594 KEPORT — 1888. 



mathematical part of the question, first, Ijecause lie did not think it would interest 

 them, and secondly because he did not think he was quite equal to it himself. 



He thouo-ht that this theory, beautiful as it was, of the oscillatory character of 

 a lightning flash must be received with great caution. Now there were several 

 facts against the theory. There is no doubt whatever that electro-magnets are 

 powerfully excited for a sensible dui-ation by lightning flashes. They knew that 

 needles were magnetised and demagnetised ; they knew that electrolysis could be 

 produced by lightning flashes. He had pointed out to them that the mariner's 

 compass was caused to fly about. Sounds were produced. He had stood in the 

 telegraph oflice and he had heard distinctly letters of the alphabet signalled by a 

 flash of lightning. 



Three oscillations were required to make the letter ' R.' He had heard 

 the letter ' C ' which involved four currents. There was a case on record in 

 the ABO instrument of Wheatstone of the letter 'G' having been made. 

 Now the letter ' G ' required eight alternations to be made in order to be 

 recorded. And there were other effects. Hence he said that those durable 

 effects on telegraphs were contrary to the oscillatory theory of the flash, 

 unless the frequency of those oscillations were very small indeed ; and he said that 

 there were very great doubts as to whether it was true for lightning flashes. It 

 might be true for condensers ; it might be true for Leyden jars ; but they were 

 not dealing with Leyden jars ; they were dealing with flashes of lightning, which 

 if they were analogous to anything in a Leyden jar they were analogous to the 

 bursting of the dielectric, and not to the external discharge where oscillations might 

 occur. Of course they had in a Leyden jar the dielectric, with its charges of 

 positive and negative electricity on each side of it in a considerable state of 

 mechanical stress ; and when that stress was suddenly removed, as it was by a spark, 

 then it was not diflicult to conceive that there might be mechanical oscillations in 

 the dielectric ; but he could not conceive that those took place in a flash of lightning 

 which burst tbrough a mere layer of air. Speaking once more upon oscillations he 

 must mention to them that they had evidence, distinct evidence, of slow oscillations 

 in a flash of lightning ; and he thought the photographs would also give tliem some 

 evidence of that. But Professor Elihu Thomson, in America, a very remarkable 

 observer and one of the ablest men on the other side of the Atlantic, had recently, 

 during a thunderstorm, by wagging his head about or wagging his glass about, 

 seen six distinct flashes pass exactly over the same path. They had other evidence 

 in favour of slow oscillations, but at present they had no evidence whatever of those 

 ]'apid oscillations, and if thej' did not exist then the whole of Professor Oliver 

 Lodge's ingenious theory fell to the ground. 



On this point he could not help reading just one little quotation from Faraday's 

 researches, who showed how when a spark flew across an air-space the whole of the 

 electricity disappeared. He said : ' The ultimate effect is exactly as if the metallic 

 wire had been put into the place of the discharging particles, and it does not seem 

 impossible that the principles and action in both cases may hereafter prove to be the 

 same.' lie thought that that statement of Faraday had a most important bearing 

 on tlie theory of electricity. 



He would deal with another and extremely important point that Oliver 

 Lodge had raised, and one of immense value. Mr. Lodge had given some very 

 beautiful experiments indeed to prove his case. He took two Leyden jars 

 and they were charged with a Holtz machine. 



Now there were many objections to this self-induction theory. There was no 

 doubt whatever that Professor Lodge, in this inquiry, had started an entirely new 

 and fresh hare, which they, as electricians, were bound to hunt up, and follow, and 

 kill. lie felt satisfied that Professor Lodge was on the brink of some discovery in 

 connection with static electricity. He did not think his explanations were right. 

 He did not believe in the influence that he assumed of self-induction. 



As a fact ' self-induction ' is used in innumerable senses and in diff'erent 

 ways. Professor Lodge himself, with all his care, could not avoid speaking of this 

 self-induction in various ways. 



Now, as he bad said, Professor Lodge had made a discovery — he (Mr. Preece) 



