172 Management of Light in Illumination. 



of a piece of wood, of about one inch in thickness. As 

 brackets are usually constructed in that manner, there 

 will be nothing uncouth in that form. 



What appears to be the foot of the basket is a portion 

 of a hoop of tin, painted and gilded like the flambeau, 

 which is attached to the opening of the basket below, 

 where it embraces the circular reservoir. This serves 

 for fixing the basket in its place, and also a handle for 

 removing it when the lamp is trimmed or lighted. 



The basket serves for hiding the burner and its glass 

 chimney, and for dispersing and softening the vivid 

 light of the flame. For those purposes an ornamented 

 balloon may be used instead of the basket, if that form 

 should be preferred; but, in all cases where balloons 

 are used, care must be taken that they be sufficiently 

 large, otherwise their surfaces will be too intensely 

 luminous not to injure the eyes. 



Globes of ground glass have been in use for some 

 time in France, and elsewhere, no doubt, for masking 

 the flame of Argand's lamp ; but their light has been 

 found to be too powerful to be agreeable. This is not 

 owing to any particular quality in ground glass which 

 renders its light dazzling and fatiguing to the eyes, but 

 it is merely owing to the too great intensity of the light 

 at the surface of the visible object, which is owing to 

 the smallness of that surface or to the smallness of the 

 balloon. 



As the surfaces of globes are as the squares of their 

 diameters, the surface of a globe of eight inches in 

 diameter is to that of a globe of four inches in diame- 

 ter as 64 to 16, or as four to one. 



Hence we see that the intensity of the light at the 

 surface of a globular screen of ground glass of four 



