VOL. LIV.] PHILOSOPHICAL TRANSACTIONS. 143 



pounds was removed 50 yards eastward from the steeple, where it fell through 

 the roof of a house. It is evident that these effects would have been prevented, 

 if a sufficiently large metallic conductor had been extended from the metal at the 

 top of the spire down to the earth, communicating with the other metallic parts 

 of the building that lay in its way. Such a communication seems very necessary 

 in buildings of this form. The iron bars which were fixed in the stone-work, of 

 the east arches, were struck, by the lightning, while those in the arches fronting 

 them on the west side of the same story remained untouched by it. So that 

 probably a conductor communicating with the west arches only, would not have 

 preserved the opposite ones from the damage they have suffered. 



When such buildings are exposed to very large clouds replete with lightning, 

 there is no reason to imagine that they will not convey soqie of their contents to 

 other metallic parts of the building at the same time as to the metal at the top: 

 for though the conductor may be large enough to convey to the ground, from 

 the top, all the lightning that enters that part ; yet one such small conductor 

 cannot be supposed to exhaust those immense bodies so quickly, as to disable 

 them from striking at the same time other buildings, or other parts of the sarpe 

 building. A wire, or very small rod of metal, does not seem to be a canal 

 sufficiently large to conduct so great a quantity of lightning to the earth ; espe- 

 cially when any part of it, or of the metal communicating with it, is inclosed 

 in the stone-work : in which case, the application of it would tend to increase 

 its bad effects, by conducting it to parts of the building which it might other- 

 wise not have reached. 



Dr. Franklin, from observing that the filleting of gold leaf on the cover of a 

 book conducted the charge of 5 large jars, reasons that a wire will be sufficient 

 to conduct the lightning from the highest buildings to the earth. But it appears 

 from an experiment of his own, that a much larger body of metal, when in- 

 closed between small plates of thick looking glass, is not sufficient to conduct a 

 5th part of such a charge, without being melted, and bursting to pieces the 

 plates of glass. And it is remarkable, that in those parts of the church where 

 the effects of the lightning are most conspicuous, the iron was inclosed in a 

 resisting substance similar to the glass surrounding the gold leaf in that 

 experiment. Wires, instead of conducting the lightning, have often been 

 melted by the explosion. So that, it seems a conductor of metal less than 6 or 

 8 inches in breadth, and a quarter of an inch in thickness (or an equal quantity 

 of metal in any other form tliat may be found more convenient) cannot with 

 safety be depended on, where buildings are exposed to the reception of so great 

 a quantity of lightning. These are the only points in which I have ventured to 

 differ from Dr. Franklin. 



