166 THE ELECTKIC LIGHT. 



light is essentially given by the carbons ; you 

 see that one is much more luminous than the 

 other, and that is the end which principally 

 forms the spark, the other does not shine so 

 much, and there is a space between the two 

 which, although not very luminous, is most 

 important to the production of the light. Dr. 

 Tyndall will help me in showing you that a 

 blast of wind will blow out that light ; the 

 electric light can in fact be blown out easier 

 than a candle. We have the power of getting 

 our light where we please ; if I cause the elec- 

 tricity to pass between carbon and mercury I 

 get a most intense and beautiful light, most of 

 it being given off from the portion of the mer- 

 cury between the liquid and the solid pole. I 

 can show you that the light is sometimes pro- 

 duced by the vapour between the two poles, 

 better if I take silver than when I use mercury. 

 Here is the carbon pole, there is the silver, and 

 there is the beautiful green light which conies 

 from the intervening portions. Now that light 

 is more easily blown out than the common 

 lamp, the slightest puff of wind being sufficient 

 to extinguish it, as you will see if Dr. Tyndall 

 breathes upon it. 



