APPARATUS 



19 



thirteen compartments, each having a lens of the same 

 construction, and the same focal length; these are 

 arranged to correspond with the compartments in the 

 electro-exposors. 



One of the lenses is provided with a focusing 

 screen, and with it the other twelve lenses are 

 adjusted to a proper focus without removing the plate 

 holder behind them from its position in the camera. 



The plate holder is constructed to hold three dry 

 plates, each three inches by twelve inches; the front is 

 divided into twelve compartments, each three inches 

 square. 





Fig. 5. 



Light is excluded from the front by a roller blind, 

 strengthened by thin narrow slats of hard wood; the 

 blind works in grooves, is drawn over a concealed 

 roller, and covers the back of the holder when the 

 plates are being exposed. 



Figure 6 is a rear and side view of the circuit 

 maker, conventionally called the exposing motor. 



The motive power is an adjustable weight attached 

 to a cord which is wound around a drum. Twenty- 

 four binding posts are attached to the table at 



