"There wasn't the slightest clue left after the Black Tom affair?" Mary asked, as she straightened her hat.

"Not one. We did find two of the bombs that hadn't exploded--devilishly clever arrangements, with a new combination of chemicals. Something was evidently wrong with the mixture, though, for they wouldn't go off, even when our experts started to play with them. The man who made them evidently wasn't quite sure of his ground. But there wasn't a thing about the bombs themselves that would provide any indication of where they came from."

"The man who made them must have had a pretty thorough knowledge of chemistry," Mary mused.

"Mighty near perfect," admitted Walters. "At least six exploded on time, and, from what I understand, they were loaded to the muzzle with a mixture that no one but an expert would dare handle."

"And," continued Mary, with just a hint of excitement in her voice, "the bomb-maker would continue to investigate the subject. He would want to get the latest information, the most recent books, the--"

"What are you driving at?" Walters interrupted.

"Just this," and Mary leaned across the table so that there was no possibility of being overheard. "We girls have a good deal of time on our hands, so we get into the habit of making conjectures and forming theories about the 'regulars'--the people who come into the Library often enough for us to know them by sight.

"Up to a month ago there was a man who dropped into the reference room nearly every day to consult books from Shelf Forty-five. Naturally he came up to my desk, and, as he usually arrived during the slack periods, I had plenty of time to study him. Maybe it was because I had been reading Lombroso, or possibly it's because I am just naturally observant, but I noticed that, in addition to each of his ears being practically lobeless, one of them was quite pointed at the top--almost like a fox's.

"For a week he didn't show up, and then one day another man came in and asked for a book from Shelf Forty-five. Just as he turned away I had a shock. Apparently he wasn't in the least like the other man in anything save height--but neither of his ears had any lobes to speak of and the top of them was pointed! When he returned the book I looked him over pretty thoroughly and came to the conclusion that, in spite of the fact that his general appearance differed entirely from the other man's, they were really one and the same!"

"But what," grumbled Walters, "has that to do with the Black Tom explosion?"

"The last time this man came to the Library," said Mary, "was two days before the night you failed to arrive--two days before the explosion.

And--Do you know what books are kept on Shelf Forty-five?"

"No. What?"

"The latest works on the chemistry of explosives!"

Walters sat up with a jerk that threatened to overthrow the table.

"Mary," he said, in a whisper, "I've a hunch that you've succeeded where all the rest of us fell down! The disguises and the constant reference to books on explosives are certainly worth looking into. What name did this man give?"

"Names," she corrected. "I don't recall what they were or the addresses, either. But it would be easy to find them on the cards. We don't have very many calls for books from Shelf Forty-five."

"It doesn't matter, though," and Walters slipped back into his disconsolate mood. "He wouldn't leave a lead as open as that, of course."

"No, certainly not," agreed Mary. "But the last time he was there he asked for Professor Stevens's new book. It hadn't come in then, but I told him we expected it shortly. So, unless you men have scared him off, he'll be back in a day or two--possibly in a new disguise. Why don't you see the librarian, get a place as attendant in the reference room, and I'll tip you off the instant I spot that pointed ear. That's one thing he can't hide!"

The next morning there was a new employee in the reference room. No one knew where he came from and no one--save the librarian and Mary McNilless--knew what he was there for, because his princ.i.p.al occupation appeared to be lounging around inconspicuously in the neighborhood of the information desk. There he stayed for three days, wondering whether this clue, like all the rest, would dissolve into thin air.

About five o'clock on the afternoon of the third day a man strolled up to Mary's desk and asked if Professor Stevens's book had come in yet. It was reposing at that moment on Shelf Forty-five, as Mary well knew, but she said she'd see, and left the room, carefully arranging her hair at the back of her neck with her left hand--a signal which she and d.i.c.k had agreed upon the preceding evening.

Before she returned the new attendant had vanished, but d.i.c.k Walters, in his usual garb, was loitering around the only entrance to the reference room, watching the suspect out of the corner of his eye.

"I'm sorry," Mary reported, "but the Stevens book won't be in until to-morrow," and she was barely able to keep the anxiety out of her voice as she spoke.

Had d.i.c.k gotten her signal? Would he be able to trail his man? Could he capture him without being injured? These and a score of other questions rushed through her mind as she saw the German leave the room. Once outside--well, she'd have to wait for d.i.c.k to tell her what happened then.

The man who was interested in the chemistry of explosives apparently wasn't in the least afraid of being followed, for he took a bus uptown, alighted at Eighty-third Street, and vanished into one of the innumerable small apartment houses in that section of the city. Walters kept close behind him, and he entered the lobby of the apartment house in time to hear his quarry ascending to the fourth floor. Then he signaled to the four men who had followed him up the Avenue in a government-owned machine--men who had been stationed outside the Library in the event of just such an occurrence--and instructed two of them to guard the rear of the house, while the other two remained in front.

"I'm going to make this haul myself," Walters stated, "but I want you boys to cover up in case anything happens to me. No matter what occurs, don't let him get away. Shoot first and ask questions afterward!" and he had re-entered the house almost before he finished speaking.

On the landing at the third floor he paused long enough to give the men at the rear a chance to get located. Then--a quick ring at the bell on the fourth floor and he waited for action.

Nothing happened. Another ring--and still no response.

As he pressed the b.u.t.ton for the third time the door swung slowly inward, affording only a glimpse of a dark, uninviting hall. But, once he was inside, the door closed silently and he heard a bolt slipped into place. Simultaneously a spot light, arranged over the doorway, flashed on and d.i.c.k was almost dazzled by the glare. Out of the darkness came the guttural inquiry:

"What do you want?"

"Not a thing in the world," replied Walters, "except to know if a man named Simpson lives here."

"No," came the voice, "he does not. Get out!"

"Sure I will if you'll pull back that bolt. What's the idea, anyhow?

You're as mysterious as if you were running a bomb factory or something--"

As he spoke he ducked, for if the words had the effect he hoped, the other would realize that he was cornered and attempt to escape.

A guttural German oath, followed by a rapid movement of the man's hand toward his hip pocket was the reply. In a flash d.i.c.k slipped forward, bending low to avoid the expected attack, and seized the German in a half nelson that defied movement. Backing out of the circle of light, he held the helpless man in front of him--as a shelter in case of an attack from other occupants of the apartment--and called for a.s.sistance.

The crash of gla.s.s at the rear told him that reinforcements had made their way up the fire escape and had broken in through the window. A moment later came the sound of feet on the stairs and the other two operatives were at the door, revolvers drawn and ready for action.

But there wasn't any further struggle. Von Ewald--or whatever his real name was, for that was never decided--was alone and evidently realized that the odds were overwhelming. Meekly, almost placidly, he allowed the handcuffs to be slipped over his wrists and stood by as the Secret Service men searched the apartment. Not a line or record was found to implicate anyone else--but what they did discover was a box filled with bombs precisely like those picked up on the scene of the Black Tom explosion, proof sufficient to send the German to the penitentiary for ten years--for our laws, unfortunately, do not permit of the death penalty for spies unless caught red-handed by the military authorities.

That he was the man for whom they were searching--the mysterious "No.

859"--was apparent from the fact that papers concealed in his desk contained full details as to the arrangement of the Nemours plant at Wilmington, Delaware, with a dozen red dots indicative of the best places to plant bombs. Of his a.s.sociates and the manner in which he managed his organization there wasn't the slightest trace. But the Black Tom explosion, if you recall, was the last big catastrophe of its kind in America--and the capture of von Ewald was the reason that more of the German plots didn't succeed.

The Treasury Department realized this fact when Mary McNilless, on the morning of the day she was to be married to d.i.c.k Walters, U. S. S. S., received a very handsome chest of silver, including a platter engraved, "To Miss Mary McNilless, whose cleverness and keen perception saved property valued at millions of dollars."

No one ever found out who sent it, but it's a safe bet that the order came from Washington by way of Wilmington, where the Nemours plant still stands--thanks to the quickness of Mary's Irish eyes.

V

PHYLLIS DODGE, SMUGGLER EXTRAORDINARY

Bill Quinn tossed aside his evening paper and, c.o.c.king his feet upon a convenient chair, remarked that, now that peace was finally signed, sealed, and delivered, there ought to be a big boom in the favorite pastime of the idle rich.

"Meaning what?" I inquired.

"Smuggling, of course," said Quinn, who only retired from Secret Service when an injury received in action forced him to do so.

"Did you ever travel on a liner when four out of every five people on board didn't admit that they were trying to beat the customs officials one way or another--and the only reason the other one didn't follow suit was because he knew enough to keep his mouth shut. That's how Uncle Sam's detectives pick up a lot of clues. The amateur crook never realizes that silence is golden and that oftentimes speech leads to a heavy fine.

"Now that the freedom of the seas is an accomplished fact the whole crew of would-be smugglers will doubtless get to work again, only to be nabbed in port. Inasmuch as ocean travel has gone up with the rest of the cost of living, it'll probably be a sport confined to the comparatively rich, for a couple of years anyhow.

"It was different in the old days. Every steamer that came in was loaded to the eyes and you never knew when you were going to spot a hidden necklace or a packet of diamonds that wasn't destined to pay duty. There were thrills to the game, too, believe me.