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BELL SYSTEM TECHNICAL JOURNAL 



being determined by means of a slow acting relay or by a sequence 

 switch. It is desirable to stop the film from rotating before photo- 

 graphing the clock which may be done by means of the same relay 

 that turns off the lamp, or by means of a sequence switch. 



Main Features of Continuous-Film Oscillograph 



A picture of the continuous-film oscillograph is shown in Fig. 10. 

 It differs from the polar oscillograph mainly in the form in which 

 records are obtained. As previously stated, records are made in 



Fig. 10 — Continuous-film oscillograph with covers removed. 



rectangular coordinates on a strip of film and may, therefore, be of any 

 length depending only on the length of film available and on the size of 

 the storage magazines. The oscillograph shown makes records on 

 motion picture film or sensitized paper of the same width. The film is 



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Fig. 11 — Circuit for lighting lamp quickly. 



Stored in standard magazines for motion picture film holding up to 

 200 feet. It is advanced by means of a motion picture sprocket 

 driven through gears and a magnetic clutch from a variable speed 

 motor. The optical system is practically identical with that used on 

 the polar oscillograph. 



