"What do you know about that?" demanded Jack. "'In the name of the law',
no less!"

Professor Henderson jumped to the same conclusion that Mark had, and
that instantly. "It may be the Secret Service men themselves," he said.
"Ah, Andrew! it is just as well to withhold your fire until we know
for sure."

For Andy Sudds had seized his rifle and stood ready to withstand an
attack, should such an act become necessary.

Up from the depths came the cry again:

"Hold your ship. I propose to come aboard and search her. In the name
of the United States Government!"

Mr. Henderson took the radio telephone out of Mark's hand and replied:

"We wish to know who and what you really are. We will not put ourselves
in your power without knowing. We are amply armed."

"Don't you dare to fire upon a United States officer in the discharge
of his duty," cried the voice from below, and now the strange airship
was much nearer to them. "Who do you claim to be?"

"This is the _Snowbird_, from Easton, Maine, She is manned by her
builders, Darrow and Sampson. She carries as passengers Washington
White, Andrew Sudds and Amos Henderson," declared the professor, in
reply. "And she is bound for Alaska."