208 TKANSACTIONS OF THE AMERICAN INSTITCTE. 



say what or where and also desires his name not to be mentioned, 

 which is an unwise desire, but I will gratify it. His letter, how- 

 ever, suggests two or three questions for discussion, or at least, 

 careful inquiry ; and, perhaps the club will take up the question 

 of lightning rods for discussion at some meeting during the days 

 in which we may expect to hear it thunder. The writer makes 

 the following string of inquiries : 



Does a rod possess power of attraction from the ground to its 

 highest point? or does that part above the building only possess 

 the power of attraction ? and what might be the rule in placing 

 points, as to their distance apart over the ridge of a roof? In 

 many places an idea is prevalent that the rod will protect a cir- 

 cumference of three times its height above the roof. Correct 

 this, if an error. Will a thick rod be more effectual than a thin 

 one the same length ? Will the fluid melt a small rod sooner 

 than a large one ? or, is a thick rod equal or better in every res- 

 pect than a thin one ? If the point should be rusty, would it be 

 worth anything as a conductor ? You could not persuade any 

 farmer that I know to allow a staple to be Avithout a glass or horn 

 for the rod to pass through, for fear of the electricity leaving the 

 rod and passing into the building. Elucidate these points. 

 Should two, three or more points be on one building ? Should 

 they all be connected on the roof with wires ? and should each 

 and every point have a rod extending to the ground, any certain 

 distance from others ? or might they all run down together. Is 

 a solid brass or copper point as good as plated silver or gold ? 

 And is a large point with two or three smaller ones around it of 

 any benefit, all on the same rod ? And, in conclusion, give an 

 explanation of lightning rods suitable for the country. 



I hope some one will prepare succinct answers to these inquir- 

 ies, to be read at some future meeting. 



The Secretary. — The best protection is supposed to be green 

 trees yet barns are often burnt, and the trees left untouched. I 

 should like to know whether lightning rods are really protectors or 

 not. It is a fact that barns are much more frequently struck by 

 lightning than houses, and frequently when there are lightning 

 rods on the building. 



Mr. Cavanach stated that a church in Brooklyn, with several 

 lightning rods, was struck and considerably injured last year. 



This subject will be discussed at a future meeting, and facts 



