Q. How far will the beneficial influence of a lightning-conductor extend?
A. It will protect a circumference all round, the diameter of which is (at least) 4 times as long as that part of the rod, which rises above the building.
Q. Give me an example.
A. If the rod rise 2 feet above the house, it will protect the building for (at least) 8 feet all round.
Q. Why are not lightning-conductors more generally used?
A. Because they are often productive of more harm than good.
Q. How can lightning-conductors be productive of harm?
A. If the rod be broken by weather or accident, the electric fluid (being obstructed in its path) will rend the building into fragments.
Q. Is there any other evil to be apprehended from a lightning rod?