He must measure the distance at night—and late at night too—he said to himself. He bought a ball of cord, as nearly the colour of the front of the building as possible. He left his window open, and after midnight ran the cord out till he estimated that it about reached the top of the café door. He stole quietly down and let himself out, leaving the door unlatched. The door to the apartments was at the extreme edge of the building, while the café doors were in the middle, with large windows on each side. As he came round to the front, his heart almost ceased to beat when a voice from the café door said—
"What do you want? What are you doing here at this hour?"
The policeman had become so much a part of the pavement in Dupré's mind that he had actually forgotten the officer was there night and day. Dupré allowed himself the luxury of one silent gasp, then his heart took up its work again.
"I was looking for you," he said quietly. By straining his eyes he noticed at the same moment that the cord dangled about a foot above the policeman's head, as he stood in the dark doorway.
"I was looking for you. I suppose you don't know of any—any chemist's shop open so late as this? I have a raging toothache and can't sleep, and I want to get something for it."
"Oh, the chemist's at the corner is open all night. Ring the bell at the right hand."
"I hate to disturb them for such a trifle."
"That's what they're there for," said the officer philosophically.
"Would you mind standing at the other door till I get back? I'll be as quick as I can. I don't wish to leave it open unprotected, and I don't want to close it, for the concierge knows I'm in and he is afraid to open it when any one rings late. You know me, of course; I'm in No. 16."
"Yes, I recognise you now, though I didn't at first. I will stand by the door until you return."
Dupré went to the corner shop and bought a bottle of toothache drops from the sleepy youth behind the counter. He roused him up however, and made him explain how the remedy was to be applied. He thanked the policeman, closed the door, and went up to his room. A second later the cord was cut at the window and quietly pulled in.
Dupré sat down and breathed hard for a few moments.
"You fool!" he said to himself; "a mistake or two like that and you are doomed. That's what comes of thinking too much on one branch of your subject. Another two feet and the string would have been down on his nose. I am certain he did not see it; I could hardly see it myself, looking for it. The guarding of the side door was an inspiration. But I must think well over every phase of the subject before acting again. This is a lesson."
As he went on with his preparations it astonished him to find how many various things had to be thought of in connexion with an apparently simple scheme, the neglect of any one of which would endanger the whole enterprise. His plan was a most uncomplicated one. All he had to do was to tie a canister of dynamite at the end of a string of suitable length, and at night, before the café doors were closed, fling it from his window so that the package would sweep in by the open door, strike against the ceiling of the café, and explode. First he thought of holding the end of the cord in his hand at the open window, but reflection showed him that if, in the natural excitement of the moment, he drew back or leant too far forward the package might strike the front of the house above the door, or perhaps hit the pavement. He therefore drove a stout nail in the window-sill and attached the end of the cord to that. Again, he had to render his canister of explosive so sensitive to any shock that he realised if he tied the cord around it and flung it out into the night the can might go off when the string was jerked tight and the explosion take place in mid-air above the street. So he arranged a spiral spring between can and cord to take up harmlessly the shock caused by the momentum of the package when the string became suddenly taut. He saw that the weak part of his project was the fact that everything would depend on his own nerve and accuracy of aim at the critical moment, and that a slight miscalculation to the right or to the left would cause the bomb, when falling down and in, to miss the door altogether. He would have but one chance, and there was no opportunity of practising. However, Dupré, who was a philosophical man, said to himself that if people allowed small technical difficulties to trouble them too much, nothing really worth doing would be accomplished in this world. He felt sure he was going to make some little mistake that would ruin all his plans, but he resolved to do the best he could and accept the consequences with all the composure at his command.
As he stood by the window on the fatal night with the canister in his hand he tried to recollect if there was anything left undone or any tracks remaining uncovered. There was no light in his room, but a fire burned in the grate, throwing flickering reflections on the opposite wall.
"There are four things I must do," he murmured: "first, pull up the string; second, throw it in the fire; third, draw out the nail; fourth, close the window."
He was pleased to notice that his heart was not beating faster than usual. "I think I have myself well in hand, yet I must not be too cool when I get downstairs. There are so many things to think of all at one time," he said to himself with a sigh. He looked up and down the street. The pavement was clear. He waited until the policeman had passed the door. He would take ten steps before he turned on his beat. When his back was towards the café door Dupré launched his bomb out into the night.
He drew back instantly and watched the nail. It held when the jerk came. A moment later the whole building lurched like a drunken man, heaving its shoulders as it were. Dupré was startled by a great square of plaster coming down on his table with a crash. Below, there was a roar of muffled thunder. The floor trembled under him after the heave. The glass in the window clattered down, and he felt the air smite him on the breast as if some one had struck him a blow.
He looked out for a moment. The concussion had extinguished the street lamps opposite. All was dark in front of the café where a moment before the Boulevard was flooded with light. A cloud of smoke was rolling out from the lower part of the house.
"Four things," said Dupré, as he rapidly pulled in the cord. It was shrivelled at the end. Dupré did the other three things quickly.
Everything was strangely silent, although the deadened roar of the explosion still sounded dully in his ears. His boots crunched on the plaster as he walked across the room and groped for the door. He had some trouble in pulling it open. It stuck so fast that he thought it was locked; then he remembered with a cold shiver of fear that the door had been unlocked all the time he had stood at the window with the canister in his hand.
"I have certainly done some careless thing like that which will betray me yet; I wonder what it is?"
He wrenched the door open at last. The lights in the hall were out; he struck a match, and made his way down. He thought he heard groans. As he went down, he found it was the concierge huddled in a corner.
"What is the matter?" he asked.
"Oh, my God, my God!" cried the concierge, "I knew they would do it. We are all blown to atoms!"
"Get up," said Dupré, "you're not hurt; come with me and see if we can be of any use."
"I'm afraid of another explosion," groaned the concierge.
"Nonsense! There's never a second. Come along."
They found some difficulty in getting outside, and then it was through a hole in the wall and not through the door. The lower hall was wrecked.
Dupré expected to find a crowd, but there was no one there. He did not realise how short a time had elapsed since the disaster. The policeman was on his hands and knees in the street, slowly getting up, like a man in a
