346 THE FARMEPwT. [Chap. III. 



fully provided with lightning-rods. This may be owing to bad constniction 

 of tho rods. In the case of a groat explosion, like the one in Xew ITainp- 

 sliirc, it is not likely that a single rod eoukl convey all the charge to the 

 ground. If a rod was full of points along its length, it would serve to dissi- 

 pate tlie charge, and a square rod is better than a round one. 



Wni. S. Carpenter, of the eastern part of "Westchester County, IS". Y., says : 



"The farmers iu my section have no faith in lightning-rods, because the 

 proportion of barns that have been stnick with rods upon them is greater 

 than those without conductors. A scientific work states that a copper rod 

 one inch in diameter is better than an iron rod four inches in diameter, and 

 nothing less than that seems to be sufficient. This rod, too, must be contin- 

 uous, and well connected at the bottom with damp earth." 



Cases have occurred where a tin roof appeared to act as a great absorbent 

 of the electricity, which it conducted down the tin water-spouts, and in one 

 case into a water-cask, which it burst, a'nd passed on into the wet cartii. 



Single rods are apparently not always reliable. It is not doubted that an 

 extensive spread of metal difluses lightning. Then, are buildings safe with 

 metal roofs ? Flagstaffs have been torn to pieces on their tojis, and no mark 

 of injury left about the dwelling. Would it not answer the purpose and be 

 also economical to place a stout rod on the center of a wooden roof, and at- 

 tach to the bottom, where it touches the roof, a number of telegrapli wires, 

 carried in many directions to the ground ? Would the stroke on the center 

 rod be carried safely off by such radii ? If so, the plan is vastly cheaper 

 tlian an entire metal roof. Faraday experimented on iron cages suspended 

 in air — in one of them a man ; in another small cylindrical one, a mouse. 

 The cages poweifully charged with electricity, produced no effect on the 

 man or mouse. The plan of one central rod, with many wires covering the 

 building, may produce like results. 



It is worth a trial. It is also worthy of observation how many more barns 

 than houses are struck by lightning. A calculation of an average of seven 

 persons to a dwelling in the United States, basing the population at 

 30,000,000, would give 4,200,000 dwellings. And assuming that there are 

 5,000,000 of farmers, we may say there are 700,000 barns. Now, greatly 

 as the number of dwellings exceeds that of barns, our opinion is that there 

 are two barns to one dwelling destroyed by lightning. 



The impression is common, that barns when first filled with the harvest 

 are attractive of the fluid by the medium of the ascending gas of their con- 

 tents. This is probably true, and it is our opinion that a rod to serve as 

 a conductor, so as to be a sure protection, must reach higher than this col- 

 umn of vapor. Some barns need several rods ; others may need but one. 

 It depends upon the location very much, whether on a damp or dry soil, etc. 



Prof. Kenwick, of New York, says : 



"I doubt whether a barn was ever struck by lightning which was prop- 

 erly protected by a conductor." 



Ah ! but what is that proper protection ? That is what we would gladly 



