Management of Light in Illumination. 113 



with one single luminous body (in order to avoid the 

 bad effects of cross-lights), it was necessary to con- 

 struct illuminators of different sizes and also of differ- 

 ent forms. 



There are three varieties of them in use which have 

 all been found to answer very well the different pur- 

 poses for which they were particularly designed. 



1. The Balloon Illuminator, which is a luminous 

 globe of 1 8, 20, or 22 inches in diameter, suspended 

 from the ceiling at the height of 7 or 8 feet, designed 

 for lighting saloons, drawing-rooms, ball-rooms, etc. 



2. The Dining-Room Illuminator, which serves like- 

 wise for lighting a billiard-room in great perfection. 

 This is likewise suspended from the ceiling; but its 

 screen, instead of being globular, is in the form of a 

 dome, with a hoop about four or five inches in width 

 suspended from the bottom of it. 



3. The Table Illuminator, which is covered by a 

 hemispherical screen or dome, is placed on a stand or 

 foot about twenty inches high, and is used for lighting 

 a dining-table or reading or working table ; and it 

 lights the room at the same time quite sufficiently, if 

 the room be not large. 



All these illuminators have circular horizontal reser- 

 voirs for the oil, which have all the same depth, 

 viz., one eighth of an inch, but which are of different 

 widths and diameters, according to the number of 

 burners which they are destined to supply. 



These burners, whatever may be their number, are 

 all placed close together, in a cluster, in the centre of 

 the reservoir, and so near as to touch each other. 

 They have hitherto been constructed on Argand's 

 principles, and each of them is furnished with its sepa- 



VOL. IV. 8 



