In the second place, the chapter of incidents seemed to have closed with the acquittal of Dave Campion and the disappearance of John Thaneford.

No word of any kind had come from the latter, and his whereabouts remained entirely unknown; it was a fair presumption that he never would reappear to trouble us. His financial affairs were hopelessly involved, and "Thane Court" itself was to be sold at public auction in February in order to satisfy the demands of the creditors.

And finally, while the young woman's conduct had been indiscreet, if not absolutely disloyal, her lesson had been an exceedingly bitter one, and it was charitable to a.s.sume that it had been taken to heart. After my marriage to Betty in December it would be time enough to consider making other arrangements. Yes, my decision was taken, and now it was necessary to communicate it to Eunice herself.

Miss Trevor listened to my proposal in stony silence, but in the first flush of my new happiness I could easily overlook even a direct ungraciousness. Mrs. Anthony was old and a semi-invalid; Betty would have her cousin's companionship during my long continued absence North, and that was enough. The upshot of our conference was that Miss Trevor agreed to stay on at the "Hundred." She admitted that the arrangement would be convenient, as the school position for which she had applied would not be available until the following September.

"Then it is settled," I concluded, with as much cordiality as I could put into my voice. "I'm trusting Betty in your hands; you'll take good care of her."

"Yes, Mr. Hildebrand, I can certainly promise to do that," she began; then she broke off and looked away as though regretting that she had said even that much.

"That's all I want," I said, "and I'm glad we understand each other." I made a half motion to offer my hand, but she did not appear to notice the gesture, and we parted. Again I felt a twinge of disquietude, but the affair had been decided, and it was too late to reopen the discussion. A strange creature was Eunice Trevor, but I believe even now that she did love Betty Graeme. If only she had never looked into John Thaneford's baleful black eyes!

As I have said before, my marriage to Betty took place in the last part of December. We went to Aiken for the honeymoon, intending to be back at the "Hundred" for the Christmas holidays. But we had been gone only four days when we were recalled by Mrs. Anthony's fatal attack of pneumonia. She died on December the twenty-third, and the holly wreaths and mistletoe remained unhung for our first Christmas in the old homestead, while the festivities of the season had to be confined to the servants' hall and the quarters. But we had Chalmers Warriner and Doctor Marcy in for dinner, and in my heart of hearts I was not sorry that the big, county family functions had to be postponed indefinitely. I am a quiet person, and I best enjoy my happiness when there is no one to look on. A selfish att.i.tude perhaps, but I try to pay my debts to humanity in other ways. Generally Betty sees to it that I do so.

In February "Thane Court" was sold at auction, and I bought it in. The property marched with that of the "Hundred," and being so well rid of one objectionable neighbor I had no mind to run any chances. Moreover, the land was of excellent quality, impoverished, it is true, by want of care and scientific cropping, but still capable of revival under reasonable management. I had bid it in for a price far under its real value, and I could easily get a tenant in case I concluded not to farm it myself. The house was old and in poor condition, and I determined to pull it down in the spring.

But I was spared the trouble, for one windy night in March I was awakened by the light pressure of Betty's hand on my shoulder. "There is a big fire over in the west," she said excitedly, "and I think it must be 'Thane Court.'"

I scrambled into some clothes, summoned all the men within reach, and made the best of my way to the scene of the conflagration, rather more than a mile distant.

Betty was right. "Thane Court" was on fire, and it was evident, at a glance, that the house was doomed. Buckets and handpumps were useless, and long before the fire apparatus from Calverton could cover the ten miles of rutted, frozen roads the edifice had been reduced to a smoking ruin.

It was three or four days later before we could venture to explore the smouldering debris. The furniture and other interior fittings were old and of no great value; all, of course, had been totally destroyed. The only thing left intact was a small safe, which I was informed, had stood in the room used by the elder Thaneford as an office. Now John Thaneford had not appeared at the sale, nor had he taken any steps to protect what interests he still retained in the estate. Everything in and about "Thane Court" had become my legal property, and so I had no hesitation in ordering the safe taken over to the "Hundred," it being my intention to open it and examine the contents. Of course any personal property would belong to John Thaneford, and I was quite sure of my own good faith in the matter. It might be impossible to locate the missing owner for some time to come, but we could cross that bridge when we came to it.

The safe was of comparatively modern workmanship, and seemed to have suffered no damage from its ordeal by fire. It was equipped with the usual numbered dial lock, and, naturally, I did not possess the combination. I could have sent for a safe expert from Baltimore, but the expense would have been considerable. Or mechanics from Calverton could have forced an opening by means of the oxygen flame, but so violent a procedure would have destroyed the safe itself, and I was not quite certain that I had the right to take such drastic action. True, John Thaneford had abandoned his property, and everything had been sold without reserve; nevertheless, I wanted to be sure of my ground before going further.

The safe had been thoroughly cleansed, and now stood temporarily under the princ.i.p.al staircase. I never pa.s.sed it without an inquiring glance; somehow Betty and I could not resist the temptation of speculating about it; we were as curious as children, ever intent upon discovering what secrets it might hold. But how to find the key to the mystery?

And then one evening Betty had a brilliant idea. "Do you remember," she asked, "a series of numbers that I got from Mr. Thaneford the day he died?"

"Of course." I pulled out my note-book, and read the formula aloud: "1-4-2-4-8."

"He certainly wanted to tell me something," persisted Betty. "Why shouldn't it have been the very combination we are looking for?"

"Easy enough to find out," I answered. I went over to the safe, knelt down and took hold of the k.n.o.b. Betty stood at my elbow, the note-book in her hand. "Ready?" she asked. "The numbers are: 1-4-2-4-8."

I turned the k.n.o.b, counting the clicks as they pa.s.sed. The door yielded and swung open.

Not much of a find after all--nothing but a leather-bound book resembling a diary in appearance. One of the covers had been slightly scorched by the intense heat, but the MS. seemed to be in excellent condition. I opened the book, scanned two or three lines, and looked up at Betty, who was leaning over my shoulder.

"Why it's just a jumble of letters!" she exclaimed in poignant disappointment. "I can't read a word of it; what does it mean?"

"Undoubtedly written in cypher," I replied. We looked at one another and laughed. Here indeed was an anti-climax.

Chapter XIII

_Le Chiffre Indechiffrable_

During the world war I had been on duty in the intelligence department, and I had taken much interest in the science of cryptography, although not connected personally with the handling of cypher despatches. I could therefore explain to Betty that cypher systems fall under four general heads.

1. The giving to words, or groups of letters, a purely arbitrary significance.

2. The use of mechanical transformers in the shape of a screen or grid.

3. The subst.i.tution of numbers or other symbols for the original characters.

4. The transposition of letters according to a constant formula.

"Obviously," I began, "the example before our eyes--long lines of letters without breaks or marks of punctuation--does not come under the first heading. It contains no recognizable words, or phonetic groups, which might correspond in the code book to actual sentences. For example, in the ordinary commercial systems, the word _Barbarian_ may mean: 'The wheat market is advancing.' But if I cable the word _Civilisation_ I really intend to say: 'Australian wool crop is a failure.' The princ.i.p.al value of the elaborate code system is in the saving of cable tolls, a single word conveying the meaning of an entire sentence. It is necessary, of course, that all of the correspondents should possess individual copies of the code, and loss or theft of the book discloses the whole secret. Do you understand?"

Betty thought she did, and seemed so interested that I was emboldened to a.s.sume my best lecture manner.

"Under the second head we may consider the mechanical device known as the grid, grille, or screen.

"The instrument in question consists of a plate, usually made of metal, pierced by a number of holes of different sizes and irregularly s.p.a.ced.

When the writer sets out to prepare his message he lays the grid on the paper, and marks in the letters making up the words of his despatch through the apertures. Then the screen is removed, and the blank s.p.a.ces are filled up with writing which has nothing to do with the real subject matter, the process being repeated until the entire message has been coded. The recipient is provided with a precisely similar grid. By applying it to the communication he is then able to read, through the holes, the text of the secret message. The ancient Romans used a variation of this method, somewhat as follows. A long strip of paper was wound spirally about a cylinder or cone; the writing was then done parallel with the axis of the metal form. When unrolled, the communication seemed to be made up of arbitrary signs really parts of letters which were entirely unintelligible. The recipient, however, by rewinding the strip on a precisely similar form, would be able to read the message.

"Of course we may rule out the mechanical device. In this case we have a long communication of several hundred words, and the grille would be impracticable--too wasteful of s.p.a.ce."

"That disposes of No. 2," said Betty hopefully. "What next?"

"In cla.s.s 3 the coded message consists of numbers, or even of pure symbols--stars and daggers or what not. The latter variation is generally pure subst.i.tution, and may be called kindergarten cryptology.

No one but a rank amateur would employ such a system.

"In the numeral code each correspondent is supplied with a dictionary, the same edition of course. Each word of the original message is represented by a group of five numbers, two designating the location of the required word on the page, and the remaining three denoting the number of the page itself. The process, both of coding and of uncoding, is very laborious, and hardly pays for the trouble involved. Another way to use the two dictionaries is to interpret the words of the code message by subst.i.tuting other words removed a certain definite distance up or down the column. Suppose it is agreed that 'fifteen down' shall be the key, and that the despatch, as received, reads: _Bull Collier_. The recipient takes his copy of the dictionary, looks up the word _Bull_, and counts down fifteen, getting the word _Buy_. Similarly, _Collier_ gives him _Copper_, and the decoded message will mean: 'Buy copper.'

Finally, we may use a predetermined series of numbers as a key formula.

We then divide the message to be coded into the same number of letter groups, and work out an intricate transposition, reversing the process in order to decode."

"Rather makes your head ache," remarked Betty plaintively. "Besides, this cypher doesn't use numbers at all."

"Right you are," I acquiesced, "and we are undoubtedly dealing with a system of the fourth order in which the letters are transposed according to a constant prearranged formula.

"Let us first consider the simple form; the regular subst.i.tution of one letter of the alphabet for another. For example, X always takes the place of E, while B invariably means T, and so on. Such cyphers are easily read by the expert, who works on the principle that all the letters of the English alphabet may be ranked on a numerical scale of average frequency in use. The letter E heads the list; consequently, if any particular symbol predominates in the message it must correspond to that hard-worked vowel. Again, as _the_ is the commonest word group in the language we are quickly able to identify what stands for T and H.

But this is quite too transparent a code for serious use."

"Then don't waste time over it," said my practical-minded wife. "Old Mr.

Thaneford was not a foolish person."

I took a long look at the incomprehensible jumble of letters.

"There are any number of formulae," I went on, "by means of which we may effect a transposition of letters, the subst.i.tution being variable or irregular. For instance, the 'Checkerboard,' invented by the Russian nihilists, and similar devices, most of which depend for secrecy upon single or double key-words. Perhaps the cleverest system in this group is the cypher called by the French, 'Le Chiffre Indechiffrable.'"

"'The Undecypherable Cypher,'" commented Betty. "Sounds rather hopeless."

"Well, you can decide for yourself if there is any reasonable possibility of unravelling it, unless you are lucky enough to stumble on the key-word."