As the big car ahead slipped along eastward, we followed at such a distance as not to attract attention. It was easy enough to do that, but not so easy to avoid getting tied up among the trucks laden with foodstuffs of every description which blocked the streets over in this part of town.

Where the car ahead was bound, we did not know, but I could see that the driver was a stocky fellow, who slouched down into his seat, and handled his car almost as if it had been a mere toy. It was, I felt positive, the man whom McBirney had reported one night about the neighbourhood of Longacre Square in the car which had once been Warrington's. This, at least, was a different car, I knew. Now I realised the wisdom of allowing this man, whom they called the Boss, to go free. Under the influence of Garrick's "plant," he was to lead us to the right trail to the Chief.

It was easier now to follow the car since it had worked its way into lower Fifth Avenue. On uptown it went. We hung on doggedly in the ma.s.s of traffic going north at this congested hour.

At last it turned into Forty-seventh Street. It was stopping at the ladies' gambling joint, apparently to confirm the news. I had thought that the place was closed, until the present trouble blew over, but it seemed that there must be someone there. The Boss was evidently well known, for he was immediately admitted.

Garrick did not stop. He kept on around the corner to the raided poolroom on the next street. Dillon's man, who had been stationed there to watch the place, bowed and admitted him.

"I'm going to throw it into him good, this time," remarked Garrick, as he entered. "I've been planning this stunt for an emergency--and it's here. Now for the big scare!"

CHAPTER XX

THE SPEAKING ARC

"Looks pretty deserted here," remarked Garrick to Dillon's man, who had accompanied us from the door into the now deserted gambling den.

"Yes," he grinned, "there's not much use in keeping me here since they took all the stuff to headquarters. Now and then one of the old rounders who has been out of town and hasn't heard of the raid comes in. You should see their faces change when they catch sight of my uniform. They never stop to ask questions," he chuckled. "They just beat it."

I was wondering how the police regarded Garrick's part in the matter, and while Garrick was busy I asked, "Have you seen Inspector Herman lately?"

The man laughed.

"What's the matter?" I asked, "Is he sore at having the raid pulled off over his head?"

"Sore?" the roundsman repeated, "Oh, not a bit, not a bit. He enjoyed it. It gave him so much credit," the man added sarcastically, "especially after he fell down in getting the evidence against that other place around the corner."

"Was that his case, too?" I asked.

"Sure," replied the policeman. "Didn't you know that? That Rena Taylor was working under his orders when she was killed. They tell me at headquarters he's working overtime on the case and other things connected with it. He hasn't said much, but there's someone he is after--I know. Mark my words. Herman is always most dangerous when he's quiet. The other day he was in here, said there was a man who used to be seen here a good deal in the palmy days, who had disappeared. I don't know who he was, but Herman asked me to keep a particular lookout to see if he came back for any purpose. There's someone he suspects, all right."

I wondered why the man told me. He must have seen, by the look on my face, that I was thinking that.

"I wouldn't tell it to everybody," he added confidentially, "only, most of us don't like Herman any too well. He's always trying to hog it all--gets all the credit if we pick up a clew, and,--well, most of us wouldn't be exactly disappointed to see Mr. Garrick succeed--that's all."

Garrick was calling from the back room to me, and I excused myself, while the man went back to his post at the front door. Garrick carefully closed the door into the room.

While I had been busy getting the copies of the faked edition of the Star, which had so alarmed the owner of the garage and had set things moving rapidly, Garrick had also been busy, in another direction. He had explored not only the raided gambling den, but the little back yard which ran all the way to an extension on the rear of the house in the next street, in which was situated the woman's poolroom.

He had explored, also, the caved-in tunnel enough to make absolutely certain that his suspicions had been correct in the first place, and that it ran to this other joint, from which the gamblers had made their escape. That had satisfied him, however, and he had not unearthed the remains of the tunnel or taken any action in the matter yet. Something else appeared to interest him much more at the present moment.

"I found," he said when he was sure that we were alone, "that the feed wire of the arc light that burns all the time in that main room over there in the place on Forty-seventh Street--you recall it?--runs in through the back of the house."

He was examining two wires which, from his manner, I inferred were attached to this feed wire, leading to it from the room in which we now were. What the purpose of the connection was I had no idea. Perhaps, I thought, it was designed to get new evidence against the place, though I could not guess how it was to be done. So far, except for what we had seen on our one visit, there had appeared to be no real evidence against the place, except, possibly, that which had died with the unfortunate Rena Taylor.

"What's that?" I asked, as Garrick produced a package from a closet where he had left it, earlier in the day.

I saw, after he had unwrapped it, that it was a very powerful microphone and a couple of storage cells. He attached it to the wire leading out to the electric light feed wire.

"I had provided it to be used in an emergency," he replied. "I think the time has come sooner than I antic.i.p.ated."

I watched him curiously, wondering what it would be that would come next.

There followed a most amazing series of groanings and mutterings from Garrick. I could not imagine what he was up to. The whole proceeding seemed so insane that, for the moment, it left me nonplussed and speechless.

Garrick caught the puzzled look on my face.

"What's the matter?" he laughed heartily, cutting out the microphone momentarily and seeming to enjoy the joke to the utmost.

"Would you prefer to be sent to a State or a private inst.i.tution?" I rasped, testily. "What insanity is all this? It sounds like the fee-faw-fum and mummery of a voodoo man."

"Come, now, Tom," he rejoined, argumentatively. "You know as well as I do what sort of people those gamblers are--superst.i.tious as the deuce.

I did this once before to-day. This is a good time to do it again, before they persuade themselves that there is nothing in that story which we printed in the Star. That fellow is in there now, probably in that room where we were, and it is possible that they may rea.s.sure him and settle his fears. Now, just suppose a murder had been committed in a room, and you knew it, and heard groanings and mutterings--from nowhere, just in the air, about you, overhead--what would you do, if you were inclined to be superst.i.tious?"

Before I could answer, he had resumed the antics which before I had found so inexplicable.

"Cut out and run, I suppose," I replied. "But what has that to do with the case? The groanings are here--not there. You haven't been able to get in over there to attach anything, have you? What do you mean?"

"No," he admitted, "but did you ever hear what you could do with a microphone, a rheostat, and a small transformer coil if you attached them properly to a direct-current electric lighting circuit? No? Well, an amateur with a little knowledge of electricity could do it. The thing is easily constructed, and the result is a most complicated matter."

"Well?" I queried, endeavouring to follow him.

"The electric arc," he continued, "isn't always just a silent electric light. You know that. You've heard them make noises. Under the right conditions such a light can be made to talk--the 'speaking arc,' as Professor Duddell calls it. In other words, an arc light can be made to act as a telephone receiver."

I could hardly believe the thing possible, but Garrick went on explaining.

"You might call it the arcophone, I suppose. The scientific fact of the matter is that the arc is sensitive to very small variations of the current. These variations may run over a wide range of frequency. That suggested to Duddell that a direct-current arc might be used as a telephone receiver. All that you need is to add a microphone current to the main arc current. The arc reproduces sounds and speech distinctly, loud enough, even, to be heard several feet away from the light."

He had cut out the microphone again while he was talking to me. He switched it in again with the words, "Now, get ready, Tom. Just one more; then we must hurry around in that car of ours and watch the fun."

This time he was talking into the microphone. In a most solemn, sepulchral voice he repeated, "Let the slayer of Rena Taylor beware.

She will be avenged! Beware! It will be a life for a life!"

Three times he repeated it, to make sure that it would carry. Then, grabbing up his hat and coat, he dashed out of the room, past the surprised policeman at the door, and took the steps in front of the house almost at a bound.

We hardly had time to enter our own car and reach the corner of Forty-seventh Street, when the big black automobile which we had followed uptown shot by almost before the traffic man at the crossing could signal a clear road.

"We must hang onto him!" cried Garrick, turning to follow. "Did you catch a glimpse of his face? It's our man, the go-between, the keeper of the garage whom they call the Boss. He was as pale as if he had seen a ghost. I guess he did think he heard one. Between the news-paper fake and the speaking arc, I think we've got him going. There he is."

It was an exciting ride, for the man ahead was almost reckless, though he seemed to know instinctively still just when to put on bursts of speed and when to slow down to escape being arrested for speeding. We hung on, managing to keep something less than a couple of blocks behind him. It was evident that he was making for the ferry uptown across the river to New Jersey, and, taking advantage of this knowledge, Garrick was able to drop back a little, and approach the ferry by going down a different street so that there was no hint yet that we were following him.

By judicious jockeying we succeeded in getting on the boat on the opposite side from the car we were following, and in such a way that we could get off as soon as he could. We managed to cross the ferry, and, in the general scramble that attends the landing, to negotiate the hill on the other side of the river without attracting the attention of the man in the other car. His one idea seemed to be speed, and he had no suspicion, apparently, that in his flight he was being followed.

As we bowled along, forced by circ.u.mstances to take the fellow's dust, Garrick would quietly chuckle now and then to himself.