THE ORCHID REVIEW. 



NOVEMBER, 1902. 



COLOUR PHOTOGRAPHY. 



At the Royal Horticultural Society's meeting held at the Drill Hall, 

 Westminster, on Oct. 21st, there was a very interesting exhibition of 

 photography in natural colours, by Mr. T. Knight Barnard, of The Grove, 

 Hammersmith, including Orchids, vases of flowers, landscapes, &c, in 

 which the shapes and natural colours of the objects were reproduced with 

 remarkable fidelty. The objects shown were not coloured photographs 

 in the ordinary sense, but what may be termed photographic colour records, 

 which are placed in a special viewing instrument, comparable to the 

 stereoscope, to produce the effect mentioned. The colour records can be 

 multiplied indefinitely, and we believe that Mr. Barnard intends to place 

 them, together with the viewing instrument, upon the market, so that 

 anyone possessing them can at a few moments' notice produce the pictures 

 for the delectation of his friends. And with the special camera necessary 

 one could secure permanent records of his favourite Cattleya, or his 

 choicest variety of Odontoglossum crispum for future use. One can fancy 

 the utility of such a set of records at the Sale Rooms, when some special 

 variety was to be disposed of. Indeed the possibilities of the system seem 

 endless, if the cost is not prohibitive. 



The principle is based upon what is known as the Young- 

 Helmholtz theory of colour vision, which assumes that there are three 

 fundamental colour sensations, a red, a green, and a violet, and that 

 all other colours are compound sensations, or combinations of the 

 same. The application of the principle is as follows :— Three negatives of 

 any object are taken with screens of the three colours mentioned above, 

 which allow their own kind of colour rays to pass, while cutting off 

 those of the other two kinds. From the three resulting negatives three 

 ordinary positives are now made, and these are viewed through three 

 suitably coloured glasses, and afterwards combined to give the desired 

 picture. We are unacquainted with the details, but a further extension 

 of the process, in which the three positives are combined to form 

 pictures in natural colours, by what is termed photographic three-colour 

 printing, is one in which many of our readers are interested, and 



