atmospbertc Electricity 81 



metal roof they should be connected with it. 

 Then connect the roof with rods from several 

 points with the ground. Here is where most 

 rods fail. The ground connection is not 

 sufficient. The earth is a poor conductor, and 

 we have to make up by having a large metal 

 surface in contact with it. It is best to have 

 the rod connected with the water pipe, if there 

 is one, and have it connected with metal run- 

 ning all around the house as low down as the 

 bottom of the cellar, for sometimes there is an 

 upward stroke, and you never can tell where it 

 is coming up. If you have a heating system 

 it should be thoroughly grounded and the top 

 pipe connected with the rods at the chimneys. 

 These rods need not be insulated as is the 

 usual practice. 



If you are outdoors during a thunder-storm 

 never get under a tree, but if you are twenty 

 or thirty feet away it may save your life, be- 

 cause, if it comes near enough to strike you, 

 it will probably take the tree in preference. 

 It seeks the earth by the easiest passage. An 

 oil-tank and a barn are dangerous places, if 

 the one has oil in it and the other is filled with 

 hay and grain. A column of gas is rising that 

 acts as a conductor for lightning. Of course 

 if the barn is properly protected with rods it 

 will be safe. Sometimes a cloud is so heavily 

 ehanr <] that the lightning comes down like an 

 avalanche, and in such a case the rods must 



