And a fascinating game it proved. The possibility that the queer paper in the iron box might contain directions for finding some hidden treasure made it all the more alluring.
"There are any number of ciphers," Allen explained, when several copies had been made of the original. "The simplest is to change the letters of the alphabet about, using Z for A, and so on. Another simple one is to make figures stand for letters, as No. 1 is A, and so on. But those are so simple that only a schoolboy would use them."
"What are same of the more difficult ciphers?" asked Betty.
"Well, there are so many I don't know that I could explain them all. But the most simple of the difficult ones is the taking of a number of arbitrary signs or symbols to represent the letters of the alphabet. That is what was done in Poe's 'Gold Bug,' you remember. Unless the person has a copy of the list of signs and symbols it is very difficult to decipher that cipher, or decode it, as they say in government circles."
"Ahem!" exclaimed Will, with an important air, as all eyes were turned on him. "I ought to know something about that, but you see they haven't trusted me with the code book yet. Now then, Allen, how are we to go about this Chinese puzzle?"
"If I had that story of Poe's here, it would be rather easier," Allen said. "As it is, we shall have to do a little preliminary work. To start off with we will take the letter E."
"Why E?" asked Roy.
"Because of all the letters in the ordinary use of English, that letter most frequently occurs," Allen answered. "In other words, if you take a written, or printed, page, and count up the letters, you will find that E is used most frequently."
"What is the next one?" asked Mollie. "Oh, isn't this fascinating, girls!"
"It will be more fascinating to discover the secret," Betty said.