268 



SCIENCE. 



[Vol. XVII. No. 432 



■faooks say that the ship was saved in spite of the conductor 

 being dissipated. But that is a man's opinion. What I 

 want to urge on the institute is simply this : that in every 

 single case when a conductor goes to pieces every thing else 

 is saved. Why and wherefore, I do not care. I gave some 

 theoretical reasoning which seems to me more or less correct, 

 but it is unimportant. I want to bring the discussion back 

 to simply this matter of fact: Can you cite a case where the 

 conductor has gone to pieces, and there has been any de- 

 struction to the building between practically two horizontal 

 planes passing through the upper and lower ends of that 

 dissipated conductor? You will find that there is damage 

 above and damage below, very likely. But as I went on 

 through the "Philosophical Transactions" I found one case 

 there of a thunder-storm passing over a village (it was a cen- 

 tury ago, or more), and the people were dependent on the 

 church-clock for the time. In the morning they did not 

 hear the clock strike. They went up in the church-tower to 

 see what the matter was, and found the windows smashed 

 just above the bell ; found the wires running from the bell 

 to the clock were gone, and that was all the damage done. 

 To show how small a conductor, when dissipated, will save 

 a house, I will cite the case of a palace in France in the 

 early part of the century. The interior was heavily gilded. 

 The people were sitting around on gilded sofas resting 

 against the walls, — resting against thin gilded strips. A 

 Fellow of the Royal Society visited the palace the day after 

 it was struck by lightning, and looked over the ground. No 

 one was killed. No damage was done to that palace as far 

 as the gilding extended ; that is, in the gilded rooms no 

 damage was done except that the gilding disappeared: it was 

 dissipated. When they got to the lower portions of the 

 palace, where there was no gilding, things were smashed. 

 But, as I say, I started out in this thing with an hypothesis 

 which was to a certain extent wrong. I looked into the 

 records to see what was recorded, not as a matter of opinion, 

 but to find out what actually happened. And what actually 

 happened was, so far as I was able to judge, that there was 

 no case where a dissipated conductor failed to protect a build- 

 ing under these limitations which I state. Of course, above 

 or below, damage did occur. 



A Member: — From a practical standpoint, would you 

 kindly tell us where you put that conductor on a house, and 

 would you put more than one strip on a building ? 



Mr. Hodges: — Along the ridge-pole, down the eaves, down 

 to the ground. I should avoid, at the lower end, making 

 connection with any large masses of metal. The number of 

 strips placed on a building would depend on the size. 



I got a patent on this thing last year. I told a friend of 

 mine that I was interested in the protection of buildings 

 from lightning, and, a patent not being issued, I could not 

 tell him much about it. The next day he met me and said, 

 " Did you read in the Post the account of the lightning- 

 storm in Jersey yesterday?" I said, "No." He said, 

 " There was one case where a house was struck by lightning 

 in Jersey and the rod was smashed, but the house was unin- 

 jured." I noted it down as another case. A man who was 

 in my employ some years ago came to my ofiBce. I described 

 this thing to him, and he said, "I have been there." He 

 said when he was a boy he had a telegraph line running 

 from his house to a neighbor's house. It was made of piano 

 wire, and the lightning struck the roof somewhere there 

 [illustrating], then followed along the metallic gutter to a 

 point here. This piano wire ran down to the ground, and 

 ran over here to the neighbor's house. At this pomt a little 



damage was done to it. The discharge followed along the 

 conductor without doing any material damage, and there 

 was no other damage to the house except that the wire was 

 gone. 



Mr. Wolcott: — Although I do not question that conduc- 

 tors work that way, we also find that they work the other 

 way, according to the old theory, in very many instances. 

 It certainly is a matter of record that conductors have some- 

 times carried off several discharges m the same thunder- 

 storm, which a dissipatable conductor could not do unless 

 you were able to put up a second one in the place imme- 

 diately after the dissipation of the first. 



A Member: — The Washington Monument is a pretty good 

 lightning arrester. I was shown, a few weeks ago, by Pro- 

 fessor Owens, where lightning had struck and knocked out 

 big chunks of stone from the monument. He seemed to 

 think that lightning followed the path of least electrical re- 

 sistance, so he put up an additional wire and connected that 

 with the new iron work of the monument, and he says he 

 has not had any trouble since then with stones being knocked 

 out. 



Mr. E. P. Thompson: — I have not heard of any experi- 

 ments being performed upon Mr. Hodges' proposed system. 

 It may seem, perhaps, impossible to perform experiments 

 with lightning in a laboratory, because of the inconvenience 

 of waiting for a thunderstorm; but it can be done with the 

 induction system, and possibly, therefore, some way may be 

 thought of for testing Mr. Hodges' invention. About three 

 years ago I tried some experiments in connection with a 

 client, a well-known lightning-rod manufacturer, Capt. 

 Hubbell, who has equipped government magazines. His new 

 system was tried with considerable elaborateness in the 

 Equitable Building during its repair, for the consideration 

 of the Standard Oil Company, who met with great losses of 

 oil-tanks, caused by lightning. An immense Leyden battery 

 was charged with an electrical friction machine, and arti- 

 ficial lightning was thus generated. Small oil-tanks con- 

 taining alcohol — more easily lighted by the spark than 

 petroleum — were equipped, and by discharging the battery 

 it was easily determined how many times out of a hundred 

 the Captain's system was successful. Some experiment with 

 Mr. Hodges' system would soon settle the question of effec- 

 tiveness. 



Mr. Charles Steinmetz: — To one point more I wish to 

 draw attention. By using such an interrupted conductor of 

 small cross-section, that is of comparatively high resistance, 

 you are liable to change the whole nature of the lightning 

 discharge. You change it from an oscillating discharge to a 

 steady and continuous rush of current, from which you must 

 expect quite different effects. 



When, for instance, you discharge a condenser by a con; 

 ductor of very low resistance, you get an oscillating discharge 

 of an extraordinary high frequency. If you increase the 

 resistance of the conductor, the number of oscillations of the 

 discharge decreases, it runs down quicker, until at last you 

 reach a value of resistance where only one wave of discharge 

 current appears, that is, the discharge of the condenser be- 

 comes steady. Now, if we can make a lightning discharge 

 steady, instead of oscillating, then we have first to expect 

 that the electricity traverses the lightning-rod only once, 

 slowly increasing in current strength and then decreasing 

 again by going down to the ground ; while in an oscillating 

 discharge the current will rush to and fro through the con- 

 ductor until its energy is consumed by the resistance of the 

 lightning-rod, or by electro-magnetic radiation and re-radia- 



