Peculiarities of JHsrharges 323 



passage of the electric charge than others, and 

 when a considerable resistance is offered, heat 

 is produced in appreciable amounts at the 

 places at which the resistance is met. The 

 application of this principle will be seen when 

 the effects of real lightning are considered. 



In Figs. 131, 132, and 133 are shown light- 

 ning flashes taken by Mr. W. N. Jennings.* 



Fig. 131. Horizontal discharge of lightning. 



These flashes are so soon over that without 

 the aid of the sensitive photographic plate it 

 w^ould be impossible to study them. It will 

 be noticed that the path of the charge is not 

 straight, but quite irregular ; this path Ijeing 

 that in which there is the least resistance to 

 the passage of the electricity. One strange 

 phenomenon which is ])rought out clearly in the 

 pictures is that the dischai'ge very frequently 



*These three pictiires are drawn, by permission, from photographic illus- 

 trations by Mr. Jennings in Journal of the Franlilin Institute, vol. I'Sd (1892). 



