TRANSACTIONS OF SECTION A. 471 



passed very powerful charges of electricity through them, observing their thermic 

 eifects upon platmum and silver wires. It was found that change of form pro- 

 duced no difference whatever in the character of the discharge, and it was proved 

 that the discharges of electricity of high potential obey the laws of Ohm. No 

 more efficient lightning conductor can be devised than a cylindrical rod or a wire 

 rope. 



9. On the necessitij for a regular Inspection of Lightning Conductors. 

 Bij Richard Anderson, F.G.S., A.Inst.G.E. 



The author referred to a paper by M. W. de Fonvielle, ' On the advantage of 

 keeping records of Physical Phenomena connected with Thunderstorms,' read 

 before this Association in 1872. M. de Fonvielle recommended to the attention of 

 the members the steps which had been taken by the French Government for 

 obtaining information regarding thunderstorms, and suggested that the Association 

 should institute some organisation for the collection of such data; arguing that it 

 would be of much value to science, as well as to the public. Nothing, however, 

 has been done by the Association since 1872 ; and the author not only confirmed 

 the conclusions at which M. de Fonvielle arrived as to the desirability of collecting 

 such data, but was of opinion that the organisation should go further, and arrange 

 for a regular inspection of all public buildings which had lightning-conductors 

 applied. 



The necessity for this he demonstrated by adducing a number of striking cases 

 where damage, more or less severe, had occurred to buildings, even though having 

 lightning conductors attached to them. The cases now cited, he explained, were 

 supplementary to those communicated in his paper on a similar subject to the 

 Association in 1878. A few of the cases were as follows : — 



In October, 1878, an elevated building situated at the back of Victoria Station, 

 occupied as a furniture repository, was struck by lightning and sustained damage, 

 although furnished with a f-inch by ^-inch copper-band lightning conductor and 

 a tube of |-inch diameter rising above the iron crestings on tower. The lightning 

 shattered the cresting and bent the point of the lightning-rod, besides doing other 

 damage to the building. On testing, the author found the resistance very great, 

 and on opening out the earth-terminal found it embedded in concrete. 



In June last St. Mark's Church, Skelton, was struck by lightning, when the 

 air-terminal of a f-nich diameter copper-rope conductor was slightly bent. On 

 testing, the author found the resistance great, and on opening the ground, the 

 conductor was found to be carried from the building about 14 feet and bxiried 

 among brick and stone rubbish. The conductivity of the copper was 52 50 instead 

 of 92 to 94 per cent. 



On June 26 last lightning struck All Saints' Church, Lambeth, doing con- 

 siderable damage, although there was a f-inch diameter copper-rope conductor on 

 the west gable, with a copper tube rising 18 inches above. A stone cross about 50 

 feet from the conductor was thrown down, injuring the roof of the north aisle. 

 On testing the conductor, the author found that it had no ' earth ' whatever, the 

 rope being simply placed in 2 inches of loose rubbish. The copper was of very 

 inferior quality; conductivity being 32'10 per cent., or about double that of iron. 



The author quoted also a few cases fi-om his recent work on ' Lightning Con- 

 ductors, their History, &c.' : — 



In August, 1878, the Powder Magazine at Victoria ColHery, Burntcliffe, York- 

 shire, was struck by lightning, though furnished with a conductor 13 feet above 

 the building and terminating in 13 feet of clayey soil. The building was blown to 

 pieces. On testing the conductivity of the copper it was found to be 39'2, instead 

 of 92 to 94 per cent. The conductor was insulated from the building and from a 

 large iron door, which it ought not to have been. 



The author concludes from this evidence that it is not sufficient merely that 

 rods of copper should be attached to a building, but it is necessary that after being 

 fixed they should be regularly inspected, to see if they are in good order, so as to 

 be really efficacious. 



