"I didn't mention that matter, but it was just as you say, Frank; both men had on masks all the time," answered the police officer.
"Black ones too, I expect?" ventured Andy.
"That's what they were; but see here, are you two just guessing this, or do you happen to know something about those men?" asked the other, quickly; for he could not help seeing from the manner of the Bird boys that they were on some sort of a scent; and he knew from past experiences that their sagacity could always be trusted to do the right thing.
"Well," Frank went on to say, drily, "while Andy was watching our new hydroplane out in the Quackenboss pasture, I worked until eleven o'clock in our shop, and then went home. This morning, early, after a bite to eat, I hurried over there to do some finishing touches and carry the thing out to apply to our broken plane, when to my astonishment I found that the shop had been broken into later in the night, as well as our hangar, where the aeroplane is usually kept. And here's what I discovered lying on the work-bench, where the men had forgotten them."
With these words he held up the flashlight torch, and the twin black masks; and they produced an immediate shock upon the Chief of Police.
"And you found those things in your workshop this morning, you say?" he cried, reaching out to take hold of the torch, and the bits of black muslin.
"Yes, and whoever was there, they must have been mad because they didn't find the aeroplane, for they smashed a few things, just for spite, it looked like," was what Frank added.
"Then, if it was the same men who robbed the bank they must have known about you boys having a brand new machine. And say, that must mean one of the robbers was something of a birdman himself; because no greenhorn would ever think of making his getaway in an aeroplane. Don't you see that's a pretty good clue, Frank? I'll remember that when I'm getting in touch with other points, and find out if there's any aviator who's gone crooked of late. Yes, that's worth knowing, now; and I'm glad you mentioned it to me."
"What description did Cadger give of the men, Chief?" queried Frank.
"Oh! he said one was tall and thin; and the other short and wiry like, pretty much like a cat. I rather reckon he'd be the fellow who's been in the flying business. Seemed to have a stiff left arm too, like he'd met up with some sort of an accident. That might turn out to be a pointer; I'll just remember it. It surely was a lucky thing for me I saw you boys come sailing along and managed to attract your attention. I begin to feel better already. You gave me so much help on that other occasion, it just seems as if I had to fall back on you again."