"All right then. Go ahead."
Ned talked of the weather—of anything. Meanwhile Tom was busy. Concealed in the booth occupied by Ned was a sending plate. It could not be seen unless one knew just where to look for it. In Tom's booth was a receiving plate.
The experiment did not take long. Presently Tom called to Ned that he need stay there no longer.
"Come on to the house," invited the young inventor, "and we'll develope this plate." For in this system it was necessary to develope the receiving plate, as is done with an ordinary photographic one. Tom wanted a permanent record.
Eagerly the chums in the dark room looked down into the tray containing the plate and the developing solution.
"Something's coming out!" cried Ned, eagerly.
"Yes! And it's you!" exclaimed Tom. "See, Ned, I got your picture over the telephone. Success! I've struck it! This is the best yet!"
At that moment, as the picture came out more and more plainly, someone knocked on the door of the dark room.
"Who is it?" asked Tom.
