48 



THE MICROSCOPE 



Incandes- 

 cent gas 

 launp. 



Incandes- 

 cent spirit 

 lamp. 



An incandescent gas mantle, either of the ordinary or inverted 

 type, makes a good light. Its only disadvantage is that it 



cannot be conveniently used 

 with its image exactly in focus, 

 because the fine mesh of the 

 mantle does not then give a 

 continuous surface. This light 

 is sufficiently powerful for high- 

 power dark- ground illumination 

 if dark colour screens are not 

 used. 



For those who have not gas 

 or electric light, but who require 

 a more powerful light than a 

 paraffin lamp, an extremely use- 

 ful lamp, which is quite simple 

 to use and gives excellent re- 

 sults, consists of an incandescent 

 mantle heated by a methylated 

 spirit flame. The reservoir 

 having been filled with spirit^ 

 the method of lighting the lamp 

 is as follows. The cap of the 

 reservoir must be screwed off, and the bellows attached by screwing 

 in the nipple at the end of the tube. The bellows must be 



j^ 



Fig. 41.— No. 3337. 



Fig. 42.— No. 3338. 



squeezed till the burner is hot. The U-shaped metal piece 

 covered with asbestos should now be soaked in spirit and placed 



