Popular Science Monthly 



835 



cranks his machine the film is fed through 

 in a series of rapid jerks, the shutter action 

 being almost continuous. Sixteen pictures 

 are made on each foot of film. 



The cameraman, having completed his 

 work, the film is delivered to the developing 

 department. Gen- 

 erally a small piece 

 is clipped and de- 

 veloped to deter- 

 mine light and ex- 

 posure conditions 

 so that the entire 

 film may be treated 

 accordingly and 

 not spoiled. 



The developing 

 is done in large 

 tanks. The film 

 is wrapped around 

 large light frames 

 for convenience. 

 Thus mounted it 

 is easily dipped 

 into the bath, and 

 examined without 



Cementing together the 

 make a picture of the 



the direct contact of fingers. When the 

 negative has been developed it is placed 

 in the fixing bath. After that it is thor- 

 oughly washed in clean water. The de- 

 veloping and fixing are generally done in 

 two-hundred-foot lengths. It is difficult to 

 handle any greater length. 



Large drums made of light metal and 

 wood are used for drying the film. These 

 drums revolve slowly, thus throwing off 

 water adhering to the back of the film and 

 exposing the emulsion side to a constant 

 current of hot air. The drying room must 



be clean; for even the smallest particle 

 of dust on the film will be magnified many 

 times when the picture is screened. For 

 this reason many special devices ha^•e been 

 installed in modern dr\ing rooms to keep 

 them absolutely free from dust 

 and dirt. 



In printing the 

 positive from the 

 negative the ser- 

 vices of real ex- 

 perts are required; 

 uneven work will 

 produce a bad 

 "flicker" on the 

 screen. Printing 

 has been so highly 

 developed that the 

 old annexing 

 "flicker" has al- 

 most disappeared. 

 As in making or- 

 dinar}^ pictures the 

 emulsion side of 

 the negative is 

 brought into con- 

 tact with the positive film and is exposed 

 to the light. Artificial light is used because 

 it is more easily controlled than sunlight. 

 The printing machines used work on the 

 same principle as the motion picture 

 camera with the exception that they "take" 

 tAvo rolls of film, both the positive and 

 the negative. In developing the positive 



200-foot lengths of fihn to 

 standard 1000-foot length 



Photographing the titles and subtitles on films from 

 block-letter signs, with a regiilar motion-picture camera 



Printing the positive from the negative. 

 The printing is d<»ie by artificial light 



