614 BEPOKT— 1888. 



miglit be likely to be derived from it. It was very important to observe that there 

 were a number of experiments that bad taken place, especially in connection with 

 some tramway lines, with telegraph instruments and with telephones with eti'ects 

 that had taken place at terminal stations at considerable distances from the 

 lightning which required to be investigated, and about which they knew very 

 little, and which had not been considered vei-y much. 



Mr. Pkeece said he meant to point out what Professor Fitzgerald was now 

 saying, that they had had experience in their telephone exchanges and in their 

 electric light installations where there was a mere metallic conductor, and their 

 experience was that in practice it was exactly what Professor Fitzgerald now 

 referred to, and it was a most interesting point. 



The President said he thought they were all very much obliged to Professor 

 Lodge for his experiment, because heretofore he thought there had been little or 

 no experimental observation of this particular point, and it was a very important 

 thing to them, especially if telephones were likely to become of use ou a large scale, 

 that during thunder storms, if they could possibly do it, they should protect people 

 from injurious effects owing to the presence of the thunder storm, perhaps at a 

 considerable distance from the person that was using the telephone. It was very 

 analogous, it seemed to him, to Professor Lodge's experiments, and they were very 

 much to the point in that connection. lie was inclined to think that the experiment 

 that Professor Lodge had performed was not exactly analogous and in many ways was 

 not at all analogous to a lightning flash. Mr. Preece had called attention to a fact 

 that a lightning flash was very much more like a discharge between the plates of 

 a condenser, much more like the breaking down of the insulation in a Leyden jar 

 when it burst through the glass. Mr. Lodge's experiments had not been on the 

 effect of putting a point upon one of the plates of the air-coudeuser, and if be did 

 make some experiments on it, he thought it would be found there would be a 

 considerable diminution of sparks. 



Professor Lodge : If you have read my paper you will find those experiments 

 have been made too. 



The President said he was afraid he had not studied the thing completely, but 

 the experiments that were alluded to that day were not exactly analogous. 



Professor Lodge : No. 



The President, continuing, said he thought it would have been well if they 

 Lad been told of experiments which were exactly analogous. There was a question 

 with respect to the alternation of currents, and he would call Mr. Preece's attention 

 to this, that even though there might not be millions of alternations per second a 

 great many of the eft'ects of the alternating current would be produced by an 

 extremely sudden current of very short duration. A great many of them would be 

 produced by a single sudden discharge of a millionth of a second. It might be 

 that some of them would not, but a great number of the effects would be, and he 

 thought also a great numter of effects would be produced similar to those that 

 Professor Hertz bad observed, where at a distance from a spark he had observed 

 electro-magnetic effects. Those might also cause electro-magnetic eft'ects in the 

 inside of the house, due to a spark of electricity occurring outside the house. He 

 would like to make one other remark. The globular lightning might possibly be 

 due to the dissociation of the molecules of the air, if there be a region of the 

 air in which there were atoms going about by themselves, combining among them- 

 selves and producing an illuminating part of the air, the original dissociation of the 

 atoms having been produced by some electrical action. 



In conclusion, he thought the principal thing for them to pay attention to was 

 that ' prevention is better than cure.' As M. de Fonvielle had reminded them, 

 there was very little doubt but that the presence of a very considerable number of 

 lightning-conductors undoubtedly affords a great deal of protection to the area 

 within which they exist. M. de Fonvielle had remarked that in the city of Paris 

 they hardly ever had any accidents from lightning. So that it is very desirable 

 that if possible the whole country should be covered with lightning-conductors in 

 order that they might have as many points as possible, and thus, as far as they 

 could, prevent the occurrence of lightning. There was no doubt that when a flash 



