ILLUMINATION. 



39 



Fig. 19 shows a simplified form of that used by 

 Dr. Dallinger and described in the Journal of the 

 Microscopical Society. 



To the back of an ordinary tin paraffin lamp A, a 

 board is attached to give rigidity; this board 

 is fastened by screws to a block which can be 

 raised or lowered on the pillar D by a rack and 

 pinion movement. A lateral motion is communi- 

 cated to the pillar D by means of the screw F. 



Fig. 19. 







The lid of an oblong tin box about one inch wider 

 than the chimney of the lamp, has a hole cut in it 



