128 LIGHTNING CONDUCTORS. 



and discharges steadily on to the earth beneath, occasional flashes between cloud and earth may pass ; 

 but these can be readily dealt with by an efficient system of lightning conductors. In any case, the points 

 of the conductors are a means of silently discharging that part of the cloud which lies immediately above 

 them, so that the stroke is less likely to take place in their immediate vicinity, A stroke of the B class 

 is much more complicated, and occurs when a flash passes between cloud and cloud, leaving an unbalanced 

 charge of electricity on the lower side of the lower cloud, which immediately flashes to earth with terrible 

 violence and travels in a most erratic path; Cases have been known where the flash has travelled 

 halfway down an isolated lightning conductor and then left it, piercing brick walls and running to earth 

 through gas pipes, water pipes and even bell wires. 



The only way to protect a building absolutely from such flashes would be to build a gigantic wire 

 cage over it ; and as this is impracticable, the next bast arrangement is to fix lightning conductors in 

 a manner representing the Iramework of such a cage. This can be done by erecting a number of small 

 rods on the various prominent features of the building (one is wholly insufficient, save in very exceptional 

 cases) and connecting them all together by. means of conductors running along the roof ridges and 

 supported a few inches above them. Horizontal conductors should also be run to the rain-water pipes, 

 iron finials, etc. ; in short, to all the external metal-work on the building. The vertical conductors 

 which join the rods to earth should run straight down the side of the biiildiiur, and to enable this to be done 

 easily they should be held a few inches away from the wall by special bolts so that they will clear any 

 projecting masonry without leaving the direct line. The bottom end of the conductor should be connected 

 to a metallic plate surrounded by a quantity of broken coke and buried in permanently damp ground. 

 If this last condition cannot be fulfilled without excavating to a great depth, a &quot; tubular earth &quot; can be 

 used ; in this case the conductor is led into a pointed irot tube which is driven well into the ground and 

 filled with broken carbon, a little water from the nearest rain-water pipe is diverted into this tube, and 

 leaks through the bottom of it, keeping the ground moist all round. 



The manufacturers of lightning conductors still make them, for the most part, of copper, though the 

 best scientific authorities have declared iron to be quite as good from an electrical point of view, the 

 disadvantage being that it corrodes more easily. In the case of a country house well away from the smoky 

 atmosphere of towns, galvanised iron conductors ought to be quite satisfactory, and, of course, very much 

 cheaper. The very fact that they are more liable to corrosion than copper is an additional element of safety, 

 because it makes a periodical inspection necessary. It is most unwise to assume that lightning conductors in 

 copper or any other material, having once been erected, require no further supervision. In the course 

 of time many things may happen to them at the hands of workmen engaged in repairs to the building, 

 and a thorough inspection by a qualified person, say, once in three years, would appear to be a very 

 necessary precaution. 



There is no reason why a system of lightning conductors should be at all unsightly; but British 

 manufacturers do not seem to have grasped the fact that the terminal of a lightning rod is necessarily 

 part of the decorative scheme of the building, and one sometimes sees some grotesque examples of 

 scientific Philistinism which architects and electricians on the Continent would have avoided. A finial 

 containing numerous small points is better electrically than one containing few large ones, and can in 

 most cases be adapted more easily to the architectural scheme. It is sometimes asked, &quot;Which is the 

 safest place during a storm ? &quot; A banker s steel strong-room would protect anyone inside it absolutely, 

 but few would allow their fear of lightning to carry them so far as to make use of that. The next safest 

 place is a house with an efficient system of lightning conductors. It is perhaps needless to say that 

 lightning conductors should not be handled or even approached too nearly during a storm, and the same 

 caution applies to any metal-work connected to them. For the same reason it is inadvisable to walk in 

 close proximity to a long stretch of iron railing when caught out in a storm, and the old caution against 

 sheltering under a tree holds as good to-day as ever. The danger here is twofold, for if the tree is struck 

 by a powerful flash it may burst into hundreds of pieces, which will be projected outwards over a large 

 area, killing or maiming anyone in their path, or if the flash is not powerful enough to burst the tree, it 

 still may find a passage to earth for part of its charge through a human body standing near. 



MAURICE HIKD. 



