CHAPTER XII
FOR A BREATH OF AIR
They could hardly realize it, yet the depth-gage told the story. It registered a distance below the surface of the ocean of five thousand seven hundred feet—a little over a mile. The Advance had actually come to rest on the bottom of the Atlantic.
"Hurrah!" cried Tom. "Let's get on the diving suits, dad, and walk about on land under water for a change."
"No," said Mr. Swift soberly. "We will hardly have time for that now. Besides, the suits are not yet fitted with the automatic air-tanks, and we can't use them. There are still some things to do before we start on our treasure cruise. But I want to see how the plates are standing this pressure."
The Advance was made with a triple hull, the spaces between the layers of plates being filled with a secret material, capable of withstanding
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