1882.] QUESTION BOX. 221 



up. They are very frequently insufficient in size. Lightning- 

 rod men, it is said, sometimes have smooth tongues, and it is 

 also said they sometimes put up too small rods. I have in 

 my possession various specimens of bad rods ; one, for 

 instance, that was put up on the City Hall, I think, in New 

 Haven; it rusted out in a year or two, and was taken down. 

 It was not more than one quarter large enough. I l^elieve 

 there is not a case on record of any iron building ever being 

 injured ; there is not a case on record of a ship that has been 

 properly protected ever l)eing injured. There are innumer- 

 able cases of churches that have been struck over and over 

 again before the days of lightning rods, and never struck 

 afterwards, where the rods have been properly put up. It 

 seems to me that if lightning rods are well put up, they are a 

 protection. It is true that insurance companies generally 

 will make no difference as between buildings that are pro- 

 tected by lightning rods and those that are not, and they 

 make no difference because they cannot know whether the 

 lightning rod men put them up well, or the persons on whose 

 buildings they are put keep them up well afterwards. 



Question. "Will you tell us how to put them up well ? 



Prof. Brewer. In the first place, you want a rod large 

 enough to convey off any charge that may come. If the rod 

 is iron, it should be at least three-quarters of an inch in diam- 

 eter ; if copper, not necessarily so large. A rod one foot high 

 will protect two feet each way. That is on smooth surfaces. 

 If you have a chimney on one end of a house, and you put 

 your lightning rod on the other end, and there is a fire in the 

 chimney, then the lightning rod will not protect it in that pro- 

 portion; the electricity runs down on the warm current in 

 the air. The rod wants to be carried down into moist earth, 

 far enough to be a protection, and buried in some good con- 

 ducting material, like pulverized charcoal. Fifteen years ago, 

 w^hen we proposed to put up lightning rods upon the school 

 with which I am connected, we were visited by divers and 

 sundry agents ; they were very anxious to put up rods for us, 

 because, if it was known that we had employed a particular 

 rod, it would be considerable of an advertisement for it. We 



