"A man named Bainbridge is at their head. He was originally a diamond
dealer and finally was caught smuggling gems into the port of New York.
He had to pay a huge fine and served a term at Atlanta for that crime
and since then has sworn to be revenged upon the Government that
punished him.

"We learned of late that he was operating on the Mexican
border--bringing into the States diamonds that had paid no duty--by
aid of a flying machine. But the uprising in Chihuahua and along the
border made his work exceedingly dangerous, and he was driven away
from that part of the country.

"Now we believe he has joined forces hereabout with ancient enemies
of the Federal officers. At least, there is a strange aeroplane reported
from both sides of the border, and some fine gems have appeared in the
hands of certain suspected dealers in Maine, and as far south as Boston
and Providence.

"Bainbridge is known to be a desperate man. Look out for him, Professor.
If you are hailed by another machine, better keep away from it," and
the secret service agent laughed. "Had I been in your place I would
not have halted on this occasion. You certainly can outsail any airship
I have ever seen operated."

Mr. Ford seemed quite satisfied that our friends were law-abiding and
he ascended to his waiting craft in a few moments; and the _Snowbird_
started onward again through the starlight.

But the warning of the special agent had impressed the boys as well