just over the house—directly overhead. An instant later he knew what it was.
"The motor of an aeroplane, or a dirigible balloon!" he exclaimed. "Some one is flying overhead!"
For an instant he feared lest the shed had been broken into, and his Humming-Bird taken, but a glance toward the place seemed to show that it was all right.
Then Tom hastily made his way to where a flight of stairs led to a little enclosed observatory on the roof.
"I'm going to see what sort of a craft it is making that noise," he said.
As he opened the trap door, and stepped out into the little observatory the sound was so plain as to startle him. He looked up quickly, and, directly overhead he saw a curious sight.
For, flying so low as to almost brush the lightning rod on the chimney of the Swift home, was a small aeroplane, and, as Tom looked up, he saw in a light that gleamed from it, two figures looking down on him.
