Chapter XXI. The Photo Telephone
 

Tom Swift was taking, as he afterward confessed, "a mighty big chance." But it seemed the only way. He was working against cunning men, and had to be as cunning as they.

True, the man he hoped to capture, through the combination of his photo telephone and the phonograph, might go to some other instrument than one of those Tom had adjusted. But this could not be helped. In all he had put his new attachment on eight 'phones in the vicinity of the sawmill. So he had eight chances in his favor, and as many against him as there were other telephones in use.

"It's a mighty small margin in our favor," sighed Tom.

"It sure is," agreed Ned. They were at Mrs., Damon's house, waiting for the call to come in.

"But we couldn't do anything else," went on Tom.

"No," spoke Ned, "and I have a great deal of hope in the proverbial Swift luck, Tom."

"Well, I only hope it holds good this time!" laughed the young inventor.

"There are a good many things that can go wrong," observed Ned. "The least little slip-up may spoil your traps, Tom."

"I know it, Ned. But I've got to take the chance. We've just got to do something for Mrs. Damon. She's wearing herself out by worrying," he added in a low voice, for indeed the wife of his friend felt the absence of her husband greatly. She had lost flesh, she ate scarcely anything, and her nights were wakeful ones of terror.

"What if this fails?" asked Ned.

"Then I'm going to work that button clue to the limit," replied Tom. "I'll go to Boylan and see what he and Peters have to say."

"If you'd done as I suggested you'd have gone to them first," spoke Ned. "You'll find they're mixed up in this."

"Maybe; but I doubt it. I tell you there isn't a clue leading to Peters--as yet."

"But there will be," insisted Ned. "You'll see that that I'm right this time."

"I can't see it, Ned. As a matter of fact, I would have gone to Boylan about that button I found in my airship only I've been so busy on this photo telephone, and in arranging the trap, that I haven't had time. But if this fails--and I'm hoping it won't--I'll get after him," and there was a grim look on the young inventor's face.

It was wearying and nervous work--this waiting. Tom and Ned felt the strain as they sat there in Mrs. Damon's library, near the telephone. It had been fitted up in readiness. Attached to the receiving wires was a sensitive plate, on which Tom hoped would be imprinted the image of the man at the other end of the wire--the criminal who, in exchange for the valuable land papers, would give Mr. Damon his liberty.

There was also the phonograph cylinder to record the man's voice. Several times, while waiting for the call to come in, Tom got up to test the apparatus. It was in perfect working order.

As before, there was an extension telephone, so that Mrs. Damon could talk to the unknown, while Tom could hear as well. But he planned to take no part in the conversation unless something unforeseen occurred.

Mr. Damon was an enthusiastic photographer, and he had a dark room adjoining his library. 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 be 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 make a prisoner of the man whose features would be revealed to him over the wire.

It was a hazardous plan--a risky one--but it was the best that he could evolve. Tom had instructed Mrs. Damon to keep the man in conversation as long as possible, in order to give the young inventor himself time to rush off in his airship. But of course the man might get suspicious and leave. That was another chance that had to be taken.

"If I had thought of it in time," said Tom, musingly, as he paced up and down in the library waiting for the 'phone to ring, "if I had thought of it in time I would have rigged up two plates--one for a temporary, or looking-glass, picture, and the other for a permanent one. In that way I could rush off as soon as I got a glimpse of the fellow. But it's too late to do that now. I'll have to develop this plate."

Waiting is the most wearisome work there is. Tom and Ned found this to be the case, as they sat there, hoping each moment that the telephone bell would ring, and that the man at the other end of the wire would be the mysterious stranger. Mrs. Damon, too, felt the nervous strain.

"This is about the hour he called up yesterday," said Tom, in a low voice, after coming back from a trip to the window to see that his airship was in readiness. He had brought over to help in starting it, for he was using his most powerful and speedy craft, and the propellers were hard to turn.

"Yes," answered Mrs. Damon. "It was just about this hour, Tom. Oh, I do hope--"

She was interrupted by the jingle of the telephone bell. With a jump Tom was at the auxiliary instrument, while Mrs. Damon lifted off the receiver of her own telephone.

"Yes; what is it?" she asked, in a voice that she tried to make calm.

"Do you know who this is?" Tom heard come over the wire.

"Are you the--er--the person who was to give me an address where I am to send certain papers?"

"Yes. I'm the same one. I'm glad to see that you have acted sensibly. If I get the papers all right, you'll soon have your husband back. Now do as I say. Take down this address."

"Very well," assented Mrs. Damon. She looked over at Tom. He was intently listening, and he, too, would note the address given. The trap was about to be sprung. The game had walked into it. Just which telephone was being used Tom could not as yet tell. It was evidently not the one nearest the planing mill, for Tom could not hear the buzzing sound. It was well he had put his attachment on several instruments.

"One moment, please," said Mrs. Damon, to the unknown at the other end of the wire. This was in accordance with the pre-arranged plan.

"Well, what is it?" asked the man, impatiently. "I have no time to waste."

Tom heard again the same gruff tones, and he tried in vain to recognize them.

"I want you take down a message to Mr. Damon," said his wife. "This is very important. It can do you no harm to give him this message; but I want you to get it exact. If you do not promise to deliver it I shall call all negotiations off."

"Oh, all right I'll take the message; but be quick about it. Then I'll give you the address where you are to send the papers."

"This is the message," went on Mrs. Damon. "Please write it down. It is very important to me. Have you a pencil?"

"Yes, I have one. Wait until I get a bit of paper. It's so dark in this booth--wait until I turn on the light."

Tom could not repress a pleased and joyful exclamation. It was just what he had hoped the man would do--turn on the light in the booth. Indeed, it was necessary for the success of the trap that the light be switched on. Otherwise no picture could be transmitted over the wire. And the plan of having the man write down a message to Mr. Damon was arranged with that end in view. The man would need a light to see to write, and Tom's apparatus must be lighted in order to make it work. The plot was coming along finely.

"There!" exclaimed the man at the other end of the wire. "I have a light now. Go ahead with your message, Mrs. Damon. But make it short. I can't stay here long."

Then Mrs. Damon began dictating the message she and Tom had agreed upon. It was as long as they dared make it, for they wanted to keep the man in the booth to the last second.

"Dear Husband," began Mrs. Damon. What the message was does not matter. It has nothing to do with this story. Sufficient to say that the moment the man began writing it down, as Tom could tell over the sensitive wire, by the scratching of the pencil--at that moment Tom, knowing the light was on in the distant telephone booth, switched on the picture-taking apparatus. His receiving apparatus at once indicated that the image was being made on the sensitive plate.

It took only a few seconds of time, and with the plate in the holder Tom hastened to the dark room to develop it. Ned took his chum's place at the telephone, to see that all worked smoothly. The photo telephone had done it's work. Whose image would be found imprinted on the sensitive plate? Tom's hands trembled so that he could scarcely put it in the developing solution.