The next morning Mr. Gryce received a small communication from Miss Butterworth at or near the very time she received one from him. Hers ran:

His was equally laconic:

Of the two letters the latter naturally occasioned the greater excitement in the recipient. The complacency of Miss Butterworth was superb, and being the result of something that could not be communicated to those about her, occasioned in the household much speculation as to its cause.

At Police Headquarters more than one man was kept busy listening to the idle tales of a crowd of would-be informers. The results which had failed to follow the first day's publication of the crime came rapidly in during the second. There were innumerable persons of all ages and conditions who were ready to tell how they had seen this and that one issue from Mr. Adams's house on the afternoon of his death, but when asked to give a description of these persons, lost themselves in generalities as tedious as they were unprofitable. One garrulous old woman had observed a lady of genteel appearance open the door to an elderly gentleman in a great-coat; and a fashionably dressed young woman came in all breathless to relate how a young man with a very pale young lady on his arm ran against her as she was going by this house at the very hour Mr. Adams was said to have been murdered. She could not be sure of knowing the young man again, and could not say if the young lady was blonde or brunette, only that she was awfully pale and had a beautiful gray feather in her hat.

Others were ready with similar stories, which confirmed, without adding to, the facts already known, and night came on without much progress having been made toward the unravelling of this formidable mystery.

On the next day Mr. Adams's funeral took place. No relatives or intimate friends having come forward, his landlord attended to these rites and his banker acted the part of chief mourner. As his body was carried out of the house, a half-dozen detectives mingled with the crowd blocking the thoroughfare in front, but nothing came of their surveillance here or at the cemetery to which the remains were speedily carried. The problem which had been presented to the police had to be worked out from such material as had already come to hand; and, in forcible recognition of this fact, Mr. Gryce excused himself one evening at Headquarters and proceeded quite alone and on foot to the dark and apparently closed house in which the tragedy had occurred.

He entered with a key, and once inside, proceeded to light up the whole house. This done, he took a look at the study, saw that the cross had been replaced on the wall, the bird-cage rehung on its hook under the ceiling, and everything put in its wonted order, with the exception of the broken casings, which still yawned in a state of disrepair on either side of the doorway leading into the study. The steel plate had been shoved back into the place prepared for it by Mr. Adams, but the glimpses still to be seen of its blue surface through the hole made in the wall of the antechamber formed anything but an attractive feature in the scene, and Mr. Gryce, with something of the instinct and much of the deftness of a housewife, proceeded to pull up a couple of rugs from the parlor floor and string them over these openings. Then he consulted his watch, and finding that it was within an hour of nine o'clock, took up his stand behind the curtains of the parlor window. Soon, for the person expected was as prompt as himself, he saw a carriage stop and a lady alight, and he hastened to the front door to receive her. It was Miss Butterworth.

"Madam, your punctuality is equal to my own," said he. "Have you ordered your coachman to drive away?"

"Only as far as the corner," she returned, as she followed him down the hall. "There he will await the call of your whistle."

"Nothing could be better. Are you afraid to remain for a moment alone, while I watch from the window the arrival of the other persons we expect? At present there is no one in the house but ourselves."

"If I was subject to fear in a matter of this kind, I should not be here at all. Besides, the house is very cheerfully lighted. I see you have chosen a crimson light for illuminating the study."

"Because a crimson light was burning when Mr. Adams died."

"Remember Evelyn!" called out a voice.

"Oh, you have brought back the bird!" exclaimed Miss Butterworth. "That is not the cry with which it greeted me before. It was 'Eva! Lovely Eva!' Do you suppose Eva and Evelyn are the same?"

"Madam, we have so many riddles before us that we will let this one go for the present. I expect Mr. Adams's valet here in a moment."

"Sir, you relieve me of an immense weight. I was afraid that the privilege of being present at the test you propose to make was not to be accorded me."

"Miss Butterworth, you have earned a seat at this experiment. Bartow has been given a key, and will enter as of old in entire freedom to do as he wills. We have simply to watch his movements."

"In this room, sir? I do not think I shall like that. I had rather not meet this madman face to face."

"You will not be called upon to do so. We do not wish him to be startled by encountering any watchful eye. Irresponsible as he is, he must be allowed to move about without anything to distract his attention. Nothing must stand in the way of his following those impulses which may yield us a clew to his habits and the ways of this peculiar household. I propose to place you where the chances are least in favor of your being seen by him—in this parlor, madam, which we have every reason to believe was seldom opened during Mr. Adams's lifetime."

"You must put out the gas, then, or the unaccustomed light will attract his attention."

"I will not only put out the gas, but I will draw the portiÈres close, making this little hole for your eye and this one for mine. A common expedient, madam; but serviceable, madam, serviceable."

The snort which Miss Butterworth gave as she thus found herself drawn up in darkness before a curtain, in company with this plausible old man, but feebly conveyed her sensations, which were naturally complex and a little puzzling to herself. Had she been the possessor of a lively curiosity (but we know from her own lips that she was not), she might have found some enjoyment in the situation. But being where she was solely from a sense of duty, she probably blushed behind her screen at the position in which she found herself, in the cause of truth and justice; or would have done so if the opening of the front door at that moment had not told her that the critical moment had arrived and that the deaf-and-dumb valet had just been introduced into the house.

The faintest "Hush!" from Mr. Gryce warned her that her surmise was correct, and, bending her every energy to listen, she watched for the expected appearance of this man in the antechamber of Mr. Adams's former study.

He came even sooner than she was prepared to see him, and laying down his hat on a table near the doorway, advanced with a busy air toward the portiÈre he had doubtless been in the habit of lifting twenty times a day. But he barely touched it this time. Something seen, or unseen, prevented him from entering. Was it the memory of what he had last beheld there? Or had he noticed the rugs hanging in an unaccustomed way on either side of the damaged casings? Neither, apparently, for he simply turned away with a meek look, wholly mechanical, and taking up his hat again, left the antechamber and proceeded softly upstairs.

"I will follow him," whispered Mr. Gryce. "Don't be afraid, ma'am. This whistle will bring a man in from the street at once."

"I am not afraid. I would be ashamed——"

But it was useless for her to finish this disclaimer. Mr. Gryce was already in the hall. He returned speedily, and saying that the experiment was likely to be a failure, as the old man had gone to his own room and was preparing himself for bed, he led the way into the study, and with purpose, or without a purpose—who knows?—idly touched a button on the table top, thus throwing a new light on the scene. It was Miss Butterworth's first experience of this change of light, and she was observing the effect made by the violet glow now thrown over the picture and the other rich articles in the room when her admiration was cut short, and Mr. Gryce's half-uttered remark also, by the faint sound of the valet's descending steps.

Indeed, they had barely time to regain their old position behind the parlor portiÈres when Bartow was seen hurrying in from the hall with his former busy air, which this time remained unchecked.

Crossing to his master's study, he paused for an infinitesimal length of time on the threshold, as if conscious of something being amiss, then went into the room beyond, and, without a glance in the direction of the rug, which had been carefully relaid on the spot where his master had fallen, began to make such arrangements for the night as he was in the habit of making at this hour. He brought a bottle of wine from the cupboard and set it on the table, and then a glass, which he first wiped scrupulously clean. Then he took out his master's dressing gown and slippers, and, placing them to hand, went into the bedroom.

By this time the two watchers had crept from their concealment near enough to note what he was doing in the bedroom. He was stooping over the comb which Mr. Gryce had left lying on the floor. This small object in such a place seemed to surprise him. He took it up, shook his head, and put it back on the dresser. Then he turned down his master's bed.

"Poor fool!" murmured Miss Butterworth as she and her companion crept back to their old place behind the parlor curtains, "he has forgotten everything but his old routine duties. We shall get nothing from this man."

But she stopped suddenly; they both stopped. Bartow was in the middle of the study, with his eyes fixed on his master's empty chair in an inquiring way that spoke volumes. Then he turned, and gazed earnestly at the rug where he had last seen that master lying outstretched and breathless; and awakening to a realization of what had happened, fell into his most violent self and proceeded to go through the series of actions which they were now bound to consider a reproduction of what he had previously seen take place there. Then he went softly out, and crept away upstairs.

Mr. Gryce and Miss Butterworth stepped at once into the light, and surveyed each other with a look of marked discouragement. Then the latter, with a sudden gleam of enthusiasm, cried quickly:

"Turn on another color, and let us see what will happen. I have an idea it will fetch the old man down again."

Mr. Gryce's brows went up.

"Do you think he can see through the floor?"

But he touched a button, and a rich blue took the place of the violet.

Nothing happened.

Miss Butterworth looked disturbed.

"I have confidence in your theories," began Mr. Gryce, "but when they imply the possibility of this man seeing through blank walls and obeying signals which can have no signification to any one on the floor above——"

"Hark!" she cried, holding up one finger with a triumphant air. The old man's steps could be heard descending.

This time he approached with considerable feebleness, passed slowly into the study, advanced to the table, and reached out his hands as if to lift something which he expected to find there. Seeing nothing, he glanced in astonishment up at the book shelves and then back to the table, shook his head, and suddenly collapsing, sank in a doze on the nearest chair.

Miss Butterworth drew a long breath, eyed Mr. Gryce with some curiosity, and then triumphantly exclaimed:

"Can you read the meaning of all that? I think I can. Don't you see that he came expecting to find a pile of books on the table which it was probably his business to restore to their shelves?"

"But how can he know what light is burning here? You can see for yourself that there is no possible communication between this room and the one in which he has always been found by any one going above."

Miss Butterworth's manner showed a hesitation that was almost naive. She smiled, and there was apology in her smile, though none in her voice, as she remarked with odd breaks:

"When I went upstairs—you know I went upstairs when I was here before—I saw a little thing—a very little thing—which you doubtless observed yourself and which may explain, though I do not know how, why Bartow can perceive these lights from the floor above."

"I shall be very glad to hear about it, madam. I thought I had thoroughly searched those rooms——"

"And the halls?"

"And the halls; and that nothing in them could have escaped my eyes. But if you have a more patient vision than myself——"

"Or make it my business to look lower——"

"How?"

"To look lower; to look on the floor, say."

"On the floor?"

"The floor sometimes reveals much: shows where a person steps the oftenest, and, therefore, where he has the most business. You must have noticed how marred the woodwork is at the edge of the carpeting on that little landing above."

"In the round of the staircase?"

"Yes."

Mr. Gryce did not think it worth his while to answer. Perhaps he had not time; for leaving the valet where he was, and Miss Butterworth where she was (only she would not be left, but followed him), he made his way upstairs, and paused at the place she had mentioned, with a curious look at the floor.

"You see, it has been much trodden here," she said; at which gentle reminder of her presence he gave a start; possibly he had not heard her behind him, and after sixty years of hard service even a detective may be excused a slight nervousness. "Now, why should it be trodden here? There is no apparent reason why any one should shuffle to and fro in this corner. The stair is wide, especially here, and there is no window——"

Mr. Gryce, whose eye had been travelling over the wall, reached over her shoulder to one of the dozen pictures hanging at intervals from the bottom to the top of the staircase, and pulling it away from the wall, on which it hung decidedly askew, revealed a round opening through which poured a ray of blue light which could only proceed from the vault of the adjoining study.

"No window," he repeated. "No, but an opening into the study wall which answers the same purpose. Miss Butterworth, your eye is to be trusted every time. I only wonder you did not pull this picture aside yourself."

"It was not hanging crooked then. Besides I was in a hurry. I had just come from my encounter with this demented man. I had noticed the marks on the landing, and the worn edges of the carpet, on my way upstairs. I was in no condition to observe them on my way down."

"I see."

Miss Butterworth ran her foot to and fro over the flooring they were examining.

"Bartow was evidently in the habit of coming here constantly," said she, "probably to learn whether his master had need of him. Ingenious in Mr. Adams to contrive signals for communication with this man! He certainly had great use for his deaf-and-dumb servant. So one mystery is solved!"

"And if I am not mistaken, we can by a glance through this loophole obtain the answer to another. You are wondering, I believe, how Bartow, if he followed the movements of the assailant from the doorway, came to thrust with his left hand, instead of with his right. Now if he saw the tragedy from this point, he saw it over the assailant's shoulder, instead of face to face. What follows? He would imitate literally the movements of the man he saw, turn in the same direction and strike with the same hand."

"Mr. Gryce, we are beginning to untangle the threads that looked so complicated. Ah, what is that? Why, it's that bird! His cage must be very nearly under this hole."

"A little to one side, madam, but near enough to give you a start. What was it he cried then?"

"Oh, those sympathetic words about Eva! 'Poor Eva!'"

"Well, give a glance to Bartow. You can see him very well from here."

Miss Butterworth put her eye again to the opening, and gave a grunt, a very decided grunt. With her a grunt was significant of surprise.

"He is shaking his fist; he is all alive with passion. He looks as if he would like to kill the bird."

"Perhaps that is why the creature was strung up so high. You may be sure Mr. Adams had some basis for his idiosyncrasies."

"I begin to think so. I don't know that I care to go back where that man is. He has a very murderous look."

"And a very feeble arm, Miss Butterworth. You are safe under my protection. My arm is not feeble."

[Illustration: A-Table. B-Small Stand. C-Door to Bedroom. D-Evelyn's Picture E-Loophole on Stair Landing. F-Entrance to Study.] [1]