C 54 ] 
About that time great attention was given, and 
many new experiments were made, in confequence 
of the frequent dangerous effects, which lightning 
was obferved to produce in fome valuable buildings, 
by rending and dafhing to pieces very large (tones 
and timbers, which were connected together by- 
cramps and bars of iron : and at other times break- 
ing and melting part of thofe rods, and fometimes 
exploding wires, even of a confiderable thicknefs, like 
fo much gunpowder. 
From careful observations of thefe extraordinary 
appearances produced by violent fhocks of lightning; 
and upon making other experiments relating to a cer- 
tain refitting power in, or upon, all bodies, which ap- 
pears to aft againfi the attacks of lightning, as well as 
againft the eleCtric *fluid, philofophers were enabled to 
affign the reafon, and, it is apprehended, upon a folid 
foundation, why Conductors fhould be made of metal , , 
in preference to all other materials; as the power of 
refitting fuch attacks is lets in metals than in wood, 
(tone, or marble. 
And that this refiftance might be the more fimple 
and uniform, it appeared the moft eligible to have 
the conductors made of one continued piece of me- 
tal only, and of an equal diameter throughout. But 
what that diameter ought to be, depended upon 
other circumftances, fome of which are taken notice 
of in a former paper, referred to above, which I laid 
before the Royal Society. 
By this hitlorical fketch, we fee the propriety of 
Dr. Franklin’s introducing points, and the advantage 
philofophy has derived from them : by afeertaining 
7 that 
