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."