"Nor a tornado," put in Ross, and he told of Dan'l's death and of his narrow escape with Anton. "I was in the St. Louis tornado," the observer rejoined, and in turn he told of the devastation that had struck the city in 1896.[1] [Footnote 1: While this book was in press a most destructive series of tornadoes visited the United States, Illinois especially suffering. Hundreds of deaths were recorded.] Meantime the thunderstorm was drawing closer and the thunder and the lightning grew gradually nearer. "Do you suppose, sir," asked Tom, "that it would be safe to send up the kite? I've been listening to the hurricane story, and haven't taken the weekly observation yet. Franklin sent up a kite in a storm." "It might be safe, but I wouldn't advise it," answered the Forecaster. "Franklin did it deliberately, for a different purpose, and it was because of his experiment with a kite that we first found out about lightning." "Yes," answered Tom, who knew the story well, "and he collected sparks from the string. But that was a silk string, Mr. Levin. I should think this piano wire would be much worse." "Why?" asked the Forecaster. "On the contrary, it would act as a lightning-rod. Your kite reel is of metal and fastened to the ground. Wire is a much better conductor of electricity than the body, so that there's less likelihood of your being struck." "Is it the difference between a good conductor and a bad one that makes people put up lightning-rods?" asked Fred. "Certainly. All that a lightning-rod does is to convey to the ground the electricity that is about to strike a building. That's the whole system of lightning protection. I can explain it to you fairly well by trees. You know in fairy tales that some trees are supposed to be wicked and other trees are supposed to be good?" "Yes, sir," put in Anton, "Dan'l used to talk about that. He always used to say that the oak tree was a black witch tree and that the beech tree and the alder tree were white witches." "Like nearly all folk-lore," replied the Forecaster, "there's a mighty good reason for that superstition. Folk-lore, after all, is merely keen observation reduced to a saying or a story. It is true that the oak-tree is a black witch so far as lightning is concerned and that the beech and alder are white witches. The proportion of trees struck by lightning has often been counted and for every fifty-four oaks struck, only one beech, or birch, or maple or alder is struck. Elms are fairly dangerous, being forty to the beech's one, and pines are less so, their ratio being fifteen. Not only this, boys, but a good deal depends on the way in which a tree is struck. An oak-tree may be riven into splinters, showing the terrible resistance that it gives to the stroke. A beech-tree, usually, is killed outright, yet shows but little outward injury. The oak has resisted the current, it is a bad conductor; the beech has allowed the current to flow directly to the ground.