"Any good powder left?" asked Ned.
"Not a pound. Did you hear anything?"
"Yes, one man has disappeared. Oh, Tom, we've got to fail after all! We can't save the town!"
"Yes, we can, Ned. If that dam will only hold for half an hour more."
"What do you mean?"
"I mean that I have another supply of good powder in the village. I secreted some there, you remember I told you. If I can go get that, and get back here in time, I can break down the barrier with one shot, and save Preston."
"But you never can make the trip there and back in time, with the powder, Tom. It's impossible. The dam may hold half an hour, or it may not. But, if it does, you can't do anything!"
"I can't? Well, I'm going to make a big try, Ned. You stay on the job here. Have everything ready so that when I get back with the new explosive, which I hope hasn't been tampered with, I can shove it into the breech, and set it off. Have the wires, primers and button all ready for me."
Then Tom set off on the run.
"Where are you going?" gasped his chum. "You can never run to Preston and back in time."
"I don't intend to. I'm going in my airship.
