Spreading the oiled paper on a table top made of clear glass, the Librarian turned on a battery of strong electric lights underneath so that any watermark or secret writing would have been at once apparent. But there was nothing on the sheet except line after line of meaningless letters.
"It's possible, of course, that there may be some writing in invisible ink on the sheet," admitted the cipher expert. "But the fact that oiled paper is used would seem to preclude that. The code itself may be any one of several varieties and it's a matter of trying 'em all until you hit upon the right one."
"I thought that Poe's story of 'The Gold Bug' claimed that any cipher could be read if you selected the letter that appeared most frequently and substituted for it the letter 'e,' which is used most often in English, and so on down the list," stated Barlow.
"So it did. But there are lots of things that Poe didn't know about codes." Thurber retorted, his eyes riveted to the sheet before him. "Besides, that was fiction and the author knew just how the code was constructed, while this is fact and we have to depend upon hard work and blind luck.
"There are any number of arbitrary systems which might have been used in writing this message," he continued. "The army clock code is one of them—the one in which a number is added to every letter figure, dependent upon the hour at which the message is written. But I don't think that applies in this case. The cipher doesn't look like it—though I'll have to admit that it doesn't look like any that I've come across before. Let's put it on the blackboard and study it from across the room. That often helps in concentrating."
"You're not going to write the whole thing on the board?" queried the operative.
"No, only the first fifteen letters or so," and Thurber put down this line:
I i i t f b b t t x o r q w s b b
"Translated into what we call 'letter figures,'" he went on, "that would be 9 9 9 20 6 2 2 20 20 24 15 18 17 23 19 2 2—the system where 'a' is denoted by 1, 'b' by 2, and so on. No, that's still meaningless. That repetition of the letter 'i' at the beginning of the message is what makes it particularly puzzling.
"If you don't mind, I'll lock the door and get to work on this in earnest. Where can I reach you by phone?"