Construction, &c, of Lightning Conductors. 9 



Art. IV. — Suggestions for the Construction and Erection 

 of Lightning Conductors. 



By R L. J. Ellery, Esq. 



[Read 15th September, 1873.] 



A building constructed entirely of metal without joints, 

 except such as be metallically made, as by soldering, 

 brazing, &c, and being in full contact with the earth, would 

 be safe from the injurious effects of lightning. 



A building of brick, stone, wood, or other imperfectly 

 conducting material, will be well protected, if caged over by 

 a network or grating of metal wire or rod, all metallically 

 soldered into one continuous system, having projecting 

 above it at one or more places, metal rods forming part of 

 the same system, and having sharp bright points at their 

 upper projecting ends, and if the lower portion of the cage- 

 work be well connected with the earth. 



The first condition would be secured in the case of a ship 

 built, rigging and all, of iron, or by a building covered with 

 lead, zinc, or iron, in which all the joints are soldered, and 

 where the metal is continued downwards on all sides, so as 

 to be well buried in the earth. The second condition, by 

 placing over a building a frame-work of iron rod, or wire, 

 so as to have no high or otherwise projecting part of the 

 stone or brick building, above or outside the metallic frame- 

 work, and having t^e framework projecting downwards into 

 the earth at as many points as possible. 



In ordinary buildings, however, it will be generally found 

 more convenient and economical, and almost as effective, to 

 adopt a modification of these arrangements. 



The very essence of a lightning conductor is to afford an 

 easy and wide way for the electricity to reach the earth, for 

 it is only when such way is not present that mischief is 

 done. A thoroughly good and extensive connection with 

 the earth should be the first consideration, for without it 

 all lightning-conductors rather add to than diminish the 

 danger. 



The surface of the earth, if dry, is a bad conductor ; so 

 that a permanently moist stratum is the only one that forms 

 a good earth connection. The sea, a permanent river or 

 creek, a lake, reservoir, or deep well, will all form good 

 earth connections ; all water, or gas-mains under ground, 

 are also equally good earth connectors, and perfectly safe. 



