ON LIGHTNING PROTECTION 237 



fumes of the petroleum. That would not be the case of a powder 

 magazine. The protection in that case could be made perfect. 



It is not necessary to have lightning-rods insulated. Indeed the 

 question is, can we insulate a lightning-rod ? We may insulate it for a 

 small potential, but lightning coming from a mile or two to strike a 

 house is not going to pay any attention to such an insulator; we may 

 just as well nail the lightning-rod directly to the house as far as that 

 goes. 



The idea of having the lightning-rods inclose the bottom as well as 

 the sides of the house is very important, because we do not know, and 

 we have no right to assume, that the earth is a good conductor. We 

 are perfectly certain if the earth forms a good conductor that then the 

 lightning could go down at the sides into the earth. By inclosing the 

 house in a case both below and above we obviate all that difficulty, and 

 it makes no difference whether the earth is a good conductor or not. 



I am glad of this public opportunity to say something with regard to 

 a peculiar form of lightning-rod; it is in reference to a form of a rod 

 shaped like the letter U. I think the idea is that the lightning strikes 

 on one side, and that it goes down and has inertia and flies up again. 

 The company which advocated this idea had the impudence to bring a 

 lawsuit against a scientific man who said it was a humbug. A company 

 of course can make a great deal of trouble to one man; but when there 

 is such a gross humbug as that around, one would like to undergo the 

 danger of a lawsuit. There is nothing scientific about it; it will endan- 

 ger life in any house in which it is placed. 



Mr. SCOTT. I would like to ask whether a building constructed of 

 iron would not be completely protected from lightning ? 



Professor EOWLAND. Yes, if it has a floor of iron too. If a gas-pipe 

 came up into the centre the lightning might find it easier to go across 

 to the pipe than to go around. But if we made a floor of iron the 

 lightning would find it easier to go around than across to the pipe. It 

 must be an entirely inclosed house. 



Mr. SCOTT. Then would not a petroleum tank entirely constructed 

 of iron with an iron bottom be the safest inclosure possible for petro- 

 leum? 



Professor ROWLAND. The peculiarity of that is that the fumes of 

 petroleum are all the time coming out from the cracks. The whole out- 

 side is probably covered with petroleum. I suppose also the ground is 

 saturated with petroleum. The petroleum as far as the inside goes 

 would be perfectly safe. 



