If you grind castor sugar with an equal quantity of chlorate of potash, the result is an innocent-looking white compound, sweet to the taste, and sometimes beneficial in the case of a sore throat. But if you dip a glass rod into a small quantity of sulphuric acid, and merely touch the harmless-appearing mixture with the wet end of the rod, the dish which contains it becomes instantly a roaring furnace of fire, vomiting forth a fountain of burning balls, and filling the room with a dense, black, suffocating cloud of smoke.

So strange a combination is that mystery which we term Human Nature, that a touch of adverse circumstance may transform a quiet, peaceable, law-abiding citizen into a malefactor whose heart is filled with a desire for vengeance, stopping at nothing to accomplish it.

In a little narrow street off the broad Rue de Rennes, near the great terminus of Mont-Parnasse, stood the clock-making shop of the brothers Delore. The window was filled with cheap clocks, and depending from a steel spring attached to the top of the door was a bell, which rang when any one entered, for the brothers were working clockmakers, continually busy in the room at the back of the shop, and trade in the neighbourhood was not brisk enough to allow them to keep an assistant. The brothers had worked amicably in this small room for twenty years, and were reported by the denizens of that quarter of Paris to be enormously rich. They were certainly contented enough, and had plenty of money for their frugal wants, as well as for their occasional exceedingly mild dissipations at the neighbouring cafe. They had always a little money for the church, and a little money for charity, and no one had ever heard either of them speak a harsh word to any living soul, and least of all to each other. When the sensitively adjusted bell at the door announced the arrival of a possible customer, Adolph left his work and attended to the shop, while Alphonse continued his task without interruption. The former was supposed to be the better business man of the two, while the latter was admittedly the better workman. They had a room over the shop, and a small kitchen over the workroom at the back; but only one occupied the bedroom above, the other sleeping in the shop, as it was supposed that the wares there displayed must have formed an almost irresistible temptation to any thief desirous of accumulating a quantity of time-pieces. The brothers took week-about at guarding the treasures below, but in all the twenty years no thief had yet disturbed their slumbers.

One evening, just as they were about to close the shop and adjourn together to the cafe, the bell rang, and Adolph went forward to learn what was wanted. He found waiting for him an unkempt individual of appearance so disreputable, that he at once made up his mind that here at last was the thief for whom they had waited so long in vain. The man's wild, roving eye, that seemed to search out every corner and cranny in the place and rest nowhere for longer than a second at a time, added to Delore's suspicions. The unsavoury visitor was evidently spying out the land, and Adolph felt certain he would do no business with him at that particular hour, whatever might happen later.

The customer took from under his coat, after a furtive glance at the door of the back room, a small paper-covered parcel, and, untying the string somewhat hurriedly, displayed a crude piece of clockwork made of brass. Handing it to Adolph, he said, "How much would it cost to make a dozen like that?"

Adolph took the piece of machinery in his hand and examined it. It was slightly concave in shape, and among the wheels was a strong spring. Adolph wound up this spring, but so loosely was the machinery put together that when he let go the key, the spring quickly uncoiled itself with a whirring noise of the wheels.

"This is very bad workmanship," said Adolph.

"It is," replied the man, who, notwithstanding his poverty-stricken appearance, spoke like a person of education. "That is why I come to you for better workmanship."

"What is it used for?"

The man hesitated for a moment. "It is part of a clock," he said at last.

"I don't understand it. I never saw a clock made like this."

"It is an alarm attachment," replied the visitor, with some impatience. "It is not necessary that you should understand it. All I ask is, can you duplicate it and at what price?"

"But why not make the alarm machinery part of the clock? It would be much cheaper than to make this and then attach it to a clock."

The man made a gesture of annoyance.

"Will you answer my question?" he said gruffly.

"I don't believe you want this as part of a clock. In fact, I think I can guess why you came in here," replied Adolph, as innocent as a child of any correct suspicion of what the man was, thinking him merely a thief, and hoping to frighten him by this hint of his own shrewdness.

His visitor looked loweringly at him, and then with a quick eye, seemed to measure the distance from where he stood to the pavement, evidently meditating flight.

"I will see what my brother says about this," said Adolph. But before Adolph could call his brother, the man bolted and was gone in an instant, leaving the mechanism in the hands of the bewildered clockmaker.

Alphonse, when he heard the story of their belated customer, was even more convinced than his brother of the danger of the situation. The man was undoubtedly a thief, and the bit of clockwork merely an excuse for getting inside the fortress. The brothers, with much perturbation, locked up the establishment, and instead of going to their usual cafe, they betook themselves as speedily as possible to the office of the police, where they told their suspicions and gave a description of the supposed culprit. The officer seemed much impressed by their story.

"Have you brought with you the machine he showed you?"

"No. It is at the shop," said Adolph. "It was merely an excuse to get inside, I am sure of that, for no clockmaker ever made it."

"Perhaps," replied the officer. "Will you go and bring it? Say nothing of this to any one you meet, but wrap the machine in paper and bring it as quickly and as quietly as you can. I would send a man with you, only I do not wish to attract attention."

Before morning the man, who gave his name as Jacques Picard, was arrested, but the authorities made little by their zeal. Adolph Delore swore positively that Picard and his visitor were the same person, but the prisoner had no difficulty in proving that he was in a cafe two miles away at the time the visitor was in Delore's shop, while Adolph had to admit that the shop was rather dark when the conversation about the clockwork took place. Picard was ably defended, and his advocate submitted that, even if he had been in the shop as stated by Delore, and had bargained as alleged for the mechanism, there was nothing criminal in that, unless the prosecution could show that he intended to put what he bought to improper uses. As well arrest a man who entered to buy a key for his watch. So Picard was released, although the police, certain he was one of the men they wanted, resolved to keep a close watch on his future movements. But the suspected man, as if to save them unnecessary trouble, left two days later for London, and there remained.

For a week Adolph slept badly in the shop, for although he hoped the thief had been frightened away by the proceedings taken against him, still, whenever he fell asleep, he dreamt of burglars, and so awoke himself many times during the long nights.

When it came the turn of Alphonse to sleep in the shop, Adolph hoped for an undisturbed night's rest in the room above, but the Fates were against him. Shortly after midnight he was flung from his bed to the floor, and he felt the house rocking as if an earthquake had passed under Paris. He got on his hands and knees in a dazed condition, with a roar as of thunder in his ears, mingled with the sharp crackle of breaking glass. He made his way to the window, wondering whether he was asleep or awake, and found the window shattered. The moonlight poured into the deserted street, and he noticed a cloud of dust and smoke rising from the front of the shop. He groped his way through the darkness towards the stairway and went down, calling his brother's name; but the lower part of the stair had been blown away, and he fell upon the debris below, lying there half- stunned, enveloped in suffocating smoke.

When Adolph partially recovered consciousness, he became aware that two men were helping him out over the ruins of the shattered shop. He was still murmuring the name of his brother, and they were telling him, in a reassuring tone, that everything was all right, although he vaguely felt that what they said was not true. They had their arms linked in his, and he stumbled helplessly among the wreckage, seeming to have lost control over his limbs. He saw that the whole front of the shop was gone, and noticed through the wide opening that a crowd stood in the street, kept back by the police. He wondered why he had not seen all these people when he looked out of the shattered window. When they brought him to the ambulance, he resisted slightly, saying he wanted to go to his brother's assistance, who was sleeping in the shop, but with gentle force they placed him in the vehicle, and he was driven away to the hospital.

For several days Adolph fancied that he was dreaming, that he would soon awake and take up again the old pleasant, industrious life. It was the nurse who told him he would never see his brother again, adding by way of consolation that death had been painless and instant, that the funeral had been one of the grandest that quarter of Paris had ever seen, naming many high and important officials who had attended it. Adolph turned his face to the wall and groaned. His frightful dream was to last him his life.

When he trod the streets of Paris a week later, he was but the shadow of his former portly self. He was gaunt and haggard, his clothes hanging on him as if they had been made for some other man, a fortnight's stubby beard on the face which had always heretofore been smoothly shaven. He sat silently at the cafe, and few of his friends recognised him at first. They heard he had received ample compensation from the Government, and now would have money enough to suffice him all his life, without the necessity of working for it, and they looked on him as a fortunate man. But he sat there listlessly, receiving their congratulations or condolences with equal apathy. Once he walked past the shop. The front was boarded up, and glass had been put in the upper windows.

He wandered aimlessly through the streets of Paris, some saying he was insane, and that he was looking for his brother; others, that he was searching for the murderer. One day he entered the police-office where he had first made his unlucky complaint.

"Have you arrested him yet?" he asked of the officer in charge.

"Whom?" inquired the officer, not recognising his visitor.

"Picard. I am Adolph Delore."

"It was not Picard who committed the crime. He was in London at the time, and is there still."

"Ah! He said he was in the north of Paris when he was with me in the south. He is a liar. He blew up the shop."

"I quite believe he planned it, but the deed was done by another. It was done by Lamoine, who left for Brussels next morning and went to London by way of Antwerp. He is living with Picard in London at this moment."

"If you know that, why has neither of them been taken?"

"To know is one thing; to be able to prove quite another. We cannot get these rascals from England merely on suspicion, and they will take good care not to set foot in France for some time to come."

"You are waiting for evidence, then?"

"We are waiting for evidence."

"How do you expect to get it?"

"We are having them watched. They are very quiet just now, but it won't be for long. Picard is too restless. Then we may arrest some one soon who will confess."

"Perhaps I could help. I am going to London. Will you give me Picard's address?"

"Here is his address, but I think you had better leave the case alone. You do not know the language, and you may merely arouse his suspicions if you interfere. Still, if you learn anything, communicate with me."

The former frank, honest expression in Adolph's eyes had given place to a look of cunning, that appealed to the instincts of a French police- officer. He thought something might come of this, and his instincts did not mislead him.

Delore with great craftiness watched the door of the house in London, taking care that no one should suspect his purpose. He saw Picard come out alone on several occasions, and once with another of his own stripe, whom he took to be Lamoine.

One evening, when crossing Leicester Square, Picard was accosted by a stranger in his own language. Looking round with a start, he saw at his side a cringing tramp, worse than shabbily dressed.

"What did you say?" asked Picard, with a tremor in his voice.

"Could you assist a poor countryman?" whined Delore.

"I have no money."

"Perhaps you could help me to get work. I don't know the language, but I am a good workman."

"How can I help you to work? I have no work myself."

"I would be willing to work for nothing, if I could get a place to sleep in and something to eat."

"Why don't you steal? I would if I were hungry. What are you afraid of? Prison? It is no worse than tramping the streets hungry; I know, for I have tried both. What is your trade?"

"I am a watchmaker and a first-class workman, but I have pawned all my tools. I have tramped from Lyons, but there is nothing doing in my trade."

Picard looked at him suspiciously for a few moments.

"Why did you accost me?" he asked at last.

"I saw you were a fellow-countryman; Frenchmen have helped me from time to time."

"Let us sit down on this bench. What is your name, and how long have you been in England?"

"My name is Adolph Carrier, and I have been in London three months."

"So long as that? How have you lived all that time?"

"Very poorly, as you may see. I sometimes get scraps from the French restaurants, and I sleep where I can."

"Well, I think I can do better than that for you. Come with me."

Picard took Delore to his house, letting himself in with a latchkey. Nobody seemed to occupy the place but himself and Lamoine. He led the way to the top story, and opened a door that communicated with a room entirely bare of furniture. Leaving Adolph there, Picard went downstairs again and came up shortly after with a lighted candle in his hand, followed by Lamoine, who carried a mattress.

"This will do for you for tonight," said Picard, "and tomorrow we will see if we can get you any work. Can you make clocks?"

"Oh yes, and good ones."

"Very well. Give me a list of the tools and materials you need and I will get them for you."

Picard wrote in a note-book the items Adolph recited to him, Lamoine watching their new employee closely, but saying nothing. Next day a table and a chair were put into the room, and in the afternoon Picard brought in the tools and some sheets of brass.

Picard and Lamoine were somewhat suspicious of their recruit at first, but he went on industriously with his task, and made no attempt to communicate with anybody. They soon saw that he was an expert workman, and a quiet, innocent, half-daft, harmless creature, so he was given other things to do, such as cleaning up their rooms and going errands for beer and other necessities of life.

When Adolph finished his first machine, he took it down to them and exhibited it with pardonable pride. There was a dial on it exactly like a clock, although it had but one hand.

"Let us see it work," said Picard; "set it so that the bell will ring in three minutes."

Adolph did as requested, and stood back when the machine began to work with a scarcely audible tick-tick. Picard pulled out his watch, and exactly at the third minute the hammer fell on the bell. "That is very satisfactory," said Picard; "now, can you make the next one slightly concave, so that a man may strap it under his coat without attracting attention? Such a shape is useful when passing the Customs."

"I can make it any shape you like, and thinner than this one if you wish it."

"Very well. Go out and get us a quart of beer, and we will drink to your success. Here is the money."

Adolph obeyed with his usual docility, staying out, however, somewhat longer than usual. Picard, impatient at the delay, spoke roughly to him when he returned, and ordered him to go upstairs to his work. Adolph departed meekly, leaving them to their beer.

"See that you understand that machine, Lamoine," said Picard. "Set it at half an hour."

Lamoine, turning the hand to the figure VI on the dial, set the works in motion, and to the accompaniment of its quiet tick-tick they drank their beer.

"He seems to understand his business," said Lamoine.

"Yes," answered Picard. "What heady stuff this English beer is. I wish we had some good French bock; this makes me drowsy."

Lamoine did not answer; he was nodding in his chair. Picard threw himself down on his mattress in one corner of the room; Lamoine, when he slipped from his chair, muttered an oath, and lay where he fell.

Twenty minutes later the door stealthily opened, and Adolph's head cautiously reconnoitred the situation, coming into the silent apartment inch by inch, his crafty eyes rapidly searching the room and filling with malicious glee when he saw that everything was as he had planned. He entered quietly and closed the door softly behind him. He had a great coil of thin strong cord in his hand. Approaching the sleeping men on tiptoe, he looked down on them for a moment, wondering whether the drug had done its work sufficiently well for him to proceed. The question was settled for him with a suddenness that nearly unnerved him. An appalling clang of the bell, a startling sound that seemed loud enough to wake the dead, made him spring nearly to the ceiling. He dropped his rope and clung to the door in a panic of dread, his palpitating heart nearly suffocating him with its wild beating, staring with affrighted eyes at the machine which had given such an unexpected alarm. Slowly recovering command over himself, he turned his gaze on the sleepers: neither had moved; both were breathing as heavily as ever.

Pulling himself together, he turned his attention first to Picard, as the more dangerous man of the two, should an awakening come before he was ready for it. He bound Picard's wrists tightly together; then his ankles, his knees, and his elbows. He next did the same for Lamoine. With great effort he got Picard in a seated position on his chair, tying him there with coil after coil of the cord. So anxious was he to make everything secure, that he somewhat overdid the business, making the two seem like seated mummies swathed in cord. The chairs he fastened immovably to the floor, then he stood back and gazed with a sigh at the two grim seated figures, with their heads drooping helplessly forward on their corded breasts, looking like silent effigies of the dead.

Mopping his perspiring brow, Adolph now turned his attention to the machine that had startled him so when he first came in. He examined minutely its mechanism to see that everything was right. Going to the cupboard, he took up a false bottom and lifted carefully out a number of dynamite cartridges that the two sleepers had stolen from a French mine. These he arranged in a battery, tying them together. He raised the hammer of the machine, and set the hand so that the blow would fall in sixty minutes after the machinery was set in motion. The whole deadly combination he placed on a small table, which he shoved close in front of the two sleeping men. This done, he sat down on a chair patiently to await the awakening. The room was situated at the back of the house, and was almost painfully still, not a sound from the street penetrating to it. The candle burnt low, guttered and went out, but Adolph sat there and did not light another. The room was still only half in darkness, for the moon shone brightly in at the window, reminding Adolph that it was just a month since he had looked out on a moonlit street in Paris, while his brother lay murdered in the room below. The hours dragged along, and Adolph sat as immovable as the two figures before him. The square of moonlight, slowly moving, at last illuminated the seated form of Picard, imperceptibly climbing up, as the moon sank, until it touched his face. He threw his head first to one side, then back, yawned, drew a deep breath, and tried to struggle.

"Lamoine," he cried "Adolph. What the devil is this? I say, here. Help! I am betrayed."

"Hush," said Adolph, quietly. "Do not cry so loud. You will wake Lamoine, who is beside you. I am here; wait till I light a candle, the moonlight is waning."

"Adolph, you fiend, you are in league with the police."

"No, I am not. I will explain everything in a moment. Have patience." Adolph lit a candle, and Picard, rolling his eyes, saw that the slowly awakening Lamoine was bound like himself.

Lamoine, glaring at his partner and not understanding what had happened, hissed--

"You have turned traitor, Picard; you have informed, curse you!"

"Keep quiet, you fool. Don't you see I am bound as tightly as you?"

"There has been no traitor and no informing, nor need of any. A month ago tonight, Picard, there was blown into eternity a good and honest man, who never harmed you or any one. I am his brother. I am Adolph Delore, who refused to make your infernal machine for you. I am much changed since then; but perhaps now you recognise me?"

"I swear to God," cried Picard, "that I did not do it. I was in London at the time. I can prove it. There is no use in handing me over to the police, even though, perhaps, you think you can terrorise this poor wretch into lying against me."

"Pray to the God, whose name you so lightly use, that the police you fear may get you before I have done with you. In the police, strange as it may sound to you, is your only hope; but they will have to come quickly if they are to save you. Picard, you have lived, perhaps, thirty-five years on this earth. The next hour of your life will be longer to you than all these years."

Adolph put the percussion cap in its place and started the mechanism. For a few moments its quiet tick-tick was the only sound heard in the room, the two bound men staring with wide-open eyes at the dial of the clock, while the whole horror of their position slowly broke upon them.

Tick-tick, tick-tick, tick-tick, tick-tick, tick-tick, tick-tick. Each man's face paled, and rivulets of sweat ran down from their brows. Suddenly Picard raised his voice in an unearthly shriek.

"I expected that," said Adolph, quietly. "I don't think anyone can hear, but I will gag you both, so that no risks may be run." When this was done, he said: "I have set the clockwork at sixty minutes; seven of those are already spent. There is still time enough left for meditation and repentance. I place the candle here so that its rays will shine upon the dial. When you have made your own peace, pray for the souls of any you have sent into eternity without time for preparation."

Delore left the room as softly as he had entered it, and the doomed men tried ineffectually to cry out as they heard the key turning in the door.

The authorities knew that someone had perished in that explosion, but whether it was one man or two they could not tell.