1883.] 
533 
Origin of Lightning Rods. 
as to save harmless the house or vessel.” And, later on in 
the same letter, he says, “ Metallic rods, therefore, of suffi- 
cient thickness, and extending from the highest part of an 
edifice to the ground, being of the best materials and com- 
plete conductors, will, I think, secure the building from 
damage, either by restoring the equilibrium so fast as to 
prevent a stroke, or by conducting it in the substance of the rod 
as far as the rod goes , so that there shall be no explosion but 
what is above its point, between that and the clouds.” 
Here, at last, we arrive (in the portions we have under- 
lined) at the first mention by Franklin of the theory of the 
conducting action of rods. It is noteworthy that he still, in 
both passages, gives the preventive power of the rod’s point 
the first place ; but he now includes conduction of the ex- 
plosion, after it has occurred, among the functions of the 
rod. The invention was now, however, public property. 
Chiefly through the influence of the great French philosopher 
Buffon, the savants of all civilised countries had by this time 
entertained, discussed, and investigated Franklin’s views. 
He had been in communication with many of them ; and 
we think there is very little doubt that it was principally 
owing to their immature ideas on the nature of electricity in 
general, and on the laws of its aCtion, that this novel and 
unscientific theory, whereby the force evolved by a thunder- 
bolt explosion is treated as if it were a current capable of 
conduction, was harboured by Franklin. 
The fifth, and last, extract we shall make from the writings 
of this eminent man is dated June 29th, 1755, or nearly two 
years later on. He is writing to D’Alibard in regard to Pere 
Beccaria’s views, and he says — “ As to the effect of points 
in drawing the electric matter from the clouds, and thereby 
securing buildings, &c., which you say he seems to doubt , I 
must own I think he only speaks modestly and judiciously. 
I have been but partly understood in that matter. I have 
mentioned it in several of my letters, and, except once, 
always in the alternative, viz., that pointed rods erected on 
buildings, and communicating with the moist earth, would 
either prevent a stroke, or, if not prevented, would conduct 
it, so that the building should suffer no damage. Yet, when- 
ever my opinion is examined in Europe, nothing is considered 
but the probability of those rods preventing a stroke or ex- 
plosion, which is only part of the use I proposed for them ; 
and the other part, their conducting a stroke which they 
may happen not to prevent, seems to be totally forgotten, 
though of equal importance and advantage.” 
The words we have underlined would seem to prove that 
