“Of course. Why do you ask?”

“Nothing in particular,” replied Mark. But to himself, he added: “That would explain it all.”

It was getting dusk now. The travelers had reached their ship, and rushed inside and tried to close the doors in the face of the advancing horde. But, by this time the giants were so close that one or two of them thrust their big feet in, and prevented this movement. At the same time they set up a great howling.

“Quick!” cried the professor. “We must start the ship and get away!”

“I can’t close the door!” yelled Washington, who had been the last to enter.

“Never mind that! Go up with it open! Drag them along if they won’t let go!” answered Mr. Henderson, as he ran toward the engine room.

There was a sudden rush among the giants, and a sound as if something was being thrown over the top and ends of the ship. Mark turned the gas machine on, while Jack worked the negative gravity apparatus. They waited for the ship to rise.

“Why don’t we go up?” asked the professor.

“'Cause they’ve caught us!” called out Washington.

“Caught us? How?”