SCIENCE IN THE INDUSTRIAL WORLD 



single image taken and looked at through a tri-colored 

 film. 



With the three images or records made by three 

 exposures through colored screens, there are, again, 

 two ways of forming the picture. By means of a set 

 of three optical lanterns, each giving one of the required 

 colors, the image may be thrown, superposed, upon 

 a screen, the combination giving a colored represen- 

 tation of the photographed object ; or the three records 

 may be directly superposed. The latter is the basis of 

 three-color printing, as we have seen. 



The combining of three negatives by means of an 

 optical lantern thus obtaining views in natural colors 

 is an important branch of color photography, though 

 its practice is attended with considerable difficulty, 

 especially in the matter of matching the plates to secure 

 the right effect when combined. The whole process, 

 however, has recently been simplified to a considera- 

 ble extent by a French scientist, M. Andre* Cheron. 

 He has devised a three-lens camera which takes the 

 three views (one with each color screen) upon a single 

 plate and at one operation. But the ingenious thing 

 about M. Cheron's apparatus is that it serves as the 

 lantern as well. A lantern transparency is made from 

 the negatives and this is placed in the camera in the 

 portion occupied by the original photographic plate. A 

 lamp, Welsbach burner, or any good light serves to pro- 

 ject the three images, and these pass through a large 

 condensing lens placed in front of the camera lenses, 

 thereby superposing the images upon the screen. 



But all the while that the three-image process of 

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