“He is sweeping the library.”

“Then you must not go down,” cried Bessie, sitting up, and losing her fear for a moment in her anxiety for her husband’s safety.  “A burglar you might manage, but a maniac—­”

“I must go, Bess,” said Thaddeus, firmly.

“Then I’m going with you,” said Mrs. Perkins, with equal firmness.

“Now, Bess, don’t be foolish,” returned Thaddeus, his face assuming a graver expression than his wife had ever seen there.  “This is my work, and it is none of yours.  I positively forbid you to stir out of this room.  I shall be very careful, and you need have no concern for me.  I shall go down the backstairs and around by the porch, and peep in through the library window first.  The moonlight will be sufficient to enable me to see all that is necessary.”

“Very well,” acquiesced Bessie, “only do be careful.”

Thaddeus donned his long bath-robe, put on his slippers, and started to descend.  The stairs were so dark that he could with difficulty proceed—­and perhaps it was just as well for Thaddeus that they were.  If there had been light enough for him to see two great glaring eyes that stared at him through that darkness out from the passageway at the foot of the stairs, upon which he turned his back when he went out upon the porch, it is not unlikely that a very serious climax to his strange experience would have been reached then and there.  As it was, he saw nothing, but kept straight ahead, stepped noiselessly out upon the piazza, crept stealthily along in the soft light of the moon, until he reached the library window.  There he stopped and listened.  All was still within—­so still that the beating of his heart seemed like the hammering of a sledge upon an anvil by contrast.  Then, raising himself cautiously upon his toes, he peered through the window into the room, the greater part of which was made visible by the wealth of the moon’s light streaming into it.

“Humph!” said Thaddeus, after he had directed his searching gaze into every corner.  “There isn’t anybody there at all.  Most incomprehensible thing I ever heard of.”

Rising, he walked back to the piazza door, and went thence boldly into the library and lit the gas.  His piazza observations were then verified, for the room was devoid of life, save for Thaddeus’s own presence; but upon the floor before the hearth was a broom, and there were evidences also that the sweeping sounds he had heard had been caused by no less an instrument than this, for in the corner of the fireplace was a heap of dust, cigar ashes, and scraps of paper, which Thaddeus remembered had been upon the hearth in greater or less quantity when he had turned out the gas to retire a few hours before.

“This is a serious matter,” he said to himself.  “Something is wrong, and I doubt if there have been burglars in the house; but I can ascertain that without trouble.  If the doors and windows are all secure the trouble is internal.”