Full in the glare of the powerful beam from the light there was revealed the giant and the man he was pursuing. The latter neither Tom, nor any one on the airship, knew. All they could see was that he was racing away at top speed, with Koku vainly swinging his club at him.

"Bless my chicken soup!" cried Mr. Damon. "Is anything damaged, Tom?"

"No, Koku was too quick for him." yelled the youth, as he, too leaped over the rail and joined in the pursuit.

"Stop! Stop!" called Koku to the man who had sought to damage the great searchlight. But the fellow knew better than to halt, with an angry giant so close behind him. He ran on faster than ever.

Suddenly the stranger seemed to realize that by keeping in the path of the light he gave his pursuers a great advantage. He dodged to one side, off the path on which he had been running, and plunged into the bushes.

"Where him go?" called Koku, coming to a puzzled halt.

"Ned, play the light on both sides!" ordered Tom to his chum, who was now on the deck of the airship, near the wheels and levers that operated the big lantern. "Show him up!"

Obediently the young bank clerk swung the searchlight from side to side. The powerful combined electric current, hissing into the big carbons, and being reflected by the parabolic mirrors, made the growth of underbrush as brightly illuminated as in day time. Tom detected a movement.

"There he is, Koku!" he called to his giant servant. "Off there to the left. After him!"

Raising his club on high, Koku made a leap for the place where the fugitive was hiding. As the man saw the light, and sprang forward, he was, for a moment, in the full glare of the rays. Then, just as the giant was about to reach him, Koku stumbled over a tree root, and fell heavily.

"Never mind, I'll get him!" yelled Tom, but the next moment the man vanished suddenly, and was no longer to be seen in the finger of light from the lantern. He had probably dipped down into some hollow, lying there hidden, and as of course was out of the focus of the searchlight.

"Come on, Koku, we'll find him!" exclaimed Tom, and together they made a search, Mr. Damon joining them, while Ned worked the lantern. But it was of no avail, for they did not find the stranger.

"Well, we might as well go back," said Tom, at length. "We can't find him. He's probably far enough off by this time."

"Who was he?" panted Mr. Damon, as he walked beside Tom and Koku to the airship. Ned had switched off the big light on a signal from the young inventor.

"I don't know!" answered Tom.

"But what did he want? What was he doing? I don't quite understand."

"He wanted to put my searchlight out of commission," responded our hero. "From that I should argue that he was either one of the smugglers, or trying to aid them."

And this theory was borne out by Mr. Whitford, who, on calling the next morning, was told of the occurrence of the night. Koku related how he had found it uncomfortable in his bunk, and had gone out on deck for air. There, half dozing, he heard a stealthy step. At once he was on the alert. He saw a man with a gun creeping along, and at first thought the fellow had evil designs on some of those aboard the Falcon.

Then, when Koku saw the man aim at the big searchlight the giant sprang at him, and there was a scuffle. The gun went off, and the man escaped. An examination of the weapon he had left behind showed that it carried a highly explosive shell, which, had it hit the lantern, would have completely destroyed it, and might have damaged the airship.

"It was the smugglers, without a doubt," declared Mr. Whitford. "You can't get away from this place any too soon, Tom. Get a new hiding spot, and I will communicate with you there."

"But they are on the watch," objected Ned. "They'll see where we go, and follow us. The next time they may succeed in smashing the lantern."

"And if they do," spoke Tom, "it will be all up with trying to detect the smugglers, for it would take me quite a while to make another searchlight. But I have a plan."

"What is it?" asked the government agent.

"I'll make a flight to-day," went on the young inventor, "and sail over quite an area. I'll pick out a good place to land, and we'll make our camp there instead of here. Then I'll come back to this spot, and after dark I'll go up, without a light showing. There's no moon to-night, and they'll have pretty good eyes if they can follow me, unless they get a searchlight, and they won't do that for fear of giving themselves away.

We'll sail off in the darkness, go to the spot we have previously picked out, and drop down to it. There we can hide and I don't believe they can trace us."

"But how can you find in the darkness, the spot you pick out in daylight?" Mr. Whitford wanted to know.

"I'll arrange same electric lights, in a certain formation in trees around the landing place," said Tom. "I'll fix them with a clockwork switch, that will illuminate them at a certain hour, and they'll run by a storage battery. In that way I'll have my landing place all marked out, and, as it can only be seen from above, if any of the smugglers are on the ground, they won't notice the incandescents."

"But if they are in their airship they will," said Mr. Damon.

"Of course that's possible," admitted Tom, "but, even if they see the lights I don't believe they will know what they mean. And, another thing, I don't imagine they'll come around here in their airship when they know that we're in the neighborhood, and when the spy who endeavored to damage my lantern reports that he didn't succeed. They'll know that we are likely to be after them any minute."

"That's so," agreed Ned. "I guess that's a good plan."

It was one they adopted, and, soon after Mr. Whitford's visit the airship arose, with him on board, and Tom sent her about in great circles and sweeps, now on high and again, barely skimming over the treetops. During this time a lookout was kept for any other aircraft, but none was seen.

"If they are spying on us, which is probably the case," said Tom, "they will wonder what we're up to. I'll keep 'em guessing. I think I'll fly low over Mr. Foger's house, and see if Andy has his airship there. We'll give him a salute."

Before doing this, however, Tom had picked out a good landing place in a clearing in the woods, and had arranged some incandescent lights on high branches of trees. The lights enclosed a square, in the centre of which the Falcon was to drop down.

Of course it was necessary to descend to do this, to arrange the storage battery and the clock switch. Then, so as to throw their enemies off their track, they made landings in several other places, though they did nothing, merely staying there as a sort of "bluff" as Ned called it.

"They'll have their own troubles if they investigate every place we stopped at," remarked Tom, "and, even if they do hit on the one we have selected for our camp they won't see the lights in the trees, for they're well hidden."

This work done, they flew back toward Logansville, and sailed over Andy's house.

"There he is, on the roof, working at his airship!" exclaimed Ned, as they came within viewing distance, and, surely enough, there was the bully, tinkering away at his craft. Tom flew low enough down to speak to him, and, as the Falcon produced no noise, it was not difficult to make their voices heard.

"Hello, Andy!" called Tom, as he swept slowly overhead.

Andy looked up, but only scowled.

"Nice day; isn't it?" put in Ned.

"You get on away from here!" burst out the bully. "You are trespassing, by flying over my house, and I could have you arrested for it. Keep away."

"All right," agreed Tom with a laugh. "Don't trespass by flying over our ship, Andy. We also might have a gun to shoot searchlights with," he added.

Andy started, but did not reply, though Tom, who was watching him closely, thought he saw an expression of fear come over the bully's face.

"Do you think it was Andy who did the shooting?" asked Ned.

"No, he hasn't the nerve," replied Tom. "I don't know what to think about that affair last night."

"Excepting that the smugglers are getting afraid of you, and want to get you out of the way," put in the custom official.

That night, when it was very dark, the Falcon noiselessly made her way upward and sailed along until she was over the square in the forest, marked out by the four lights. Then Tom sent her safely down.

"Now let 'em find us if they can!" the young inventor exclaimed, as he made the craft fast. "We'll turn in now, and see what happens 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 way north-east and back again. But not a sign of the smugglers did they see.

Meanwhile the wind had arisen until it was a gale, and it began to rain. Gently at first the drops came down, until at length there was a torrent of water descending from the overhead clouds. But those in the Falcon were in no discomfort.

"It's a bad storm all right!" exclaimed Tom, as he looked at the barometer, and noted that the mercury was still falling.

"Yes, and we have had our trouble for our pains!" declared Mr. Whitford.

"What do you mean?"

"I mean I believe that we have been deceived by a false clew. The smugglers probably had no intention of getting goods across at this point to-night. They saw to it that my agent got false information, believing that we would follow it, and leave the vicinity of Logansville."

"So they could operate there?" asked Tom.

"That's it," replied the agent. "They drew us off the scent. There's no help for it. We must get back as soon as we can. My! This is a bad storm!" he added, as a blast careened the airship.