VENTILATION OF DARK-ROOM. 



1 4' J 



Fig. I35.--- 



in use much of the time, some 

 Tlie writer accomplishes this 

 by an electric fan placed in the 

 mouth of an air-shaft which 

 extends from the ceiling to 6 or 

 8 feet above the roof These 

 shafts are c}'lindrical, i foot in 

 diameter, made of heavy sheet- 

 iron and surmounted by a broad, 

 mushroom - shaped cap. The 

 interior is painted a dead black, 

 and as an additional precaution 

 against the entrance of light it 

 carries a sleeve of tlie form 

 .shown in fig. 131. This effectu- 

 ally cuts out light. The air is 

 pumped out so rapidly by a de- 

 vice of this sort that not the 

 least inconvenience is experi- 

 enced in working all day in a 

 very small room. 



If only one or two persons 



The very convenient heavy camera 

 shown in fig. 124 ma)- also be used 

 for natural-size work, arranged as 

 shown in fig. 129. In tliis connection 

 the Starrett cross-level shown in fig. 

 130 will be found ver}' convenient 

 for leveling the back of the camera. 



Very excellent cameras are made 

 by the Centur}' Camera Company. 

 Their Long-focus Centur}- Grand 

 leaves little to be desired in the wa}' 

 of a convenient, perfect-working in- 

 strument. 



The dark-room for development is 

 an important subject. The cliamber 

 must be light-tight. At the .same 

 time it ought to be roomy and well 

 ventilated. If the room is small and 

 means of removing the foul air becomes imperative. 



Fig. 136.1 



*FiG. 135. — Diagram of sniall dark-room shown in iiy. 134. Standing in the middle, a man can 

 touch the walls in either direction. In the ceiling is a foot-wide pipe extending 6 feet beyond the 

 roof and capped with a broad mnshroom top. In the lower end of this pipe is an electric fan, 

 which pumps foul air out of the room. Light is prevented from entering by partial cross-septa 

 projecting from opposite sides of the air-shaft, and also by blacking its inner surface. 



■fFiG. 136. — Wall case for preserving from dust and scratches the enameled iron plates used for 

 squeegeeing silver prints. 



