Through the Earth/Chapter IV
FLORA CURTIS ASKS A QUESTION
"Why, undoubtedly. The attraction of the earth may be considered as coming from the center, may it not?"
"Certainly it may—at least in the present case."
"Well, then," said Mr. Curtis, triumphantly, "it seems to me that if the attraction comes from the center of the earth, the stone would only be pulled down to the center, and would stop there, because there would be nothing to pull it any farther."
"Your idea is to a certain extent correct," replied the doctor; "after the stone reached the center of the earth there would indeed be no attraction to cause it to fall any farther; but you forget that it would then be traveling at considerable speed, and so would not stop."
"Yes, I understand that," said Mr. Curtis; "but as soon as the stone passed the center of the earth, the attraction would begin to pull it from behind, and so would draw it back to the center."
"To be sure, it would pull from behind," laughed Dr. Giles; "but the trouble is, it would n't pull hard enough. If you harnessed a dog to the front of a carriage and a horse at the back, and made them both pull with all their strength, you would certainly not expect the carriage to go forward. No matter how hard the dog might pull, the horse would easily drag him backward."
"I must say that I don't see the connection," observed Mr. Curtis.
"No? Well, then I'll explain. You probably know that a body falling to the earth falls sixteen feet the first second, forty-eight feet the next second, and eighty feet the third."
"Yes, I know that. The speed of a falling body constantly increases, and the increase is about thirty-two feet per second."
"The increase is thirty-two feet per second at the start," corrected the doctor. "As the body neared the center of the earth the increase would become less and less each second, until at the very center of the earth there would be no increase whatever. But, without going into the figures in detail, you will readily see that if the speed of the falling body increased, say, an average of sixteen feet per second, by the time it reached the center of the earth it would be going at such a frightful velocity that it could not stop, but would be carried on right past the center and far up the tube toward the New York end.
"In vain the attraction of the earth would try to hold it back; it would be like the dog pulling against the horse, for the body, carried onward by its acquired velocity, would continue on its mad career, though at a continually decreasing rate, until it came to a stop almost at the very surface of the earth at the New York end of the tube. In fact, if there were no air in the tube, the laws of physics teach us that the body, dropped into the hole here in Australia, would go completely through to the United States!"
"Yes, that 's true enough; but when the body reached the United States, it would simply fall back again, and keep on falling backward and forward in the tube. Moreover, as the air would create a certain resistance to the passage of the body, it would make a shorter journey each time, until finally it came to a complete rest at the center of the earth."
"So it would, if we allowed it to fall back; but you must remember that before it can fall back it must come to a complete stop; and what prevents us from having suitable catches in the tube to hold the body fast and prevent its return! If it stopped short of its destination, as it probably would, it could be hauled up the last part of its journey by any convenient device—say, for example, an electrically actuated cable."
Mr. Curtis was silenced. One by one the objections which had seemed to him so vital vanished into thin air before the doctor's ready answers. He did not for an instant admit the possibility of the scheme, but he was silenced for a moment, and during that moment a third actor appeared upon the scene. This third personage was no other than Mr. Curtis's daughter Flora, a pretty girl of ten, who, curiously enough, far from inheriting her father's pessimism, possessed, on the contrary, the happy faculty of always looking at the bright side of things.
At the beginning of the dialogue above recorded she had been reading unnoticed in a corner of the room; but, little by little, she had become interested in the conversation, and had gradually approached the two speakers. And now, while her father paused, she profited by the interruption to put a question on her own account:
"Dr. Giles," said she, "when you get your hole dug through the earth, will you send only baggage and things like that through it? Won't you send people through as well?"
Mr. Curtis laughed. "I guess nobody would care to go on such a trip as that, Flora," he said.
"I 'm not so sure of that," returned Dr. Giles, drawing the young girl to him, and looking at her kindly. "In fact, I have seriously been thinking of sending passengers through my tunnel."
"What," exclaimed Mr. Curtis, in utter amazement, "you mean to say that you actually think of dropping a living man down a bottomless pit eight thousand miles deep!"
"Yes," said Dr. Giles, "I most assuredly do!"