In a short time they had circled the great mass of ice. They all fully realized now how cold it was, and why the sea water must be affected for a mile or more all around such a tremendous bit of the Arctic regions.
They found that most of the floe lay on the north side of the berg; and decided that their best chance for landing must be in that quarter.
"The old berg looks top-heavy," Jack at one time called out. "You can see that it leans toward the north; and sometimes I've thought it wobbled considerably, though that may have been the plane waving up and down."
"No, you were right, Jack," said Beverly. "Its leaning that way tells that the warmer sea water has begun to eat at its base. Before a great while the berg will roll over, and smash all that floe into bits."
"I hope not when we're on it, working at our motor!" Jack could not keep from exclaiming, looking with more interest than ever at the monster berg that had come all this distance from some glacier a thousand miles away, perhaps several times that distance, and would sooner or later lose itself in sub-tropical waters.
Lower still Tom took them. All eyes continued to survey the field of ice, particularly in that extreme northern sector where Jack had reported lay the best place for landing.
"Once more in a circle so as to face the wind," said Tom, "and then I mean to put it to the test."
"Good luck to you, Tom!" said Jack. "If ever you dropped as if you were falling on eggs, let it be now. I'm going to hold my breath when we strike the ice, and only hope we don't keep gliding along until we shoot off the edge into the sea!"
"Leave that to me, Jack," came the assurance of the pilot.
After that no one said a word, for both Lieutenant Beverly and Jack Parmly realized that it would be dangerous to distract Tom's attention from his work just at the most critical moment.