No. 56.— 1905.] PHOTOGRAPHY OF COLOUR. 
THE PHOTOGRAPHY OF COLOUR AS APPLIED TO 
OBTAINING CORRECT COLOUR RECORDS OF 
NATURAL HISTORY SUBJECTS. 
By W. Saville-Kent, F.L.S., &c. 
The subject that I have the honour of bringing before 
you this evening is that of reproducing in connection with 
photographic processes the natural colours as well as the 
external form of the objects photographed, and this with 
reference more especially to their utility for obtaining 
correct colour records of Natural History subjects. 
Before proceeding to the exhibition of the examples 
I have at disposal for the illustration of this subject, it has 
occurred to me that a brief account might be acceptable of the 
sundry steps and methods that have been successively em- 
ployed in the development of colour photography to its 
present advanced state. 
Although it is only within recent years that anything 
approaching satisfactory results have been accomplished 
in this connection, it is an interesting fact that quite fifty 
years have elapsed since the possibilities of what is popu- 
larly known as colour photography were definitely demon- 
strated. At that relatively early date, however, no photo- 
graphic plates were manufactured that were sufficiently 
sensitiveto, or specially adapted for, the registration of those 
colour rays that enter essentially into the composition of 
the natural colour picture, and it is only by slow and 
tedious steps that all these difficulties have been finally 
overcome. 
At the present day there are, as a matter of fact, several 
more or less distinct processes by which photographic 
images of objects in their natural colours can be recorded. 
The majority of these processes are associated with what 
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