to-morrow night."

"I'll send you word, just as soon as I get any myself," promised Mr.
Whitford, when he left the next morning.

Tom and Ned spent the day in going over the airship, making some
minor repairs to it, and polishing and oiling the mechanism of the
searchlight, to have it in the best possible condition.

It was about dusk when the wireless outfit, with which the Falcon
was fitted, began snapping and cracking.

"Here comes a message!" cried Tom, as he clapped the receiver over
his head, and began to translate the dots and dashes.

"It's from Mr. Whitford!" he exclaimed, when he had written it down,
and had sent back an answer, "He says: 'Have a tip that smugglers
will try to get goods over the border at some point near Niagara
Falls to-morrow night. Can you go there, and cruise about? Better
keep toward Lake Ontario also. I will be with you. Answer.'"

"What answer did you send?" asked Ned.

"I told him we'd be on the job. It's quite a little run to make, and
we can't start until after dark, or otherwise some of the smugglers
around here may see us, and tip off their confederates. But I guess
we can make the distance all right."

Mr. Whitford arrived at the airship the next afternoon, stating that
he had news from one of the government spies to the effect that a
bold attempt would be made that night.

"They're going to try and smuggle some diamonds over on this trip,"
said the custom agent.

"Well, we'll try to nab them!" exclaimed Tom.

As soon as it was dark enough to conceal her movements, the Falcon
was sent aloft, not a light showing, and, when on high, Tom started
the motor at full speed. The great propellers noiselessly beat the
air, and the powerful craft was headed for Lake Ontario.

"They're pretty good, if they attempted to cross the lake to-night,"
observed the young inventor, as he looked at the barometer.

"Why so?" asked Ned.

"Because there's a bad storm coming up. I shouldn't want to risk it.
We'll keep near shore. We can nab them there as good as over the
lake."

This plan was adopted, and as soon as they reached the great body of
water--the last in the chain of the Great Lakes--Tom cruised about,
he and Ned watching through powerful night glasses for a glimpse of
another airship.

Far into the night they sailed about, covering many miles, for Tom ran
at almost top speed. They sailed over Niagara Falls, and then well
along the southern shore of Ontario, working their wa