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| PrOmeGhi@N -2ROM  LiGhHiNING: 
S it not true that, in a vague way, the usual conception of the cause of damage by lightning is that 
something (in past ages a “‘ thunderbolt’) comes down from the thunder cloud to do the damage ? 
Is it not true that since damage is done by lightning we should seek the mass of matter in which 
this energy must exist just before the flash? Js it not equally true that since Faraday’s time we have 
known that this energy exists inthe column of dielectric (mainly air) extending from the cloud to the 
earth? Do we not know since Lord Kelvin’s experiments that this energy exists in the air on account of 
a State of electrical stress, which stress cannot exceed .0075 of a pound per square inch, and that conse- 
quently the amount of energy in each cubic foot of air cannot exceed about one foot-pound ? 
Knowing that the energy just before the flash exists in the column of air between the cloud and the 
earth, which column is indicated in the figure by the dotted lines, and that when the air ‘‘ breaks down”’ and 
the flash comes this energy manifests itself mainly as heat along the central core of this column in what we 
eall a flash of lightning, is it not evident that the energy must be transmitted in lines perpendicular to 
the lines of electrical stress, z.c., in the main horizontally, indicated in the figure by the arrows ? 
From all this, which is a part of our current knowledge, it appears that the problem of protection from 
lightning is a problem in the dissipation of energy ; that the energy to be dissipated, while we know it to be 
considerable, as broken masonry testifies, is but a small part of the whole inyolved in a flash of lightning, 
by far the larger part being dissipated as heat above the roofs of our houses. If the conditions can be so 
arranged, by the use of considerable masses of metal suitably placed, that there shall be no state of stress 
below the roof of the house, then there will be no energy to be dissipated below that level, and all will go well. 
But it is surely time that the problem of protecting buildings from lightning should be looked upon as one 
in energetics and that it should be appreciated that the energy present cannot be hocus-pocussed out of the 
way but must be dissipated in some harmless manner. 
The deflagration of a pound or two of thin copper ribbon dis: 
how much we do not know, but experience shows it isso large that too little is left to do other damage when 
a house is struck by lightning. This lightning protector, manufactured under patents of N. D. C. 
Hodges, Editor of Sczence, is sent prepaid to any address on receipt of $5.00 per 100 feet. The amount 
ordered should be sufficent to run lines of the protector from the highest to the lowest points of the build- 
ing, at intervals of about forty fect. Any carpenter can put it on. 
ipates a large amount of energy, 
AMERICAN ]_IGHTNING 
PROTECTION COMPANY, — 
874 BROADWAY, NEW YORK, ~ 
