454 THE POPULAR SCIENCE MONTHLY. 



calm enjoyment of the belief that rods did protect. The Light- 

 ning-rod Conference had shown, in quite an exhaustive report, 

 that Faraday's position (as opposed to the opinions of Harris) 

 was correct, viz., that the problem was one of simple conductiv- 

 ity ; that a solid rod was better than a tube or tape (which would 

 give greater surface with less copper) ; that solid volume was 

 everything, superficial area nothing ; and that, provided the me- 

 tallic passage afforded the flash was continuous, any flash might 

 be successfully carried off and harmlessly conducted to the 

 ground. 



This conference, while not strictly an official body, was one 

 that, from the character of its members, carried great weight. It 

 was a joint committee of representative members of the Institute 

 of British Architects, the Physical Society, the Society of Tele- 

 graph Engineers and Electricians, the Meteorological Society, 

 and two co-opted members. 



In 1888 came Dr. Oliver J. Lodge's remarkable course of 

 lectures before the Society of Arts upon the oscillatory character 

 of the lightning flash. Then followed the famous dicussion 

 at the meeting of the British Association. As this debate was 

 one in which quarter was neither asked nor given, and the ques- 

 tion at issue was clearly understood by all to be whether a light- 

 ning conductor, when constructed in accordance with the direc- 

 tions of the conference, would absolutely protect, it may not be 

 out of place to give here a synopsis of the arguments advanced. 

 Mr. Preece, who opened the discussion, defined the functions of a 

 lightning conductor as twofold. " It facilitates the discharge of 

 the electricity to the earth, so as to carry it off harmlessly, and it 

 tends to prevent disruptive discharges by silently neutralizing 

 the conditions which determine such discharges in the neighbor- 

 hood of the conductor. To effect the first object, a lightning con- 

 ductor should offer a line of discharge more nearly perfect and 

 more accessible than any other offered by the materials or con- 

 tents of the edifice we wish to protect. To effect the second ob- 

 ject, the conductor should be surmounted by a point or points ; 

 fine points and flames have the property of slowly and silently 

 dissipating the electrical charges; they, in fact, act as safety 

 valves. If all those conditions be fulfilled, if the points be high 

 enough to be the most salient features of the building, no mat- 

 ter from what direction the storm cloud may come, be of ample 

 dimensions and in thoroughly perfect electrical connection with 

 the earth, the edifice, with all that it contains, will be safe, and the 

 conductor might even be surrounded by gunpowder in the heavi- 

 est storm without risk of danger. All accidents may be said to 

 be due to a neglect of these simple elementary principles. The 

 most frequent sources of failure are conductors deficient either in 



