CHAPTER XV
THE AIRSHIP CLUE
"Now Ned, we'll try again. I'm going to use a still stronger current, and this is the most sensitive selenium plate I've turned out yet. We'll see if we can't get a better likeness of you—one that will be plainer."
It was Tom Swift who was speaking, and he and his chum had just completed some hard work on the new photo telephone. Though the apparatus did what Tom had claimed for it, still he was far from satisfied. He could transmit over the wire the picture of a person talking at the telephone, but the likeness was too faint to make the apparatus commercially profitable.
"It's like the first moving pictures," said Tom. "They moved, but that was about all they did."
"I say," remarked Ned, as he was about to take his place in the booth where the telephone and apparatus were located, "this double-
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