LIGHTNING. 29 



Q. Why is ELECTRICITY excited by FRICTION ? 



A. Electricity, like heat, exists in ail 

 matter ; but is often in a latent state : 

 friction disturbs it, and brings it into 

 active operation, (see p. 31.) 



Q. Why is a TREE sometimes SCORCHED by 

 lightning, as if it had been set on fire? 



A. Lightning scorches it by its own 

 positive heat, just the same as fire would. 



Q. Why is the BARK of a TREE often ripped 

 quite off by a flash of lightning ? 



A. As the lightning runs down the 

 tree, it develops the latent heat so 

 rapidly, that it carries the bark of the tree 

 along with it, while it seeks to escape. 



Q. Why are BOUGHS of TREES broken off by 

 lightning ? 



A. The mechanical force of lightning 

 is very great ; and when the flash strikes 

 a tree, it will often break off the boughs 

 by the force with which it strikes against it. 



Q. Why is an electric shock felt MOST at the 

 ELBOW JOINT? 



A. Because the path of the fluid is 

 obstructed by the joint : and the shock 

 felt at the elbow is caused by the fluid 

 leaping from one bone to another. 



