Once again a thorough search had been made during the afternoon, with no better results than before.  But it was decided that all the men should keep awake.  If the letter was delivered anywhere in the big room, they wanted to know and they meant to know who brought it.  The police do not recognize miracles.

At twelve o’clock M. Desmalions had coffee served to his subordinates.  He himself took two cups and never ceased walking from one end to the other of the room, or climbing the staircase that led to the attic, or going through the passage and hall.  Preferring that the watch should be maintained under the most favourable conditions, he left all the doors opened and all the electric lights on.

Mazeroux objected: 

“It has to be dark for the letter to come.  You will remember, Monsieur le Prefet, that the other experiment was tried before and the letter was not delivered.”

“We will try it again,” replied M. Desmalions, who, in spite of everything, was really afraid of Don Luis’s interference, and increased his measures to make it impossible.

Meanwhile, as the night wore on, the minds of all those present became impatient.  Prepared for the angry struggle as they were, they longed for the opportunity to show their strength.  They made desperate use of their ears and eyes.

At one o’clock there was an alarm that showed the pitch which the nervous tension had reached.  A shot was fired on the first floor, followed by shouts.  On inquiry, it was found that two detectives, meeting in the course of a round, had not recognized each other, and one of them had discharged his revolver in the air to inform his comrades.

In the meantime the crowd outside had diminished, as M. Desmalions perceived on opening the garden gate.  The orders had been relaxed and sightseers were allowed to come nearer, though they were still kept at a distance from the pavement.

Mazeroux said: 

“It is a good thing that the explosion is due in ten days’ time and not to-night, Monsieur le Prefet; otherwise, all those good people would be in danger as well as ourselves.”

“There will be no explosion in ten days’ time, any more than there will be a letter to-night,” said M. Desmalions, shrugging his shoulders.  And he added, “Besides, on that day, the orders will be strict.”

It was now ten minutes past two.

At twenty-five minutes past, as the Prefect was lighting a cigar, the chief detective ventured to joke: 

“That’s something you will have to do without, next time, Monsieur le Prefet.  It would be too risky.”

“Next time,” said M. Desmalions, “I shall not waste time in keeping watch.  For I really begin to think that all this business with the letters is over.”

“You can never tell,” suggested Mazeroux.

A few minutes more passed.  M. Desmalions had sat down.  The others also were seated.  No one spoke.