"And now to see how it works in practice!" cried Tom one day. "Are you with me for a long flight, Ned?"
"I sure am!"
The next evening the Mars, with a larger crew than before, and with Tom, Ned, Mr. Damon and Lieutenant Marbury aboard, set sail.
"But why start at night?" asked Ned.
"You'll see in the morning," Tom answered.
The Mars flew slowly all night, life aboard her, at about the level of the clouds, going on almost as naturally as though the occupants of the cabins were on the earth. Excellent meals were served.
"But when are you going to try the guns?" asked Ned, as he got ready to turn in.
"Tell you in the morning," replied Tom, with a smile.
And, in the morning, when Ned looked down through the plate glass in the cabin floor, he uttered a cry.
"Why, Tom! We're over the ocean!" he cried.