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vO elilON | BRON LiCGHRNIUNG. 
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 ? 
Ts 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 
sts inthe column of dielectric (mainly air) extending from the cloud to the 
known that this energy e) 
earth? Do we not know since Lord Kelvin’s experiments that this energy exists in the air on account of 
inch, and that conse- 
a state of electrical stress, which stress cannot exceed .0075 of a pound per square 
quently the amount of energy in each cubic foot of air cannot exceed about one foot-pound ? 
just before the flash exists in the column of air between the cloud and the 
Knowing that the ene 
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 
i 
call a flash of lightning, is it not evident that the energy miust be transmitted in lines perpendicular to 
I 
in the main horizontally, indicated in the figure by the arrows? 
the lines of electrical stress, 
From all this, which is a part of our current knowledge, it appears that the problentof 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 involved in a flash of lightning, 
pated as heat above the roofs of our houses. If the conditions can be so 
by far the larger part being di 
arranged, by the use of considerable masses of metal suitably placed, that there shall be no state of stress 
below the roof of the hcuse, then there will be no energy to be dissipated below that level, and all will go well. 
li 
| 
Tut 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 
lt 
way but must be dissipated in some harmless manner. 
The deflagration of a pound or two of thin copper ribbon dissipates a large amount of energy, 
i ~ “e 3 : a ———_ 
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. his lightning protector, manufactured under* patents of N. D. C. SSS 
sare fh ‘ : 5 : : SSS 
Hodges, Editor of Scvence, is sent prepaid to any address on receipt of $5.00 per 100 fect. The amount 
: = e . . . } vy — 
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 feet. Any carpenter can put it on. 
oe 
PROTECTION COMPANY, 
874 BROADWAY, NEW YORK. 
