Further search the next morning brought forth no clues, though Tom, Ned and the others beat about in the bushes where the men had disappeared.
One or two reports were heard from surrounding towns, to the effect that several persons had heard a strange throbbing sound in the night, that, possibly, was caused by the passage of the airship overhead. One such report came from Waterford, the home town of Mr. Damon.
"Let's go over there," suggested Ned, to his chum. "I'd like to see our friend, and maybe can get some other clues by circulating around there."
"Oh, I don't know," spoke Tom, rather listlessly.
"Why not?" Ned wanted to know.
"Well, I ought to be working on my photo telephone," was the answer. "I've got a new idea now. I'm going to try a different kind of current, and use a more sensitive plate. And I'll use a tungsten filament lamp in the sending booth."
"Oh, let your experiments go for a little while, Tom," suggested Ned. "Come on over to Mr. Damon's. The trouble with you is that you keep too long at a thing, once you start."
"That's the only way to succeed," remarked
