ELECTRIC LIGHTS. 



161 



ing through the front hole as through a window. The 

 lime soon gets white hot, and adds its luminosity to 

 that of the carbons. If there be a degree of 'un- 

 steadiness in the arc itself the lime does not so quickly 



ELECTRIC LAMP IN LANTERN. 



cool, and the field is kept bright until the current is 

 fully established again. 



TO PROJECT THE ARC LIGHT. 



It is only necessary to place an ordinary lens three 

 or four inches in diameter and a foot focus that 

 is, the ordinary projecting lens described on page 25 



