"Yes. That fellow Garrick is just as likely as not to be nosing around up there. I'd go but for that."

"I know. But suppose we find that he isn't there, that he isn't in the house--has been there and left it. That would be safe enough. You're right. Nothing doing if he's there. We must can him in some way. But, say,--I know how to get in all right without being seen. I'll tell you later. Come on, be a sport. We won't try it if anybody's there.

Besides, if we succeed it will help to throw a scare into Warrington."

The man on our end of the telephone appeared to hesitate.

"I'll tell you what I'll do, Chief," he said at length. "I'll meet you at the same place as we met the other day--you know where I mean--some time after twelve. We'll talk it over. You're sure about the letter?"

"As sure as if I'd seen it."

"All right. Now, be there. I won't promise about this Warrington business. We'll talk that over. But I have other things I want to tell you--about this situation here at the garage. I want to know how to act."

"All right. I'll be there. Good-bye."

"So long, Chief."

The conversation stopped. I looked anxiously at Garrick to see how he had taken it.

"And so," he remarked simply, as after a moment's waiting we made sure that the machine had stopped talking, "it appears that our friends, the enemy, are watching us as closely as we are watching them--with the advantage that they know us and we don't know them, except this garage fellow."

Garrick lapsed into silence. I was rapidly turning over in my mind what we had just overheard and trying to plan some way of checkmating their next move.

"Here's a plot hatching to rob Warrington's safe," I exclaimed helplessly.

"Yes," repeated Garrick slowly, "and if we are going to do anything about it, it must be done immediately, before we arouse suspicion and scare them off. Did you hear those footsteps over the detectaphone?

That was the Boss going out of the garage. So, they expect me around there, nosing about Warrington's apartment. Well, if I do go there, and then ostentatiously go away again, that will lure them on."

He reached his decision quickly. Grabbing his hat, he led the way out of the Old Tavern and up the street until we came to a drug store with a telephone.

I heard him first talking with Warrington, getting from him the combination of the safe, over long distance. Then he called up his office and asked the boy to meet him at the Grand Central subway station with a package, the location of which he described minutely.

"We'll beat them to it," he remarked joyously, as we started leisurely uptown to meet the boy.

Chapter XIII

THE INCENDIARY

"The Warrington estate owns another large apartment house, besides the one where Warrington has his quarters, on the next street," remarked Garrick, half an hour later, after we had met the boy from his office.

"I have arranged that we can get in there and use one of the empty suites."

Garrick had secured two rather good-sized boxes from the boy, and was carrying them rather carefully, as if they contained some very delicate mechanism.

Warrington, we found, occupied a suite in a large apartment on Seventy-second Street, and, as we entered, Garrick stopped and whispered a few words to the hall-boy.

The boy seemed to be more than usually intelligent and had evidently been told over the telephone by Warrington that we were coming. At least we had no trouble, so far.

Warrington's suite was very tastefully furnished for bachelor quarters.

In the apartment, Garrick unwrapped one of the packages, and laid it open on the table, while he busied himself opening the safe, using the combination that Warrington had given him.

I waited nervously, for we could not be sure that no one had got ahead of us, already. There was no need for anxiety, however.

"Here's the letter, just as Warrington left it," reported Garrick in a few minutes, with some satisfaction, as he banged the safe door shut and restored things so that it would not look as though the little strong box had been touched.

Meanwhile, I had been looking curiously at the box on the table. It did not seem to be like anything we had ever used before. One end was open, and the lid lifted up on a pair of hinges. I lifted it and looked in.

About half way down the box from the open end was a part.i.tion which looked almost as if some one had taken the end of the box and had just shoved it in, until it reached the middle.

The open half was empty, but in the other half I saw a sort of plate of some substance covering the outside of the shoved-in end. There was also a dry cell and several arrangements for adjustments which I did not understand. Back of the whole thing was a piece of mechanism, a clockwork interrupter, as I learned later. Wires led out from the closed end of the box.

Garrick shoved the precious letter into his pocket and then placed the box in a corner, where it was hidden by a pile of books, with the open end facing the room in the direction of the antiquated safe. The wires from the box were quickly disposed of and dropped out of the window to the yard, several stories below, where we could pick them up later as we had done with the detectaphone.

"What's that?" I asked curiously, when at last he had finished and I felt at liberty to question him.

"Well, you see," he explained, "there is no way of knowing yet just how the apartment will be entered. They apparently have some way, though, which they wouldn't discuss over the telephone. But it is certain that as long as they know that there is anyone up here, they will put off the attempt. They said that."

He was busily engaged restoring everything in the room as far as possible to its former position.

"My scheme," he went on, "is for us now to leave the apartment ostentatiously. I think that is calculated to insure the burglary, for they must have someone watching by this time. Then we can get back to that empty apartment in the house on the next street, and before they can get around to start anything, we shall be prepared for them."

Garrick stopped to speak to the hall-boy again as we left, carrying the other box. What he said I did not hear but the boy nodded intelligently.

After a turn down the street, a ride in a surface car for a few blocks and back again, he was satisfied that no one was following us and we made our way into the vacant apartment on Seventy-third Street, without being observed.

Picking up the wires from the back yard of Warrington's and running them across the back fence where he attached them to other wires dropped down from the vacant apartment was accomplished easily, but it all took time, and time was precious, just now.

In the darkness of the vacant room he uncovered and adjusted the other box, connected one set of wires to those we had led in and another set to an apparatus which looked precisely like the receiver of a wireless telegraph, fitting over the head with an earpiece. He placed the earpiece in position and began regulating the mechanism of the queer looking box.

"I didn't want to use the detectaphone again," he explained as he worked, "because we haven't any a.s.surance that they'll talk, or, if they do, that it will be worth while to listen. Besides, there may be only one of them."

"Then what is this?" I asked.

"Well," he argued, "they certainly can't work without light of some kind, can they?"

I acquiesced.

"This is an instrument which literally makes light audible," he pursued.

"Hear light?" I repeated, in amazement.

"Exactly," he reiterated. "You've said it. It was invented to a.s.sist the blind, but I think I'll be able to show that it can be used to a.s.sist justice--which is blind sometimes, they say. It is the optophone."

He paused to adjust the thing more accurately and I looked at it with an added respect.

"It was invented," he resumed, "by Professor Fournier d'Albe, a lecturer on physics at the University of Birmingham, England, and has been shown before many learned societies over there."

"You mean it enables the blind to see by hearing?" I asked.