Thus once again a solitary occupied the Grey Room and measured his intelligence against the terrible forces therein concealed.  Signor Mannetti took leave of them cheerfully at eight o’clock, and while Sir Walter and Mary descended to the library, Henry took up his station at the head of the staircase.  The corridor was lighted and the door of the Grey Room left open.

But in ten minutes the watcher looked out and cried to Lennox, who sat smoking about thirty-five yards from him.

“There is a great draught here,” he said.  “I will close the door, but leave it ajar that we may salute each other from time to time.”

The hours crept on and since everybody at Chadlands knew what was happening, few retired to rest.  It was understood that some time after midnight Signor Mannetti hoped to declare the result of his experiment.

Henry Lennox challenged half-hourly, always receiving a brisk reply.  But a little after half-past one his “All well, signor?” received no response.  He raised his voice, but still no answer came.  He went to the door, therefore, and looked into the Grey Room.  The watcher had slipped down in the armchair they had set for him under the electric light, and was lying motionless, but in an easy position.  He still wore his fur-coat.  Prince Henry did not see.  The room was silent and cold.  The electric light burned brightly, and both windows were open.  Young Lennox hastened downstairs.  His thoughts concentrated on his uncle, and his desire was to spare him any needless shock.  For a moment he believed that Signor Mannetti had succumbed in the Grey Room, as others before him, but he could not be certain.  A bare half-hour had elapsed since the watcher had uttered a cheerful answer to the last summons, and told them his vigil was nearly ended.  Lennox sought Masters, therefore, told him that the worst was to be feared, yet explained that the old man who had watched in the Grey Room might not be dead but sunk in sleep.

Masters was sanguine that it might be so.

“Be sure he is so.  I’ll fetch the liqueur brandy,” and, armed with his panacea, he followed Henry upstairs.  Signor Mannetti had not moved, but as they approached him, to their infinite relief he did so, opened his eyes, stared wildly about him, and then realized the situation.

“Alas!  Now I have frightened you out of your senses,” he said, looking at their anxious faces.  “All is well.  In less than another hour I should have summoned Sir Walter.  But just that last half-hour overcame me, and I sank into sleep.  What is the time?”

“A quarter to two, signor.”

“Good!  Then let your uncle be summoned.  I have found out the secret.”

“A thimbleful of old cognac, signor?” asked Masters.

“Willingly, my friend, willingly.  I see how wise you both were.  I approve and thank you.  You thought that I had followed the others into the shades, yet meant to restore me if you could without frightening Sir Walter.  To go to sleep was unpardonable.”