Once more Ned glanced at the pressure gage.  It showed seven hundred pounds now, and there was only a margin of safety of one hundred pounds more, ere a terrific explosion would occur.  Still Tom had not given the order to descend to earth.

“Are you going to make it, Tom?” asked the government agent, anxiously, as he stood over the young inventor.

“I—­I think so,” panted Tom.  “Are we near the Dominion line,”

“Pretty close,” was the discouraging answer.  “I’m afraid we can’t get ’em before they cross.  Can you use any more speed?”

“I don’t know.  Ned, see if you can get another notch out of her.”

With one hand Ned reached for the accelerator lever on the wall near him, and pulled it to the last notch.  The Falcon shot ahead with increased speed, but, at the same instant there came a gasp from Koku, and the sound of something breaking.

“There!  He’s done it!” cried Tom in despair.  “I was afraid you’d be too strong for that wrench, Koku.  You’ve broken off the handle.  Now we’ll never be able to loosen that valve.”

Ned gave one more glance at the pressure gage.  It showed seven hundred and fifty pounds, and the needle was slowly moving onward.

“Hadn’t we better descend,” asked Mr. Whitford in a low voice.

“I—­I guess so,” answered Tom, despairingly.  “Where are we?”

Ned flashed the light downward for an instant.

“Just crossing over the St. Regis Indian reservation again,” he replied.  “We’ll be in Canada in a few minutes more.”

“Where are the smugglers?”

“Still ahead, and they’re bearing off to the right.”

“Going toward Montford,” commented the government man.  “We’ve lost ’em for to-night, anyhow, but they didn’t get their goods landed, at any rate.”

“Send her down, Ned!” exclaimed Tom, and it was high time, for the pressure was now within twenty-five pounds of the exploding point.

Down shot the Falcon, while her rival passed onward triumphantly in the darkness.  Ned held the light on the smugglers as long as he dared, and then he flashed it to earth to enable Mr. Damon to pick out a good landing place.

In a few moments Tom’s silent airship came to rest on a little clearing in the forest, and Tom, with Ned’s help, at once opened every outlet of the gas machine, a thing they had not dared do while up in the air.

“Come on, now, run, everybody!” cried Tom.  “Otherwise you’ll he smothered!”

They leaped from the craft, about which gathered the fumes of the powerful gas, as it hissed from the pipes.  Running a hundred yards away they were safe, and could return in a few minutes.

“We’re in Canada,” remarked Mr. Whitford, as they came to a halt, watching the airship.

“How do you know?” asked Ned.

“As we landed I saw one of the stone boundary posts,” was the answer.  “We’re on English territory, and we can’t touch the smugglers if we should see them now.”