It did not take them long to reach the desired spot, and they hovered in the air over it, every one with tense nerves, waiting for what would happen next.

Tom did not want to show his searchlight just yet, as he feared the gleam of it might stop the operations of the smugglers.  So he waited in dark-ness, approaching close to the earth in his noiseless ship several times, and endeavoring to see something through the powerful night glasses.

Suddenly, from below them, came a subdued throb and hum of a motor.

“There they are!” exclaimed Mr. Damon.

“I think so,” agreed Tom.  He looked below.  He saw two flickering lights, rather far apart.  Mr. Whitford observed them at the same moment.

“There are two of them!” exclaimed the agent, “Two airships, Tom!”

“So I see.  Koku, get out my electric rifle.  We can’t chase two, if they separate, so I may have to stop one.  It’s best to be prepared.  I’m going to follow them in the dark, until they get over the border, and then I’ll turn on the light and the camera.  Then it will be a race to the finish.”

The twin lights came nearer.  Tom stood with his mouth to the signal tube that communicated with Mr. Damon in the pilot house.  From a side window he watched the smugglers’ airships.  They shot upward and then came on straight ahead, to pass to one side of him.  Now they were past.  Tom started the wizard camera.

“Half speed ahead!” the young inventor signalled, and the Falcon shot forward.  The night race was on.

CHAPTER XXV

THE CAPTURE—­CONCLUSION

“Do you think they know we are here, Tom?” asked Mr. Whitford, as he stood at the side of the young inventor in the motor room.

“I don’t believe so, as yet.  They can’t hear us, and, unless they have pretty powerful glasses, they can’t pick us up.  We can soon tell however, if they are aware that we are following them.”

“Have you made any plan about capturing them?”

“No, I’m going to wait and see what turns up.  I can’t certainly chase two of them, if they separate, and that’s why I’m going to cripple one if I have to.”

“But won’t that be dangerous?  I don’t want to see any of them killed, or even hurt, though they are smugglers.”

“And I don’t want to hurt them, either.  If worst comes to worst I’m going to put a few holes in the wing planes of the smaller craft.  That will cause her to lose headway, and she can’t keep up.  They’ll have to volplane to earth, but, if they know anything at all about airships, they can do that easily, and not get a bit hurt.  That will put them out of the race, and I can keep on after the big ship.  I fancy that carries the more valuable cargo.”

“I presume so.  Well, don’t bring the one to earth until you get over Uncle Sam’s territory, and then maybe there will be a chance to capture them, and the goods too.”