Proceedings of the Farmers' Club. 327 



ask why these complicated and expensive forms have been adopted, we 

 shall be told that it is for the purpose of obtaining the greatest amount 

 of surface with the least amount of metal, and this is done because 

 electricity always resides on the surface. Those who reason in this 

 way, however, prove clearly that they have never studied the subject, 

 else they would be aware of the fact that, while static electricity at 

 rest always disposes itself on the surface of bodies charged with it, 

 electricity in motion pervades the entire substance of the bar through 

 which it passes, and consequently the power of such a bar to convey 

 electricity is measured by the quantity of metal that it contains, and 

 not by the extent of surface that it presents. Pouillet showed this in 

 a very clear and decisive manner. He measured the conducting 

 power of a fine wire of cylindrical form (the form that presents the 

 least possible surface in proportion to its cubic contents), and then, 

 having flattened and annealed it, he tested it again. Its surface was 

 enormously increased, but its power to conduct electricity was lessened 

 rather than otherwise ; this diminution being probably due to the 

 fact that the wire was increased in length, and, consequently, its cross- 

 section was somewhat diminished. 



We come now to consider the best method of attaching the rod to 

 the building. It is a very prevalent opinion that lightning-rods should 

 be carefully insulated from the buildings to which they are attached, 

 and hence most rods are made to pass through glass tubes or insula- 

 tors, the avowed object being to prevent the electricity from passing 

 into the building. The extreme worthlessness of any such arrange- 

 ments ought to be obvious to any person that ever observed a flash of 

 lightning, and the positively dangerous character of the insulators 

 will be apparent to every one that carefully studies the principles 

 which govern conduction and induction. That a flash of lightning 

 which will pass through a hundred feet of air should be unable to 

 pass from the lightning-rod' to any other object, merely because an 

 inch or two of glass is in the way, is a proposition too absurd to find 

 favor with any sensible man. In the first place, then, lightning-rods 

 should be connected with all large masses of metal which may exist 

 in or upon the house, such as metallic or tin gutters or pipes, iron 

 railings, etc. In the second place, the rod should be attached to the 

 house in the neatest and least obtrusive method possible. If the rod 

 be flat, it may be pierced with small holes and tacked directly to the 

 building ; but a better way, both for round, square and flat rods, is to 

 employ properly shaped staples of stout wire. These staples may be 

 driven into the studding of wooden houses. or into the joints of brick 



