72 



and the other by what is correctly described as Screen Plate 

 Photography. 



Mr. F. E. Ives, of Philadelphia, may be said to be the pioneer 

 in practical three colour work, and when his results were made 

 known in 1895, they created quite a sensation in the photographic 

 world. He produced most elaborate cameras for taking the 

 pictures, and equally elaborate instruments for viewing them. 

 His was the first practical colour photography, and it was based 

 upon selective absorption. 



The next successful attempt was the Sangar Shepherd Three 

 Colour Process. It was on the same lines as the Ives in its main 

 principle, but the three negatives were superimposed so as to form 

 one plate which could be thrown on the screen. 



Our last consideration is the Screen Plate Photography 

 previously referred to. In this the photographic basis is the 

 panchromatic plate in which there is no colour whatever, the 

 colour being provided by the use of a screen previously prepared 

 with coloured pigments, and brought into contact with the photo- 

 graphic plate for viewing purposes. The panchromatic plate has 

 been explained as giving the best rendering of colour values yet 

 attained. The screen may be made in many ways, though two 

 only are chiefly used. The one is by a mixture of fine coloured 

 particles dusted on to a plate; the plate is then varnished, thus 

 forming the screen ; it is then coated with panchromatic emulsion 

 on which the photo is taken. After development it is, of course, 

 a negative, but by a chemical process it is changed into a positive 

 and is then ready for use. This is the Lumiere process. The 

 other method is described as geometrical, the colours being put 

 on in lines forming tiny squares of red, green, and blue. In this 

 the panchromatic emulsion is put on a separate plate, and a 

 positive obtained in the usual way as in making an ordinary 

 lantern slide. These two plates are brought together and bound 

 up, ma'king the complete colour picture. This is the method 

 adopted by the Paget Co. These two plates, the Autochrome 

 and the Paget, practically hold the field to-day; they are fre- 

 quently shown together, and may be considered in a sense rivals. 

 That in all cases they give a true rendering of colours in nature 

 may be doubted. The density of the Autochrome renders a 

 specially strong light necessary, which is not the case with the 

 Paget. Greens seem to be better rendered in the Paget than in 

 the Autochrome, while yellows seem to be given better in the 

 latter than in the former. Autumn tints are particularly well 

 rendered in the Paget; there would, therefore, appear to be a 

 sphere of usefulness for both. . 



The space allowed for this paper is so limited that the subject 

 cannot be dealt with as fully as could be wished, it must, there- 

 fore, onlv be regarded as a broad outline of a particularly 



interesting subject. 



