Again did Frank make a dive into his pocket, and dangled something before the astonished eyes of his cousin.

“Great Caesar! what d’ye call those things?” gasped Andy, staring as though hardly able to believe his eyes.

“Well, as near as I can make out, they’re a couple of half masks made out of black muslin, and just like a domino worn at a masquerade ball.”  Frank remarked, with positive conviction in his voice and manner.

“Masks?” echoed the other; “and the fellows who broke open our shop wore them, did they?  Well, the crowd that came out here seemed to be satisfied to tie handkerchiefs across their faces, and pull their hats down.”

“I don’t know that they wore them,” Frank went on, “but they had the things along and laid them down with the lantern, forgetting the whole lot when they cleared out.  Perhaps your dog got to barking and frightened them off before they found a chance to do much damage.”

“A regular bullseye electric torch, and black masks like cracksmen use—­say, tell me, Frank, what’s coming over our quiet country up here lately?  There was the affair over in a neighboring town, when yeggmen broke into the bank, and robbed it; and now here you tell me we’ve had a little smash-up on our own account, with the burglars leaving cards behind them.  But what d’ye think now anybody would want to go poking around in our shop for, Frank?”

His cousin was looking very grave.

“Well, you forget that we’ve been working overtime this winter on several little inventions that, if we ever complete them, will make a stir in the world of aviation.”

“Jupiter, I had let that slip away from me, for a fact, Frank!” exclaimed the other, looking rather startled.

“Of course, it sounds pretty big for us to even imagine that any party could take enough interest in what the Bird boys are doing to come up here, intending to break into the shop, and learn our secrets; but what else can we think, tell me that, Andy?”

“But they wouldn’t find out much, even if they had six hours to poke around our shop in, would they, Frank?”

“I guess you’re right, because we’ve made it a rule to be cautious enough to hide our work and cover our tracks as we go along.  But let’s get busy now, and put the plane into shape, so we can slip along home.  And as we work we can keep on talking as much as we want to,” Frank went on to say.

The farmer and Felix still loitered around, determined to see the wonderful contrivance make a start, and expecting the greatest treat of their lives, when that event occurred.

Such experienced workers as the two Bird boys had now become would find little or no trouble about carrying out the work they had on hand.  Every steel wire guy was kept as taut as a fiddle string; and by the time they were done handling the aeroplane it would be in apple-pie shape for work.

“Did they smash much in the shop, Frank?” Andy asked after they had been working some little time, and making fair progress.