There was to be no test of the guns this time.  They had worked sufficiently well, and, if need be, could have been fired in the gale.  But Tom did not want his men to take unnecessary risks, nor was he foolhardy himself.

“We’ll have our hands full when we turn around and head into the wind,” he said to his chum.  “That will be enough.”

“Then you’re really going to give the Mars that test?”

“I surely am.  I don’t want any comebacks from Uncle Sam after he accepts my aerial warship.  I’ve guaranteed that she’ll stand up and make headway against a gale, and I’m going to prove it.”

Lieutenant Marbury was told of the coming trial, and he prepared to take official note of it.  While matters were being gotten in readiness Tom turned the wheel over to his assistant pilot and went to the engine-room to see that everything was in good shape to cope with any emergency.  The rudders had been carefully examined before the flight was made, to make sure they would not fail, for on them depended the progress of the ship against the powerful wind.

“I rather guess those foreign spies have given up trying to do Tom an injury,” remarked Ned to the lieutenant as they sat in the main cabin, listening to the howl of the wind, and the dash of the rain.

“Well, I certainly hope so,” was the answer.  “But I wouldn’t be too sure.  The folks in Washington evidently think something is likely to happen, or they wouldn’t have sent that warning telegram.”

“But we haven’t seen anything of the spies,” Ned remarked.

“No, but that isn’t any sign they are not getting ready to make trouble.  This may be the calm before the storm.  Tom must still be on the lookout.  It isn’t as though his inventions alone were in danger, for they would not hesitate to inflict serious personal injury if their plans were thwarted.”

“They must be desperate.”

“They are.  But here comes Tom now.  He looks as though something new was about to happen.”

“Take care of yourselves now,” advised the young aero-inventor, as he entered the cabin, finding it hard work to close the door against the terrific wind pressure.

“Why?” asked Ned.

“Because we are going to turn around and fight our way back against the gale.  We may be turned topsy-turvy for a second or two.”

“Bless my shoe-horn!” cried Mr. Damon.  “Do you mean upside down, Tom?”

“No, not that exactly.  But watch out!”

Tom went forward to the pilot-house, followed by Ned and the lieutenant.  The latter wanted to take official note of what happened.  Tom relieved the man at the wheel, and gradually began to alter the direction of the craft.

At first no change was noticeable.  So strong was the force of the wind that it seemed as though the Mars was going in the same direction.  But Ned, noticing a direction compass on the wall, saw that the needle was gradually shifting.