CH. Ill] MAGIC LANTERN WITH SMALL CURRENTS 81 



FIG. 42. THE SMALL ARC LAMP OF THE SPENCER LENS Co. 



With this small arc lamp the two carbons may be moved separately or 

 together, as the carbon movement is like that of the larger lamps, i. e., one shaft 

 within the other, and the corresponding milled heads are placed close together, 

 so that either can be turned separately or both together. 



It is arranged for giving parallel or converging light. When used with the 

 magic lantern the special condenser and its tube are removed (fig. 47). 



automatic lamp are so adjusted, or may be so adjusted if desired, 

 that they will work with currents ranging from 5 to 25 amperes 



(fig. 41-44)- 



The small lamps (from their size, called "Liliput or baby" arc 

 lamps) are largely used for darkground illumination and ultra- 

 microscopy and for drawing. For these purposes they have a tube 

 attached with a condensing lens (fig. 41). For use with the magic 

 lantern the tube and condensing lens are removed (fig. i). 



