It was easy to see that the little hook which hung down from the overlapping works would become engaged with the needle of the compass if the latter were to retrograde in arc 12 degrees 13 minutes.
Unscrewing a cap on the top of the case, he applied a small air-pump, which he had taken out of the box, to the opening, and screwed it firmly on; then, closing the glass door, he placed cement along the junction of the door and sides, from a bottle which he had brought for that purpose. In a few moments, the cement had set, and then, working the air-pump, he soon exhausted the air from the case; finally unscrewing the pump, he replaced the cap and laid the pump in the corner of the chamber.
All this being finished to his satisfaction, he announced that the work for the night was completed.
Looking at his watch, Cobb said:
“It is now four o’clock in the morning, and time that we should get out of this if we don’t wish to be seen departing. We have done all that it is possible to do for the present; let us at once start for town; besides, you have to be at the post by six o’clock.”
“Yes, that is true,” returned Hathaway; “we are due at that hour. We have done a good deal of work, but for the life of me, I am totally ignorant of the purposes of all this apparatus. I would like to have you explain some of it to me,” and his eyes turned inquiringly toward the large case with its wheels and compass.
“All in good time!” and Cobb cautiously opened the swinging panel.
The coast was clear; not a single person was in sight.
“Now, then, be lively!” and he stepped out, the others following quickly. In another moment the door was closed, and not a sign was left to indicate that the pedestal of the Statue of Liberty held within its interior the apparatus necessary for prolonging the life of a human being.