256 AMERICAN AGRICULTURE. 



chisel, at intervals of two or three inches. Each of these 

 will thus become a point td attract and conduct the electricity 

 to the earth. A bundle of wires, thick ribbons, or tubes of 

 metal, would be much better conductors than an equal quan- 

 tity of matter in the solid, round or square rods, as the con- 

 ducting power of bodies, is in the ratio of their surface. No 

 part of the rod should be painted, as its efficiency is thereby 

 greatly impaired. The upper extremity may consist of one, 

 two or more finely drawn points, which should be of copper, 

 silver or well gilded iron, to prevent rusting. The lower part 

 of the rod, at the surface of the ground, should terminate in 

 two or three flattened, divergent branches, leading several 

 feet outwardly from the building, and buried to the depth of 

 perpetual moisture in a bed of charcoal. Both the charcoal 

 and moisture are good conductors, and will ensure the passage 

 of the electricity into the ground, and away from the pre- 

 mises. The rod may be fastened to the building by glass or 

 well seasoned wood, boiled in linseed oil, then well baked and 

 covered with several coats of copal varnish. 



The conductors of electricity in the order of their conduct- 

 ing form, are copper, silver, gold, iron, tin, lead, zinc, platina, 

 charcoal, black lead (plumbago,) strong acids, soot and lamp- 

 black, metallic ores, metallic oxides, diluted acids, saline solu- 

 tions, animal fluids, sea water, fresh water, ice above 0, living 

 vegetables, living animals, flame, smoke, vapor and humid 

 gases, salts, raritied air, dry earth, and massive minerals. The 

 non-conductors in their order, are shellac, amber, resins, 

 sulpher, wax, asphaltum, glass, and all vitrified bodies includ- 

 ing crystallised, transparent minerals, raw silk, bleached silk, 

 dyed silk, wool, hair and feathers, dry gases, dry paper, parch- 

 ment and leather, baked wood and dried vegetables. 



