In our room we worked far into the night. Craig carefully swabbed out the bottom and sides of each bottle by inserting a little piece of cotton on the end of a long wire. Then he squeezed the water out of the cotton swab on small gla.s.s slides coated with agar-agar, or j.a.panese seaweed, a medium in which germ-cultures multiply rapidly. He put the slides away in a little oven with an alcohol-lamp which he had brought along, leaving them to remain overnight at blood heat.

I had noticed all this time that he was very particular not to touch any of the bottles on the outside. As for me, I wouldn't have touched them for the world. In fact, I was getting so I hesitated to touch anything.

I was almost afraid to breathe, though I knew there was no harm in that.

However, it was not danger of infection in touching the bottles that made Craig so careful. He had noted, in the dim light of the station lamps, what seemed to be finger-marks on the bottles, and they had interested him, in fact, had decided him on a further investigation of the bottles.

"I am now going to bring out these very faint finger-prints on the bottles," remarked Craig, proceeding with his examination in the better light of our room. "Here is some powder known to chemists as 'grey powder'--mercury and chalk. I sprinkle it over the faint markings, so, and then I brush it off with a camel's-hair brush lightly. That brings out the imprint much more clearly, as you can see. For instance, if you place your dry thumb on a piece of white paper you leave no visible impression. If grey powder is sprinkled over the spot and then brushed off a distinct impression is seen. If the impression of the fingers is left on something soft, like wax, it is often best to use printers' ink to bring out the ridges and patterns of the finger-marks. And so on for various materials. Quite a science has been built up around finger-prints.

"I wish I had that enlarging camera which I have in my laboratory.

However, my ordinary camera will do, for all I want is to preserve a record of these marks, and I can enlarge the photographs later. In the morning I will photograph these marks and you can do the developing of the films. To-night we'll improvise the bathroom as a dark-room and get everything ready so that we can start in bright and early."

We were, indeed, up early. One never has difficulty in getting up early in the country: it is so noisy, at least to a city-bred man. City noise at five A.M. is sepulchral silence compared with bucolic activity at that hour.

There were a dozen negatives which I set about developing after Craig had used up all our films. Meanwhile, he busied himself adjusting his microscope and test-tubes and getting the agar slides ready for examination.

Shirt-sleeves rolled up, I was deeply immersed in my work when I heard a shout in the next room, and the bathroom door flew open.

"Confound you, Kennedy, do you want to ruin these films!" I cried.

He shut the door with a bang. "Hurrah, Walter!" he exclaimed. "I think I have it, at last. I have just found some most promising colonies of the bacilli on one of my slides."

I almost dropped the pan of acid I was holding, in my excitement.

"Well," I said, concealing my own surprise, "I've found out something, too. Every one of these finger-prints so far is from the same pair of hands."

We scarcely ate any breakfast, and were soon on our way up to the hall.

Craig had provided himself at the local stationer's with an inking-pad, such as is used for rubber stamps. At the hall he proceeded to get the impressions of the fingers and thumbs of all the servants.

It was quite a long and difficult piece of work to compare the finger-prints we had taken with those photographed, in spite of the fact that writers descant on the ease with which criminals are traced by this system devised by the famous Galton. However, we at last finished the job between us; or rather Craig finished it, with an occasional remark from me. His dexterity amazed me; it was more than mere book knowledge.

For a moment we sat regarding each other hopelessly. None of the finger-prints taken at the hall tallied with the photographed prints.

Then Craig rang for the housekeeper, a faithful old soul whom even the typhoid scare could not budge from her post.

"Are you sure I have seen all the servants who were at the hall while Mr. Bisbee was here" asked Craig.

"Why, no, sir--you didn't ask that. You asked to see all who are here now. There is only one who has left, the cook, Bridget Fallon. She left a couple of days ago--said she was going back to New York to get another job. Glad enough I was to get rid of her, too, for she was drunk most of the time after the typhoid appeared."

"Well, Walter, I guess we shall have to go back to New York again, then," exclaimed Kennedy. "Oh, I beg pardon, Mrs. Rawson, for interrupting. Thank you ever so much. Where did Bridget come from?"

"She came well recommended, sir. Here is the letter in my writing-desk.

She had been employed by the Caswell-Joneses at Shelter Island before she came here."

"I may keep this letter" asked Craig, scanning it quickly.

"Yes."

"By the way, where were the bottles of spring water kept"

"In the kitchen."

"Did Bridget take charge of them?"

"Yes."

"Did Mr. Bisbee have any guests during the last week that he was here?"

"Only Mr. Denny one night."

"H'm!" exclaimed Craig. "Well, it will not be so hard for us to unravel this matter, after all, when we get back to the city. We must make that noon train, Walter. There is nothing more for us to do here."

Emerging from the "Tube" at Ninth Street, Craig hustled me into a taxicab, and in almost no time we were at police headquarters.

Fortunately, Inspector Barney O'Connor was in and in an amiable mood, too, for Kennedy had been careful that the Central Office received a large share of credit for the Kerr Parker case. Craig sketched hastily the details of this new case. O'Connor's face was a study. His honest blue Irish eyes fairly bulged in wonder, and when Craig concluded with a request for help I think O'Connor would have given him anything in the office, just to figure in the case.

"First, I want one of your men to go to the surrogate's office and get the original of the will. I shall return it within a couple of hours--all I want to do is to make a photographic copy. Then another man must find this lawyer, James Denny, and in some way get his finger-prints--you must arrange that yourself. And send another fellow up to the employment offices on Fourth Avenue and have him locate this cook, Bridget Fallon. I want her finger-prints, too. Perhaps she had better be detained, for I don't want her to get away. Oh, and say, O'Connor, do you want to finish this case up like the crack of a whip to-night?"

"I'm game, sir. What of it?"

"Let me see. It is now four o'clock. If you can get hold of all these people in time I think I shall be ready for the final scene to-night--say, at nine. You know how to arrange it. Have them all present at my laboratory at nine, and I promise we shall have a story that will get into the morning papers with leaded type on the front page."

"Now, Walter," he added, as we hurried down to the taxicab again, "I want you to drop off at the Department of Health with this card to the commissioner. I believe you know Dr. Leslie. Well, ask him if he knows anything about this Bridget Fallon. I will go on up-town to the laboratory and get my apparatus ready. You needn't come up till nine, old fellow, for I shall be busy till then, but be sure when you come that you bring the record of this Fallon woman if you have to beg, borrow, or steal it."

I didn't understand it, but I took the card and obeyed implicitly. It is needless to say that I was keyed up to the greatest pitch of excitement during my interview with the health commissioner, when I finally got in to see him. I hadn't talked to him long before a great light struck me, and I began to see what Craig was driving at. The commissioner saw it first.

"If you don't mind, Mr. Jameson." he said, after I had told him as much of my story as I could, "will you call up Professor Kennedy and tell him I'd like very much to be present to-night myself?"

"Certainly I will," I replied, glad to get my errand done in first-cla.s.s fashion in that way.

Things must have been running smoothly, for while I was sitting in our apartment after dinner, impatiently waiting for half-past eight, when the commissioner had promised to call for me and go up to the laboratory, the telephone rang. It was Craig.

"Walter, might I ask a favour of you?" he said. "When the commissioner comes ask him to stop at the Louis Quinze and bring Miss Bisbee up, too.

Tell her it is important. No more now. Things are going ahead fine."

Promptly at nine we were a.s.sembled, a curious crowd. The health commissioner and the inspector, being members of the same political party, greeted each other by their first names. Miss Bisbee was nervous, Bridget was abusive, Denny was sullen. As for Kennedy, he was, as usual, as cool as a lump of ice. And I--well, I just sat on my feelings to keep myself quiet.

At one end of the room Craig had placed a large white sheet such as he used in his stereopticon lectures, while at the top of the tier of seats that made a sort of little amphitheatre out of his lecture-room his stereopticon sputtered.

"Moving pictures to-night, eh?" said Inspector O'Connor.

"Not exactly," said Craig, "though--yes, they will be moving in another sense. Now, if we are all ready, I'll switch off the electric lights."

The calcium sputtered some more, and a square of light was thrown on the sheet.

Kennedy snapped a little announcer such as lecturers use. "Let me invite your attention to these enlargements of finger-prints," he began, as a huge thumb appeared on the screen. "Here we have a series of finger-prints which I will show one after another slowly. They are all of the fingers of the same person, and they were found on some empty bottles of spring water used at Bisbee Hall during the two weeks previous to the departure of Mr. Bisbee for New York.

"Here are, in succession, the finger-prints of the various servants employed about the house--and of a guest," added Craig, with a slight change of tone. "They differ markedly from the finger-prints on the gla.s.s," he continued, as one after another appeared, "all except this last one. That is identical. It is, Inspector, what we call a composite type of finger-print--in this case a combination of what is called the 'loop' and 'whorl' types."

No sound broke the stillness save the sputtering of the oxygen on the calcium of the stereopticon.

"The owner of the fingers from which these prints were made is in this room. It was from typhoid germs on these fingers that the fever was introduced into the drinking water at Bisbee Hall."