"Let's go round to the back of the shed. We can soon find out if anyone was really there, or if your imagination played you a trick."
Herc readily agreed. He was fairly boiling with anger. But, on investigation, the fresh paint at the rear of the shed proved not to be scratched, as must have been the case had any one clambered up to the window.
"Looks to me as if you're seeing things," teased Ned.
"Does look rather like it," confessed Herc. "It seems as if--hullo, what--what's that? I guess that's how he reached the window without scratching the paint."
He pointed to a short ladder, evidently left behind by the workmen who had fitted up the hangars. It lay in some tall grass, a short distance from where the Dreadnought Boys stood. A hasty attempt seemed to have been made to hide it, but if this had been the case, it was unsuccessful.
"Just as I thought," declared Herc, after a minute. "The grass here is freshly trampled by the chap who threw the ladder back."
"I wonder how much they overheard?" he said slowly.
"All our conversation, I guess, if they arrived in time. Why?"
"Because I wanted to keep my pontoon idea secret till I'd tried it out. It isn't exactly for general publication--yet."
Herc seemed to catch a deeper meaning in the words.
"You're thinking of that chap who's been snooping around here for the last week posing as a newspaper photographer?" he asked quickly.
"Yes. I'm convinced, somehow, that he is nothing of the sort. For one thing, he's far too curious about the mechanical details of the aeroplanes, and the results of the experiments so far as we've conducted them. Another thing is, that he seems unusually well supplied with money, and he also appears to be a man of far greater ability than his supposed job would indicate."
"Gee whillakers!" gasped Herc. "You're not after thinking he's a foreign spy?"
"That's just what I am," rejoined Ned firmly.
"Not if he depended on most of us for it. But there's Chance and Merritt. It's a mean thing to say, Herc, but I wouldn't trust those fellows any farther than I could see them, and not so far as that."
"We-el!" whistled Herc, with huge assumed surprise, "you don't say so? I was always under the delusion that they were honest, above-board sports, who wouldn't do a mean thing for all the wealth on Wall Street."