126 Management of Light in Illumination. 



be not sufficient to allow the counterpoise to rise high 

 enough to permit this to be done, a light stand with 

 steps, such as are used in libraries, may be employed to 

 get up to a proper height to perform that operation, 

 without lowering the illuminator. When rooms are 

 so low as to render the use of steps necessary in this 

 operation, as there will be no longer any use for pul 

 leys, the illuminator may be suspended from the ceiling 

 by a simple cord, or by a thin rod of iron, having a 

 hook at each end of it. 



The first thing to be done in preparing to remove 

 the reservoir is to unhook the movable chain and lay 

 it aside ; the upper part of the balloon (the dome) is 

 then to be lifted up and taken away, care being taken 

 not to derange the chimneys of the burners ; the screw 

 belonging to the opening by which air is admitted into 

 the reservoir is next to be screwed down fast, and this 

 precaution must never be omitted. 



As soon as this is done, the reservoir may be lifted 

 up and taken away, as there will be no longer any dan- 

 ger of the oil being thrown out of it in carrying. 



If the illuminator be suspended by pulleys, a weight 

 must be at hand equal to the weight of the reservoir, 

 which must be hung to the brass hoop which supports 

 the reservoir. This is necessary, in order to prevent 

 the hoop from being suddenly drawn upwards by the 

 descent of the counterpoise on the removal of the 

 reservoir. 



A temporary stand, about 6 or 8 inches in height, 

 must be provided in the room where the illuminator is 

 cleaned and arranged, on which the reservoir can be 

 placed in a situation perfectly horizontal. In this situa- 

 tion it remains placed on a table, while its burners are 



