PROTECTION FROM LIGHTNING. 457 



There was a certain amount of energy which they must dissipate 

 somehow, and they could not expect to hocus pocus it out of exist- 

 ence by saying they could conduct it to the earth. The quicker 

 they tried to conduct it down to the earth the more searching 

 and ramifying disturbances they were likely to get. It might be 

 better to let it trickle down slowly by using a moderately bad 

 conductor than to rush it with extreme vehemence down a good 

 conductor, just as it would be safer to let a heavy weight sus- 

 pended in a dangerous position down slowly rather than let it 

 drop as quickly as possible. ... If a man holds a lightning con- 

 ductor when a flash passes down it, he will most likely be killed. 

 ... It did not matter about the earth ; . . . a spark was likely to 

 occur ... he had made experiments in the laboratory with a 

 rod very thick and a yard long, in circuit with a Ley den- jar dis- 

 charge. He took a platinum wire as fine as possible to make the 

 contrast greater, and arranged it so as to make a kind of tapping 

 circuit ; if, then, the bottom end was arranged so as to be in con- 

 tact with the rod and then let the top end be an eighth of an inch 

 away, then they would have a splendid conductor, better than any 

 lightning conductor ever was. They would have no trouble about 

 earth. It seemed absurd for any portion of the discharge to leave 

 this conductor to jump across and make for the little strip of 

 wire. Nevertheless, a portion of it did, and from every spark that 

 went to the conductor, a side branch went to that little wire. . . . 

 What are the conditions of a flash ? He assumed that a flash be- 

 haved like experiments in the laboratory, but it was a ques- 

 tion whether a cloud discharge was of this kind. A cloud is not 

 like a conductor ; it consists of globules of water separated from 

 one another by interspaces of air ; it may be compared to a span- 

 gle jar : when a spangle jar discharges, you have no guarantee 

 that the whole of it discharges it discharges in a slowish manner. 

 It might be that there was with a cloud first a bit of a discharge 

 and then another bit, and so on, so that there might be a kind of 

 dribbling of the charge out of it, and they might therefore fail to 

 get these sudden and oscillatory rushes. . . . But we must pro- 

 vide for the possibility of a sudden discharge." 



Hon. Ralph Abercromby contributed to the discussion facts 

 brought out by an examination of some ninety photographs of 

 lightning flashes in different parts of the world. In one in- 

 stance the whole air was filled with threads of lightning coming 

 down like the roots of a tree from the sky. He thought it was 

 very much a question where the area of protection would be when 

 the whole air seemed to be pouring lightning down upon you. 

 He would also like to find out whether buildings were struck 

 during rain or when it was not raining. In connection with the 

 fact that thunderstorms were confined to the lower ten thousand 



