DISRUPTION OF ROCK BY LIGHTNING 571 



not always accompanied by high temperatures, it does not follow that 

 this phenomenon may not have been caused by lightning. 



The most evident effect of lightning is of the disruptive type 

 observed almost every day in the form of splintered telegraph poles 

 and shattered trees and buildings. Lightning, producing this class 

 of results, does not seem always to be accompanied by high tempera- 

 tures. The writer has observed one instance at least in which a per- 

 fectly dry wooden building was shattered without a tendency to firing it. 



