SCIENCE 



NEW YORK, APRIL 8, 1892. 



THE NEW METHOD OF PROTECTING BUILDINGS 

 FROM LIGHTNING. 



In April last I read a paper on my new method of light- 

 ning protection, before the American Institute of Electrical 

 Engineers. This paper and the discussion were published in 

 Science of May 8 and 15, 1891. 



In that paper I stated that, simply as a matter of experi- 

 ence, I had failed to find a case on record of any damage by 

 lightning, within certain limits given below, when the con- 

 ductor was destroyed by the discharge. The why and the 

 wherefore of this did not concern me, though of course in- 

 teresting as theoretical questions. 



As no exception was cited at the meeting referred to, and 

 as I could not elicit the citing of an exception through the 

 publication of the article in Science, or of the artiele or ab- 

 stracts of it in the several electrical journals of the country, 

 I began in the issue of Science for June 19, 1891, the regular 

 insertion, which was continued till Feb. 15, 1892, of the fol- 

 lowing: — 



Query. 



Can any reader of Science cite a case of lightning stroke 

 in which the dissipation of a small conductor (one-sixteenth 

 of an inch in diameter, say,) has failed to protect between 

 two horizontal planes passing through its upper and lower 

 ends respectively ? Plenty of cases have been found which 

 show that when the conductor is dissipated the building is 

 not injured to the extent explained (for many of these see 

 volumes of Philosophical Transactions at the time when 

 lightning was attracting the attention of the Royal Society), 

 but not an exception is yet known, although this query has 

 been published far and wide among electricians. 



This has also failed to bring out a single exception to what, 

 so far as I know, is true, that by the destruction of a small 

 conductor all else is saved to the extent named. 



Let me describe here in Franklin's own words a typical 

 case of protection furnished by a small conductor dissipated 

 by the discharge. 



Franklin, in a letter to Collinson read before the Royal 

 Society, Dec. 18, 1755, describing the partial destruction by 

 lightning of a church-tower at Newbury, Mass., wrote: 

 " Near the bell was fixed an iron hammer to strike the hours; 

 and from the tail of the hammer a wire went down through 

 a small gimlet-hole m the floor that the bell stood upon, and 

 through a second floor in like manner; then horizontally 

 under and near the plastered ceiling of that second floor till 

 it came near a plastered wall; then down by the side of that 

 wall to a clock, which stood about twenty feet below the 

 bell. The wire was not bigger than a common knitting- 

 needle. The spire was split all to pieces by the lightning, 

 and the parts flung in all directions over the square in which 

 the church stood, so that nothing remained above the bell. 

 The lighting passed between the hammer and the clock in 



the above mentioned wire, without hurting either of the 

 floors, or having any effect upon them (except making the 

 gimlet-holes, through which the wire passed, a little bigger), 

 and without hurting the plastered wall, or any part of the 

 building, so far as the aforesaid wire and the pendulum-wire 

 of the clock extended ; which latter wire was about the thick- 

 ness of a goose-quill. From the end of the pendulum, down 

 quite to the ground, the building was exceedingly rent and 

 damaged. . . . No part of the aforementioned long, small 

 wire, between the clock and the hammer, could be found, 

 except about two inches that hung to the tail of the hammer, 

 and about as much that was fastened to the clock; the rest 

 being exploded, and its particles dissipated in smoke and air, 

 as gunpowder is by common fire, and had only left a black, 

 smutty track on the plastering, three or four inches broad, 

 darkest in the middle, and fainter towards the edges, all along 

 the ceiling, under which it passed, and down the wall." 



There can be plenty of cases cited of the failure of 

 a large conductor to protect, as is well known to all who 

 have looked into the subject. Of course, all sorts of 

 excuses have been offered for the failure of the ordinary 

 rods, which have been well put by Oliver J. Lodge, F.R.S., 

 who has investigated the electrical problems connected 

 with lightning and lightning protection more than any- 

 one else, and is a complete sceptic as to the efficiency 

 of rods, who says that "when, in spite of all precautions, 

 accidents still occurred ; when it was found that from the 

 best-constructed conductors flashes were apt to spit off in a 

 senseless manner to gun-barrels and bell-ropes, and wire- 

 fences and water-butts, — it was the custom to more or less 

 ridicule and condemn either the proprietor or its erector, or 

 both, and to hint that if only something difl'erent had been 

 done, — say, for instance, if glass insulators iiad not been 

 used, or if the rod had not been stapled too tightly into the 

 wall, or if the rope had not been made of stranded wires, or 

 if copper had been used instead of iron, or if the finials had 

 been more sharply pointed, or if the earth-plate had been 

 more deeply buried, or if the rainfall had not been so small, 

 or if the testing of the conductor for resistance had been more 

 recent, or if the wall to which the rod was fixed had been 

 kept wet, — then the damage would not have happened. Every 

 one of these excuses has been appealed to as an explanation 

 of a failure; but because the easiest thing to abuse has always 

 been the buried earth connection, that has come in for the 

 most frequent blame, and has been held responsible for every 

 accident not otherwise explicable." 



This fact of the complete protection furnished by a dis- 

 sipable conductor stands, therefore, uncontroverted. One 

 very pleasant endorsement comes from Moses G. Farmer, the 

 veteran electrician, who writes: "My experience and obser- 

 vations both confirm his [my] views." 



I repeat, Can any one cite a case of failure, not any theo- 

 retical considerations pro or con, but an actual case of failure 

 under the conditions and to the extent named ? 



N. D. C. Hodges. 



874 Broadway, New York. 



