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 qua