376 PHILOSOPHICAL TRANSACTIONS, [anNO 1773. 



that metals, by being pointed, were rendered still more susceptible of receiving it. 

 And therefore he proposed an experiment to be tried, " Whether it was not in 

 our power to invite, or bring down the lightning, by an apparatus, consisting of 

 an electric stand, and an iron rod, 20 or 30 feet in length, rising upright from the 

 middle of the stand, and at the top, terminating in a very sharp point." This 

 apparatus was recommended to be put on some high building, with the expecta- 

 tion, that if a thunder cloud should happen to pass near this apparatus, some quan- 

 tity of the lightning deposited therein would probably be collected in the rod, by 

 means of the very sharp point, and the electrical stand at the foot of the rod. > 



That this contrivance answered the end he first proposed, we have had sufficient 

 evidence. And it is no wonder if, after this great discovery, we find him, and 

 other electricians, pursuing new experiments of this kind, and raising those 

 points higher into the air, to collect still greater quantities of that fluid which 

 occasions lightning. Nor need we be surprized, after knowing that lightning 

 could be brought down from the heavens by so simple an apparatus, and after 

 experiencing its subtile effects to be similar with the electric fluid, that the 

 Americans, and others, on Dr. Franklin's recommendation, adopted the principle 

 of securing their buildings from its dangerous efl^ects, by raising above their 

 houses rods of iron, very sharply pointed, and applying wires from the ends of 

 those rods, down the outside of their houses to the ground. But though there 

 appeared many arguments at that time in favour of such conductors, yet experi- 

 ments and observations, at last, induced Dr. Franklin to alter his opinion in 

 respect to those wires, and to substitute in their place rods of iron: still retaining 

 the principle of having the rods at the top sharply pointed; and many of the 

 Americans, as well as Europeans, approved of the alteration, as appeared after- 

 wards, from constructing their conductors accordingly. 



About that time great attention was given, and many new experiments were 

 made, in consequence of the frequent dangerous effects, which lightning was 

 observed to produce in some valuable buildings, by rending and dashing to 

 pieces very large stones and timbers, which were connected together Ijy cramps 

 and bars of iron : and at other times breaking and melting part of those rods, 

 and sometimes exploding wires, even of a considerable thickness, like so much 

 gunpowder. From careful observations of these extraordinary appearances, 

 produced by violent shocks of lightning; and on making other experiments 

 relating to a certain resisting power in, or on, all bodies, which appears to act 

 against the attacks of lightning, as well as against the electric fluid, philosophers 

 were enabled to assign the reason, and, it is apprehended, on a solid foundation, 

 why conductors should be made of metal, in preference to all other materials; 

 as the power of resisting such attacks is less in metals than in wood, stone, or 

 marble. And that this resistance might be the more simple and uniform, it 



