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 cafe door Dupre launched his bomb out
into the night.

[Illustration: DUPRE 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. Dupre 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 cafe 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 Dupre, as he rapidly pulled in the cord. It was
shrivelled at the end. Dupre 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 D