“No! You’re jesting,” I answered, convinced, at the same time, that he was in earnest.
“I’ll soon show you,” was his exultant response.
“How was it you struck the key?”
“That is hard to tell, more than you can explain how it is, after you have puzzled your brain for a long time over an arithmetical problem, it suddenly becomes clear to you.”
He sat down by my desk.
“I figured and studied, and tried those letters every way I could think of until midnight, and was on the point of going to bed, when the whole thing flashed upon me. You know, Mr. Melville, that in trying to unravel a cipher, the first thing necessary is to find the key-word, for it must be there somewhere; and if you look sharp enough it will reveal itself. One single letter gave it to me.”
“How was that?”
“If you will look at the telegram,” said Ben, spreading it out before me, “you will notice that in one instance only is a single letter seen standing by itself. That is the letter ‘b,’ which I concluded must stand for the article ‘a,’ for I know of no other, unless it is ‘I.’ Now, the letter ‘b’ is the second one in the alphabet, and stands next in order to ‘a.’ If this system is followed throughout the cipher, we have only to take, instead of the letters as written, the next in order as they occur in the alphabet. But when I tried it on the following word, it failed entirely. Luckily I tested the second in the same manner, and I was surprised to find it made a perfect word, viz.: ‘chance.’ The third came to naught, but the fourth developed into ‘your.’ That proved that every other word of the message was constructed in this manner, and it did not take me long to bring them out into good English. This was a big help, I can tell you, and it was not long before I discovered that in the alternate words the system reversed; that is, instead of taking the letter immediately succeeding, the writer had used that which immediately precedes it in the alphabet. Applying this key to the telegram, it read thus:
“‘Must wait till fall; Sam has a better chance south. Your bank will keep.’”
“Now,” added Ben, who was warranted in feeling jubilant over his success, “that is a very ordinary cipher—one which hundreds would make out without trouble. Had the writer run his letters all together—that is, without any break between the words—I would have been stumped. Besides, he uses no blind words, as he ought to have done; and it looks very much as if he calls everything by its right name, something which I should think no person anxious to keep such a secret would do. If he means ‘bank,’ he might as well have called it by another name altogether.”