tion of gravitation, as all the objects in the car were falling with precisely the same speed, they ought to weigh absolutely nothing during any part of the journey!
But it was now plainly manifest that bodies in the car did have weight, a weight equal to one eighth of what they possessed upon the earth, and this weight was steadily increasing every minute!
Here was indeed a puzzle. William that morning was firmly convinced that during his fall through the earth all bodies in the car would at the start have their normal weight, but that at the center of the earth none of them would weigh anything at all.
Yet, in practice, what had occurred? The very reverse of what he had imagined. At the start, none of the bodies in the car possessed any weight, while here, as he approached the center of the earth, they were in some mysterious manner rapidly regaining their heaviness.
Then he remembered the doctor's words, and the explanation came back to him like a flash. Evidently this resumption of weight was due to the presence of air in the tunnel. The doctor had not been able to remove all the air from the tube, and what little was left sufficed to retard the car
