port the boy. Even though there were no air whatever in the car, if the boy were half-way between the floor and ceiling when the car began to' fall, he would still remain suspended in space."
"But why is it he would n't fall?" asked Flora, not altogether able to understand the matter.
"He would fall," said the doctor; "that is to say, he would fall toward the center of the earth. But the car would be falling, too, so he would remain suspended half-way between the floor and ceiling of the car."
"I must be awfully stupid, but I don't quite understand it yet."
"Well, listen, Flora. Suppose I were to drop a stone down through my tunnel, and were immediately afterward to let another stone fall after it. Would the second stone ever catch up with the first?"
"No, of course not. The first one would be falling just as fast as the second one, and as it started before the other, the second one could never catch up with it."
"Exactly," said Dr. Giles, triumphantly. "Now, suppose I let the bottom of the car fall through the earth first, and then a second later drop William through; could he ever catch up with it?"
