"Well, well!" exclaimed the voice of their pursuer. "That may all be
so. But I have my suspicions. I am Ford, special agent of the Department
of Justice. Stand by. Now I am coming aboard."

At a nod from the professor, Mark had already brought the _Snowbird_ to
a halt. She lay floating, with all planes extended and without motion of
propellers, poised over the summit of Mt. Katahdin.

The descending moon threw its beams over the height and revealed to
the vaguely anxious occupants of the _Snowbird_, the other machine
darting up from below.

This was a craft of much different aspect from their own. It was a
great deal smaller and apparently without half the power possessed by
the one built by Jack and Mark.

She shot into the air above their heads at a swift pace, however, and
immediately poised over them. In this attitude Ford, as he called
himself, had the occupants of the _Snowbird_ completely at his
mercy. A bomb dropped upon the huge flying machine would have blown
her to pieces. Or, with a gun, he could have picked off one after
another of the five people below.

"Stand out of the way, there!" commanded Ford.

Instantly those upon the larger air-craft saw a figure swing down from
the framework of the airship above their heads. A light rope ladder
unrolled and fell upon the upper deck, or platform of the _Snowbird_,
and the man came down this ladder, hand under hand, and in half a minute
stood in their midst.