"Well, quite a way from here. I got a telegram about it. Can you get on the job to-night, and do some patrol work along the border?

You're only half a mile from it now. Over there is Canada," and he pointed to a town on a hill opposite Logansville.

"Yes, I can get right into action. What place is that?"

"Montford, Canada. I've got men planted there, and the Dominion customs officials are helping us. But I think the smugglers have changed the base of their operations for the time being. If I were you I'd head for the St. Lawrence to-night."

"I will. Don't you want to come along?"

"Why, yes. I believe I'm game. I'll join you later in the day," Mr.

Whitford added, as Tom told him where the Falcon was anch.o.r.ed.

The young inventor got back to find a bigger crowd than ever around his airship. But Koku and the others had kept them at a distance.

With the government agent aboard Tom sent his craft into the air at dusk, the crowd cheering l.u.s.tily. Then, with her nose pointed toward the St. Lawrence, the Falcon was on her way to do a night patrol, and, if possible, detect the smugglers.

It was monotonous work, and unprofitable, for, though Tom sent the airship back and forth for many miles along the wonderful river that formed the path from the Great Lakes to the sea, he had no glimpse of ghostly wings of other aircraft, nor did he hear the beat of propellers, nor the throb of motors, as his own noiseless airship cruised along.

It came on to rain after midnight, and a mist crept down from the clouds, so that even with the great searchlight flashing its powerful beams, it was difficult to see for any great distance.

"Better give it up, I guess," suggested Mr. Whitford toward morning, when they had covered many miles, and had turned back toward Logansville.

"All right," agreed Tom. "But we'll try it again to-morrow night."

He dropped his craft at the anchorage he had selected in the gray dawn of the morning. All on board were tired and sleepy. Ned, looking from a window of the cabin, as the Falcon came to a stop, saw something white on the ground.

"I wonder what that is?" he said as he hurried out to pick it up. It was a large white envelope, addressed to Tom Swift, and the name was in printed characters.

"Somebody who wants to disguise their writing," remarked Tom, as he tore it open. A look of surprise came over his face.

"Look here! Mr. Whitford," he cried. "This is the work of the smugglers all right!"

For, staring at Tom, in big printed letters, on a white sheet of paper, was this message:

"If you know what is good for you, Tom Swift, you had better clear out. If you don't your airship will burned, and you may get hurt.

We'll burn you in mid-air. Beware and quit. You can't catch us."

"THE COMMITTEE OF THREE."

"Ha! Warned away!" cried Tom. "Well, it will take more than this to make me give up!" and he crumpled the anonymous warning in his hand.

CHAPTER XIII

KOKU SAVES THE LIGHT

"Don't do that!" cried Mr. Whitford.

"What?" asked Tom, in some surprise.

"Don't destroy that letter. It may give us a clew. Let me have it.

I'll put a man at work on that end of this game."

"Bless my checkerboard!" cried Mr. Damon. "This game has so many ends that you don't know where to begin to play it."

The government man smoothed out the crumpled piece of paper, and looked at it carefully, and also gazed at the envelope.

"It's pretty hard to identify plain print, done with a lead pencil,"

he murmured. "And this didn't came through the mail."

"I wonder how it got here?" mused Ned. "Maybe some of the crowd that was here when we started off dropped it for the smugglers. Maybe the smugglers were in that crowd!"

"Let's take a look outside," suggested Mr. Whitford. "We may be able to pick up a clew there."

Although our friends were tired and sleepy, and hungry as well, they forgot all this in the desire to learn more about the mysterious warning that had come to them during the night. They all went outside, and Ned pointed to where he had picked up the envelope.

"Look all around, and see if you can find anything more," directed the custom agent.

"Footprints won't count," said Tom. "There was a regular circus crowd out here yesterday."

"I'm not looking for footprints," replied Mr. Whitford, "I have an idea--"

"Here's something!" interrupted Mr. Damon. "It looks like a lead weight for a deep-sea fishing line. Bless my reel. No one could do fishing here."

"Let me see that!" exclaimed Mr. Whitford eagerly. Then, as he looked at it, he uttered a cry of delight. "I thought so," he said.

"Look at this bit of cord tied to the weight."

"What does that signify?" asked Tom.

"And see this little hole in the envelope, or, rather a place that was a hole, but it's torn away now."

"I'm not much the wiser," confessed Ned, with a puzzled look.

"Why, it's as plain as print," declared the government agent. "This warning letter was dropped from an airship, Tom."

"From an airship?"

"Yes. They sailed right over this place, and let the letter fall, with this lead weight attached, to bring it to earth just where they wanted it to fall."

"Bless my postage stamp!" cried Mr. Damon. "I never heard of such a thing."

"I see it now!" exclaimed Tom. "While we were off over the river, watching for the smugglers, they were turning a trick here, and giving us a warning into the bargain. We should have stayed around here. I wonder if it was Andy's airship that was used?"

"We can easily find that out," said Mr. Whitford. "I have a detective stationed in a house not far from where the Fogers live.

Andy came back from Shopton yesterday, just before you arrived here, and I can soon let you know whether he was out last night. I'll take this letter with me, and get right up to my office, though I'm afraid this won't be much of a clew after all. Print isn't like handwriting for evidence."

"And to think they sailed right over this place, and we weren't home," mourned Tom. "It makes me mad!"