioned the very ingenious 
adaptation of the three-colour system invented by Prof. Joly, of 
Dublin. In accordance with his system the three primary 
colours are all included in alternating microscopically minute 
parallel lines ruled upon a single original or taking screen, and 
in the reverse or complementary order on a corresponding or 
viewing screen, which has to be bound up in perfect register 
with each resulting positive. 
The impression to the eye of these Joly pictures, with their 
serried lines, while very pleasing, is highly suggestive of a piece 
of tapestry work, and when greatly enlarged upon the lantern 
screen the objects delineated present the aspect of being viewed 
through a wire cage, or thin closely approximate park railings. 
This aggressive prominence of the ruled colour lines is un- 
doubtedly a fatal obstacle to the utilisation of the Joly process 
for the colour registration of subjects requiring scientifically 
accurate reproduction of their minuter details. 
Neither of the several systems hitherto enumerated fulfilling 
the requirements of the easy practical application and scientific 
accuracy that is in demand, I will now pass on to the introduc- 
tion and illustration of that modification of the three-colour 
process which, so far as my personal experiments and experience 
is concerned, appears to me to hold out the most encouraging 
future prospects. In common with the original Ives transparency 
system, the construction of the final positives has much in 
common with the ordinary carbon process, but with modifi- 
cations that have been specially devised by Mr. E. Sanger 
Shepherd, a former collaborator with Mr. Ives. The essential 
details of Mr. Shepherd’s process are described in a paper on 
*Three-colour Lantern Slides,’’ communicated by him to the 
meeting of the Royal Photographic Society, held on Nov. 28th, 
1899, and are published at some length in the ‘ British Journal 
of Photography’ of Dec. 1st of the same year. The practical 
application of this Sanger Shepherd lantern slide process has 
been so far assured that all the materials and instructions for 
its employment are now obtainable through the ordinary com- 
mercial channels, so that anyone possessed of a camera and 
ordinary manipulative skill can compose his own natural colour 
pictures. 
Before proceeding to submit to you some few results of my 
own experiments with this process, I may briefly explain that 
the negatives from which the slides have been produced were all 
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