392 MOVING PICTURES [Cn. XI 



as red and greenish blue, yellow and indigo blue, etc., give the 

 appearance of white. With this information it became possible 

 to add to the photographic black and white moving pictures, the 

 element of color. This was accomplished by using isochromatic or 

 panchromatic film, and taking the pictures through colored screens, 

 the first picture through a red, the second through a green, the 

 third through a violet screen and this constantly repeated through- 

 out the whole scene. In exhibiting the picture there is a three- 

 color screen used so that the picture exposed through the red screen 

 is projected through a red screen, giving a red image, and the other 

 colors in like manner. If the film is run through the machine three 

 times as fast as the black and white film, then the brain mixes the 

 colors of the successive pictures giving fairly true color values and 

 black and white. Where only two screens are used red and green 

 the process is the same, but the film has to be run through the 

 machine only twice as fast as the black and white film as there are 

 but two colors for the brain to combine. Naturally the combina- 

 tion of two colors gives a lower range of possibilities than the mix- 

 ture of three colors, but even this is wonderful, as all will agree who 

 have seen the colored moving pictures reproducing the gorgeous 

 scenes of nature or the pageants of human splendor in all their 

 form and movement and also with a fair approximation to the color 

 effects. 



So perfect have become the materials and processes used in 

 photography, and the accessory mechanical appliances, and the 

 artificial lights available, that now the scientist can register 

 accurately the almost instantaneous movements of an insect's wing, 

 the flight of a cannon ball, and the numberless actions everywhere 

 in nature which are so rapid that the unaided eye cannot analyze 

 them. On the other hand, the movements in the processes of 

 nature which are so slow that one can only see what has been 

 accomplished in an hour, a day or a year, can be hastened by the 

 moving picture machine so that the actual changes can be made to 

 appear as if they occurred in a brief time, and the actual move- 

 ments which were too slow for the eye to recognize, are made to 

 appear rapidly enough for the eye to follow them. In this way the 



