“Good!  And I hope you’ll catch the rascals!” fervently exclaimed the custom official.  “Well, Tom, I’m leaving it all to you.  Here are some reports from my deputies.  I’ll leave them with you, and you can look them over, and map out a campaign.  When you are ready to start I’ll see you again, and give you any last news I have.  I’ll also arrange so that you can communicate with me, or some of my men.”

“Have you given up all suspicion of the Fogers?” asked the young inventor.

“Yes.  But I still think Shopton is somehow involved in the custom violations.  I’m going to put one of my best men on the ground here, and go to the border myself.”

“Well, I’ll be ready to start in a few days,” said Tom, as the government agent departed.

For the next week our hero and his chum were busy completing work on the great searchlight, and in attaching it to the airship.  Koku helped them, but little of the plans, or of the use to which the big lantern was to be put, were made known to him, for Koku liked to talk, and Tom did not want his project to become known.

“Well, we’ll give her a trial to-night,” said Tom one afternoon, following a day of hard work.  “We’ll go up, and flash the light down.”

“Who’s going?”

“Just us two.  You can manage the ship, and I’ll look after the light.”

So it was arranged, and after supper Tom and his chum, having told Mr. Swift were they were going, slipped out to the airship shed, and soon were ready to make an ascent.  The big lantern was fastened to a shaft that extended above the main cabin.  The shaft was hollow and through it came the wires that carried the current.  Tom, from the cabin below, could move the lantern in any direction, and focus it on any spot he pleased.  By means of a toggle joint, combined with what are known as “lazy-tongs,” the lantern could be projected over the side of the aircraft and be made to gleam on the earth, directly below the ship.

For his new enterprise Tom used the Falcon in which he had gone to Siberia after the platinum.  The new noiseless motor had been installed in this craft.

“All ready, Ned?” asked Tom after an inspection of the searchlight.

“All ready, as far as I’m concerned, Tom.”

“Then let her go!”

Like a bird of the night, the great aeroplane shot into the air, and, with scarcely a sound that could be heard ten feet away, she moved forward at great speed.

“What are you going to do first?” asked Ned.

“Fly around a bit, and then come back over my house.  I’m going to try the lantern on that first, and see what I can make out from a couple of miles up in the air.”

Up and up went the Falcon, silently and powerfully, until the barograph registered nearly fourteen thousand feet.

“This is high enough.” spoke Tom.

He shifted a lever that brought the searchlight into focus on Shopton, which lay below them.  Then, turning on the current, a powerful beam of light gleamed out amid the blackness.