"I'll remember that, when we have ours completed," promised his chum, "and I'll take you for a spin."
The boys talked for perhaps an hour longer, mostly about the airship, for it was the latest mechanical affair in which Tom was interested, and, naturally, foremost in his thoughts. Then Ned went home first, however, telephoning from Tom's house to the bank president about having seen the suspicious men. That official thanked his young employee, and said he would take all necessary precautions. The telephone message was not sent until Mr. Swift was out of hearing, as Tom was determined that his father should have no unnecessary worry about the unscrupulous men. As it was, the news that the gang was out of jail had caused the aged inventor some alarm.
It was not without some anxiety that Tom arose the next morning, fearing he would hear news that the bank had been broken into, but no such alarming report circulated in Shopton. In fact having made some inquiries that day of Ned, he learned that no trace had been seen of the mysterious men. The police had been on the lookout, but they had seen nothing of them.
"Maybe, after all, they weren't the same ones," suggested Ned, when he paid Tom another visit the next night.
"Well, of course it's possible that they weren't," admitted the young inventor. "I'd be very glad to think so. Even if they were, your encounter with them may have scared them off; and that would be a good thing."
The next two weeks were busy ones for Tom and Mr. Sharp. Aided occasionally by Mr. Swift, and with Garret Jackson, the engineer, to lend a hand whenever needed, the aeronaut and the owner of the speedy Arrow made considerable progress on their airship.
"What is your father so busy over?" asked Mr. Sharp one day, when the new aluminum gas holder was about completed.
"I don't know," answered Tom, with a somewhat puzzled air. "He doesn't seem to want to talk about it, even to me. He says it will revolutionize travel along a certain line, but whether he is working on an airship that will rival ours, or a new automobile, I can't make out. He'll tell us in good time. But when do you think we will finish the—well, I don't know what to call it—I mean our aeroplane?"
"Oh, in about a month now. That's so, though, we haven't a name for it. But we'll christen it after it's completed. Now if you'll tighten up some of those bolts I'll get the gas generating apparatus in readiness for another test."
A short description of the new airship may not be out of place now. It was built after plans Mr. Sharp had shown to Tom and his father soon after the thrilling rescue of the aeronaut from the blazing balloon over Lake Carlopa. The general idea of the airship was that of the familiar aeroplane, but in addition to the sustaining surfaces of the planes, there was an aluminum, cigar-shaped tank, holding a new and very powerful gas, which would serve to keep the ship afloat even when not in motion.