"Oh, well, all you wanted to do was to get me out of a rut, as you called it," laughed Tom. "And you've done it--you and Mr. Peters together. It jolted up my brain, and I guess I can think better now. Come on back and watch me tinker away, Ned."

"Not much! I'm going to stay out and get some fresh air while I can. You'd better, too."

"I will, later."

So Tom turned back to his workshop, and Ned strolled on into the country, for his day's work at the bank was over. And for some time after that--until far into the night--Tom Swift worked at the knotty problem of the photo telephone.

But the young inventor was baffled. Try as he might, he could not get the image to show on the metal plate, nor could he get any results by using a regular photographic plate, and developing it afterward.

"There is something wrong with the transmission of the light waves over the wire," Tom confessed to his father.

"You'll never do it, Tom," said the aged inventor. "You are only wasting a whole lot of time."

"Well, as I haven't anything else to do now, it isn't much loss," spoke Tom, ruefully. "But I'm going to make this work, Dad!"

"All right, son. It's up to you. Only I tell you it can't be done."

Tom, himself, was almost ready to admit this, when, a week later, he seemed to be no nearer a solution of the problem than he was at first. He had tried everything he could think of, and he had Eradicate and Koku, the giant, almost distracted, by making them stay in small telephone booths for hours at a time, while the young inventor tried to get some reflection of one face or the other to come over the wire.