252 LIGHTNING-RODS. 



pieces are brought in contact at the outer edge, so as to 

 form a united surface. If a square rod is used, notch the 

 corners with a single downward stroke of a cold chisel, at in- 

 tervals of two or three inches. No part of the rod should 

 be painted, as its efficiency would be greatly impaired. Let 

 the upper extremity consist of one iinely drawn point of 

 copper or silver, or well gilded iron, to prevent rusting. 

 Let the lower part of the rod, at the surface of the ground, 

 terminate in two or three flattened divergent branches, lead- 

 ing several feet outwardly from the building, and buried at 

 a depth which reaches perpetual moisture, in a bed of char- 

 coal. Attach the rod to the building by clasps protruding 

 three or four inches and containing glass rings or funnels 

 for the rod to pass through. The rod must not touch the 

 building nor the iron clasps, but only the glass ; because, the 

 latter being a non-conductor of electricity, in the event of 

 the rods being struck by lightning, the charge is conducted 

 harmlessly to the ground, having no point of contact with a 

 conductor by which it might be led into the building. Upon 

 reaching the top of the building the rod should be conducted 

 to the centre of the ridge, and the end should then be raised 

 to a height equal to one-half of the distance to the end of 

 the ridge. If the roof is irregular in height, of course judg- 

 ment must be used in fixing the point where the end of the 

 rod rises above the roof, bearing in mind this important 

 consideration that the rod protects objects at twice the 

 distance of its height above any point in a line perpendicu- 

 lar to its upper termination. 



