ILLUMINATION. 
77 
has had has not been very satisfactory. But improve¬ 
ments are constantly being made both in carbons and 
in utilisation of current, and a perfect electric lamp 
may yet be found. 
Fig. 24. 
We content ourselves by figuring (fig. 24) a lamp, 
the Davenport, which is simple, efficient under suitable 
conditions, and well known in the market. 
An incandescent electric lamp may also be used, as 
it is by Dr. Van Heurck, but here again, unless a 
paralleliser is introduced, we shall get an unsightly 
image of the filament under certain conditions. 
On the whole we may fall back upon two radiants, 
both of which are well known, an oil lamp and the lime¬ 
light. The lime-light is much more intense and actinic 
than the oil lamp, and shortness of necessary exposure 
