A Guide to the Scientific Knowledge of Things Familiar. Ebenezer Cobham Brewer
and (if a person were touching the bar), the electric fluid passing down it, might run from the bar through the person touching it, and injure him.
Q. Why is it dangerous to be in a crowd during a thunder-storm?
A. For two reasons. 1st—Because a mass of people form a better conductor than an individual: and
2ndly—The vapour from a crowd increases the danger of such a place.
Q. Why is a mass of bodies a better conductor than a single body?
A. Each living body is a conductor of electricity; and a connected mass of such conductors is more likely to be struck, than a single individual.
Q. Why is the danger increased by the vapour which rises from a crowd?
A. Vapour is a conductor, and therefore, may determine the shock; especially when connected with so many living bodies.
Q. Why is a theatre dangerous, during a thunder-storm?
A. Because the crowd assembled there, and the great vapour arising from so many living bodies, render a theatre an excellent conductor of lightning.
Q. Why is a flock of sheep in greater danger than a smaller number?
A. Because each sheep is a conductor of lightning, and the greater the number, the better its conducting power; besides, the vapour arising from a flock of sheep increases its conducting power, and its danger.
Q. Why is a herd of cattle in danger during a storm?
A. 1st—The number of living bodies increases the conducting power of the animal fluids: and
2ndly—The vapour arising from a herd is also a good conductor.
Q. If a person be abroad in a thunder-storm, what place is the safest?
A. Any spot about 20 or 30 feet from some tall tree or building; unless that spot be near to running water.
Q. Why would it be safe to stand 20 or 30 feet from some tall tree, in a thunder-storm?
A. Because the lightning would always choose the tall tree as a conductor, rather than the shorter man; and he would not be sufficiently near the tree, to be injured by the electric current passing down it.
Q. If a person be in a carriage in a thunder-storm, in what way can he travel most safely?
A. He should not lean against the carriage; but sit upright, without touching any of the four sides.
Q. Why should not a person lean against the carriage in a storm?
A. Because the electric fluid might run down the sides of the carriage; and (if a person were leaning against the sides), would make choice of him for a conductor, and perhaps destroy life.
Q. If a person be in a house during a thunder storm, what place is safest?
A. Any room in the middle story. The middle of the room is best; especially if you place yourself on a mattrass, bed, or hearth-rug.
Q. Why is the middle story of a house safest in a thunder-storm?
A. Because (even if the fluid struck the house), its strength would be exhausted before it reached the middle story.
Q. Why is the middle of the room more safe, than any other part of it, in a thunder-storm?
A. Because, if the lightning came into the room at all, it would come down the chimney or walls of the room; and therefore, the further distant from these, the better.
Q. Why is a mattrass bed, or hearth-rug a good security against injury from lightning?
A. Because they are all non-conductors; and, as lightning always takes in its course the best conductors, it would not select such things as these.
Q. Is it better to be wet or dry during a storm?
A. To be wet: if a person be in the open field, the best thing he can do, is to stand about 20 feet from some tree, and get completely drenched to the skin.
Q. Why is it better to be wet than dry?
A. Because the wet clothes would form a far better conductor than the fluids of our body; and, lightning would roll down the wet clothes, without touching our body at all.
Q. What is the safest thing a person can do to avoid injury from lightning?
A. He should draw his bedstead into the middle of his room, commit himself to the care of God, and go to bed; remembering that our Lord has said, “The very hairs of your head are all numbered.”
Q. What is a lightning-conductor?
A. A metal rod fixed in the earth, running up the whole height of a building, and rising in a point above it.
Q. What metal is the best for this purpose?
A. Stout copper wire.
Q. Why is copper wire better than iron?
A. 1st—Because copper is a better conductor than iron:
2ndly—It is not so easily fused or melted: and
3rdly—It is not so much injured by weather.
Q. What is the good of a lightning-conductor?
A. Metal wire is a most excellent conductor; and as the lightning makes choice of the best conductors, it would run down the metal wire, rather than the bricks of the building.
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?
A. Yes; if the rod be not big enough to conduct the whole current to the earth, the lightning will fuse the metal, and greatly injure the building.
Q. How stout is it needful for the copper wire to be, that it may conduct the fluid safely to the earth?
A. It should be (at least) one inch in diameter.
Q. Why does lightning sometimes knock down houses and churches?
A. The steeple, or chimney is first struck; the lightning then darts to the iron bars and cramps employed in the building; and (as it darts from bar to bar) shatters to atoms the bricks and stones, which oppose its progress.
Q. Can you tell me how St. Bride’s Church (London) was nearly destroyed by lightning, about 100 years ago?
A. The lightning first struck the metal vane, and ran down the rod; it then