It was in this dark room that Tom planned to develop the photo telephone plate.
On this occasion he was not going to use the metal plate in which, ordinarily, the image of the person talking appeared. That record was but a fleeting one, as in a mirror. This time Tom wanted a permanent picture that could, if necessary, be used in a court of justice.
Tom's plan was this: If the person who had demanded the papers came to one of the photo telephones, and spoke to Mrs. Damon, Tom would switch on the receiving apparatus. Thus, while the man was talking, his picture would be taken, though he would not know of the thing being done.
His voice would also be recorded on the wax cylinder, and he would be equally unaware of this.
When Tom had imprinted the fellow's image on the prepared plate, he would go quickly to the dark room and develop it. A wet print could be made, and with this as evidence, and to use in identification, a quick trip could he made to the place whence the man had telephoned. Tom hoped thus to capture him.
To this end he had his airship in waiting, and as soon as he had developed the picture he planned to rush off to the vicinity of the sawmill, and
