death in New York and were supposed to have done so, yet you were certainly seen in the crowd which invaded that rear building at the first alarm. Are you conscious of possessing a double, or did you fail to cross the river as you expected to?"

"I am glad this has come up." The tone was one of self-congratulation which would have shaken Sweet.w.a.ter sorely had he been admitted to this unofficial examination. "I have never confided to any one the story of my doings on that unhappy afternoon, because I knew of no one who would take any interest in them. But this is what occurred. I did mean to go to New York and I even started on my walk to the Bridge at the hour mentioned. But I got into a small crowd on the corner of Fulton Street, in which a poor devil who had robbed a vendor's cart of a few oranges, was being hustled about. There was no policeman within sight, and so I busied myself there for a minute paying for the oranges and dragging the poor wretch away into an alley, where I could have the pleasure of seeing him eat them. When I came out of the alley the small crowd had vanished, but a big one was collecting up the street very near my home.

I always think of my books when I see anything suggesting fire, and naturally I returned, and equally naturally, when I heard what had happened, followed the crowd into the court and so up to the poor woman's doorway. But my curiosity satisfied, I returned at once to the street and went to New York as I had planned."

"Do you mind telling us where you went in New York?"

"Not at all. I went shopping. I wanted a certain very fine wire, for an experiment I had on hand, and I found it in a little shop in Fourth Avenue. If I remember rightly, the name over the door was Grippus. Its oddity struck me."

There was nothing left to the Inspector but to dismiss him. He had answered all questions willingly, and with a countenance inexpressive of guile. He even indulged in a parting shot on his own account, as full of frank acceptance of the situation as it was fearless in its attack.

As he halted in the doorway before turning his back upon the room, he smiled for the third time as he quietly said:

"I have ceased visiting my friend's apartment in upper New York. If you ever want me again, you will find me amongst my books. If my invention halts and other interests stale, you have furnished me this day with a problem which cannot fail to give continual occupation to my energies.

If I succeed in solving it first, I shall be happy to share my knowledge with you. Till then, trust the laws of nature. No man when once on the outside of a door can b.u.t.ton it on the inside, nor could any one without the gift of complete invisibility, make a leap of over fifteen feet from the sill of a fourth story window on to an adjacent fire escape, without attracting the attention of some of the many children playing down below."

He was half-way out the door, but his name quickly spoken by the Inspector drew him back.

"Anything more?" he asked.

The Inspector smiled.

"You are a man of considerable a.n.a.lytic power, as I take it, Mr.

Brotherson. You must have decided long ago how this woman died."

"Is that a question, Inspector?"

"You may take it as such."

"Then I will allow myself to say that there is but one common-sense view to take of the matter. Miss Challoner's death was due to suicide; so was that of the washerwoman. But there I stop. As for the means--the motive--such mysteries may be within your province but they are totally outside mine! G.o.d help us all! The world is full of misery. Again I wish you good-day."

The air seemed to have lost its vitality and the sun its sparkle when he was gone.

"Now, what do you think, Gryce?"

The old man rose and came out of his corner.

"This: that I'm up against the hardest proposition of my lifetime.

Nothing in the man's appearance or manner evinces guilt, yet I believe him guilty. I must. Not to, is to strain probability to the point of breakage. But how to reach him is a problem and one of no ordinary nature. Years ago, when I was but little older than Sweet.w.a.ter, I had just such a conviction concerning a certain man against whom I had even less to work on than we have here. A murder had been committed by an envenomed spring contained in a toy puzzle. I worked upon the conscience of the suspect in that case, by bringing constantly before his eyes a facsimile of that spring. It met him in the folded napkin which he opened at his restaurant dinner. He stumbled upon it in the street, and found it lying amongst his papers at home. I gave him no relief and finally he succ.u.mbed. He had been almost driven mad by remorse. But this man has no conscience. If he is not innocent as the day, he's as hard as unquarried marble. He might be confronted with reminders of his crime at every turn without weakening or showing by loss of appet.i.te or interrupted sleep any effect upon his nerves. That's my opinion of the gentleman. He is either that, or a man of uncommon force and self-restraint."

"I'm inclined to believe him the latter."

"And so give the whole matter the go-by?"

"Possibly."

"It will be a terrible disappointment to Sweet.w.a.ter."

"That's nothing."

"And to me."

"That's different. I'm disposed to consider you, Gryce--after all these years."

"Thank you; I have done the state some service."

"What do you want? You say the mine is unworkable."

"Yes, in a day, or in a week, possibly in a month. But persistence and a protean adaptability to meet his moods might accomplish something.

I don't say will, I only say might. If Sweet.w.a.ter had the job, with unlimited time in which to carry out any plan he may have, or even for a change of plans to suit a changed idea, success might be his, and both time, effort and outlay justified."

"The outlay? I am thinking of the outlay."

"Mr. Challoner will see to that. I have his word that no reasonable amount will daunt him."

"But this Brotherson is suspicious. He has an inventor's secret to hide, if none other. We can't saddle him with a guy of Sweet.w.a.ter's appearance and abnormal loquaciousness."

"Not readily, I own. But time will bring counsel. Are you willing to help the boy, to help me and possibly yourself by this venture in the dark? The Department shan't lose money by it; that's all I can promise."

"But it's a big one. Gryce, you shall have your way. You'll be the only loser if you fail; and you will fail; take my word for it."

"I wish I could speak as confidently to the contrary, but I can't. I can give you my hand though, Inspector, and Sweet.w.a.ter's thanks. I can meet the boy now. An hour ago I didn't know how I was to do it."

XV. THAT'S THE QUESTION

"How many times has he seen you?"

"Twice."

"So that he knows your face and figure?"

"I'm afraid so. He cannot help remembering the man who faced him in his own room."

"That's unfortunate."

"d.a.m.ned unfortunate; but one must expect some sort of a handicap in a game like this. Before I'm done with him, he'll look me full in the face and wonder if he's ever seen me before. I wasn't always a detective. I was a carpenter once, as you know, and I'll take to the tools again. As soon as I'm handy with them I'll hunt up lodgings in Hicks Street. He may suspect me at first, but he won't long; I'll be such a confounded good workman. I only wish I hadn't such p.r.o.nounced features. They've stood awfully in my way, Mr. Gryce. I don't like to talk about my appearance, but I'm so confounded plain that people remember me. Why couldn't I have had one of those putty faces which don't mean anything?

It would have been a deuced sight more convenient."

"You've done very well as it is."

"But I want to do better. I want to deceive him to his face. He's clever, this same Brotherson, and there's glory to be got in making a fool of him. Do you think it could be done with a beard? I've never worn a beard. While I'm settling back into my old trade, I can let the hair grow."

"Do. It'll make you look as weak as water. It'll be blonde, of course."

"And silky and straggling. Charming addition to my beauty. But it'll take half an inch off my nose, and it'll cover my mouth, which means a lot in my case. Then my complexion! It must be changed naturally. I'll consult a doctor about that. No sort of make-believe will go with this man. If my eyes look weak, they must really be so. If I walk slowly and speak huskily, it must be because I cannot help it. I can bear the slight inconvenience of temporary ill-health in a cause like this; and if necessary the cough will be real, and the headache positive.

"Sweet.w.a.ter! We'd better give the task to another man--to someone Brotherson has never seen and won't be suspicious of?"