CHEONOPHOTOGRAPHY ON MOVING PLATES 117 



passes through this aperture, and forms an image on 

 the moving film, which has previously been brought 

 into focus. 



The film unrolls itself bv a series of intermittent 



Frc 81.— Admission shutter which is substituted for the dark slide when working 

 with a roll of film. The size of the aperture can be regulated by the side scieens 

 R K, according to the dimensions of the intended image. 



movements, by means of a special mechanical arrange- 

 ment, which enables it to pass from one bobbin to 

 another. The arrangement of these bobbins must 

 first occupy our attention, for the possibility of loading 



H 



Ftg. 82.— Two metal bobbins for carrying the sensitized film. The two bobbins are 

 placed in different positions : the letters H and B indicate respectively the upper 

 and lower parts. 



or unloading in the light is dependent on their 

 construction. 



The bobbins are made of metal, and two projecting 

 plates are fixed to the two ends of a light cylinder. 

 The upper of these plates is thin and the lower one 



