226 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



there is an excess of fluid in the air around the top of a rod, it 

 will run down it to the earth, just as it runs along telegraph 

 wires ; and experience has proved that a bright sharp point is 

 more attractive than a blunt one. 



Still, a blunt rod will become charged, and so will a metal roof, 

 and, more than all, an iron building, and the water conductor, or 

 whatever other metallic substance reaches from the top to the 

 earth, will tend to dissipate the excess of electricity in the air 

 above and around the building, and prevent an accumulation of 

 it sufficient to produce an explosion. But I have not one par- 

 ticle of faith that any building that happened to be situated in 

 the path of what we call a thunderbolt, ever w^as saved by the 

 best lightning rod ever erected. And if in its course the dis- 

 charge from the cloud, coming like a rifle ball from the muzzle 

 of the gun, happens to strike the sharp point of the rod, it is to 

 my mind a preposterous idea to suppose that perfect insulation 

 of that rod from the building can be of any possible advantage. 

 Thus far had I written, when the September number of The 

 Working Farmer accidentally was taken up, and the first thing 

 that attracted my attention was an article under the head " Pro- 

 tection from lightning." From this I make a few extracts perti- 

 nent to the subject. The writer says : 



" There can be few subjects of equal importance less generally 

 understood, or perhaps more universally misunderstood, than 

 the science of electricity in its application to lightning rods. 

 The errors of the past are very slow of eradication, although it 

 must be admitted that progress has been made since the famous 

 discussion in George III.'s time, as to whether lightning rods 

 should be pointed or blunt at the top. So little is known of 

 electricity itself, and so largely is it a purely speculative science, 

 that it is no wonder that doctors disagree. 



"It is clear that the most valuable opinion on this subject is to 

 be looked for from those who have made the study of electricity 

 and thunder-storms a specialty, with the practical result in view 

 of ascertaining the most eifectual means of protection, and it is 

 to be remarked that those who havo done this, have arrived at 

 similar conclusions. 



" It is a common error to suppose that lightning rods should 

 130 insulated, and a very natural one, arising from a superficial 

 view of the subject. It should be remembered that currents of 

 electricity in a rarified state are continually circulating through 



