"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 b.u.t.ton on the table top, thus throwing a new light on the scene. It was Miss b.u.t.terworth'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 portieres 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 gla.s.s, 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 b.u.t.terworth 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 b.u.t.terworth 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 b.u.t.ton, and a rich blue took the place of the violet.

Nothing happened.

Miss b.u.t.terworth 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, pa.s.sed 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 b.u.t.terworth 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 b.u.t.terworth'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 b.u.t.terworth 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 b.u.t.terworth, 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 b.u.t.terworth 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 a.s.sailant 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 a.s.sailant'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 b.u.t.terworth 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 pa.s.sion. 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."