Systems of Bodding 327 



generated, and tlnis prevent its accumulation to 

 a dangerous extent. Very high towers, such as 

 steel windmills, high trees, and steeples do the 

 community a good service in this respect. But 

 sometimes the discharges cannot be dissipated 

 through the brush form, but reach a high pres- 

 sure, and exhibit themselves with great violence, 

 producing the booming and crackling noise of 

 thunder. This is the second form; and although 

 the points may be useful in this case too, yet if 

 they are too far apart the discharge may not 

 seek them, but may take a shorter path through 

 the moist hay from which the hot, damp air is 

 rising to the roof and forming another lightning 

 conductor. Protection from this can be partly 

 provided by the use of several points, not over 

 forty feet apart; but in cases in which lightning 

 is very violent and frequent, the conductor 

 should be run all around the edges of the roof, 

 and in several places to the ground. 



An experiment made by a noted electrician 

 some years ago will illustrate this point: A 

 frame was made of iron wire in the shape of a 

 barn, the wire representing the edges of the 

 walls and roof. The frame was connected to 

 the ground, or "grounded," as the electricians say, 

 and then artificial lightning was allowed to play 

 upon it from a distance of a foot or more above. 

 This gave a model about in proportion to the 



