clogged or jammed, and as the pressure outside the ship was so great, the water would not run out of itself. It must be forced.
For an hour or more the inventor, his son and the others, worked away. They could accomplish nothing. Tom looked anxiously at his parent when the latter paused in his efforts.
"Don't worry," advised the aged inventor. "It's got to come right sooner or later."
Just then Mr. Damon, who had been wandering about the ship, entered the engine-room.
"Do you know," he said, "you ought to open a window, or something."
"Why, what's the matter?" asked Tom quickly, looking to see if the odd man was joking.
"Well, of course I don't exactly mean a window," explained Mr. Damon, "but we need fresh air."
"Fresh air!" There was a startled note in Mr. Swift's voice as he repeated the words.
"Yes, I can hardly breathe in the living-room, and it's not much better here."
"Why, there ought to be plenty of fresh air," went on the inventor. "It is renewed automatically."
Tom jumped up and looked at an indicator. He uttered a startled cry.
"The air hasn't been changed in the last hour!"
