532 THE APPLICATIONS OF PHYSICAL FORCES. [BOQKV. 



and against this method, prove that it is far from being certainly 

 efficacious. It is not even proved that it has ever had any influence 

 at all in dispersing clouds, and one might just as easily deduce the 

 opposite conclusion from the facts stated. 



The same must be said of the ringing of bells. The practice of 

 setting the church bells ringing during storms has no other origin 

 than in superstition, and the most certain effect of the practice of it 

 is to make the ringers run a real danger, in order to ward off a much 

 smaller one by imaginary means. Lightning, in fact, strikes by pre- 

 ference the highest objects, especially those which, like bell towers, 

 are almost always surmounted by insulated metal. 



Since the time of Franklin, who was, as is well known, the inven- 

 tor of lightning-conductors, science can recommend no other means of 

 preserving edifices and houses with their inhabitants from lightning 

 than these simple and almost always sufficient apparatus, provided 

 they be constructed and set up in such a way as experience and theory 

 unite in regarding as correct. 



The lightning-conductor is an application of the power possessed 

 by metallic points of discharging the electricity from bodies in their 

 neighbourhood, and the idea of making use of this property, which the 

 illustrious American physicist had lately discovered, was the natural 

 consequence of his opinion on the identity of lightning and thunder 

 with electrical phenomena. The experiments which proved- this 

 identity were made almost simultaneously, in 1752, in America and 

 in France, Franklin flying in that year his famous kite, armed with a 

 point, and .drawing sparks from a thunder cloud near Philadelphia, 

 whilst the French physicist Dalibard verified at the same time the 

 ideas suggested by Franklin by setting up an insulated bar of iron 

 fourteen metres high in the plain of Marly- en -ville. 



Shortly afterwards the first lightning conductors were fixed at 

 Philadelphia. From America they quickly passed to Europe, and 

 the first one seen in France was fixed at Dijon by Guy ton de Morveau. 



The most recent 1 instructions on the employment and construc- 



1 The first report upon this interesting question dates from 24th of April, 1784, 

 and the commission which drew it up numbered among its members Coulomb, 

 Laplace, and Franklin himself. 



In 1799, 1823 and 1855, new instructions were given and submitted to the appro- 

 bation of the Academy of Sciences. 



