a note of it. I now looked over the papers to see if I could find traces of any of the methods with which I was acquainted; before long I had an idea.
It was only a rudimentary idea, a surmise, a possibility; but still it was worth going into. It was not any cause of undue pride to me, for it came as a corollary to an established conclusion, rather than as a fine piece of reasoning from acute observation. The dates of the letters gave the period as the end of the sixteenth century, when one of the best ciphers of that time had been conceived, the "Biliteral Cipher" of Francis Bacon. To this my attention had been directed by the work of John Wilkins and I had followed it out with great care. As I was familiar with the principle and method of this cipher I was able to detect signs of its existence; and this being so, I had at once strong hopes of being able to find the key to it. The Biliteral cipher has as its great advantage, that it can be used in any ordinary writing, and that its forms and methods are simply endless. All that it requires in the first instance is that there be some method arranged on between the writer and the reader of distinguishing between different forms of the same letter. In my desk I had a typewritten copy of a monograph on the subject of the Biliteral cipher, in which I half suggested that possibly Bacon's idea might be worked out more fully so that a fewer number of symbols than his five would be sufficient. Leaving my present occupation for a moment I went and got it; for by reading it over I might get some clue to aid me. Some thought which had already come to me, or some conclusion at which I had already arrived might guide me in this new labyrinth of figures, words and symbols.[1]
When I had carefully read the paper, occasionally referring to the documents before me, I sat down and
- ↑ See Appendix A.
