“Why, it’s just this. Wherever number one came we put the letter a. If number thirteen appeared we’d substitute the thirteenth letter in the alphabet in its place.”
“Which would be m,” said George after a little calculation on his fingers.
“That’s right,” exclaimed Grant. “Now do you see how it was done?”
“Of course. Isn’t that simple?”
“It took us long enough to find it out though,” said John.
“Well, I should say so,” exclaimed George. “Weren’t we stupid?”
“I don’t know,” said Grant. “The simplest things are often the hardest to explain. Of course when you get the key the rest is easy enough.”
“According to this code then,” said Fred, “one, two, three would be a, b, c. Is that right?”
“Yes,” said Grant, “and twenty-four, twenty-five and twenty-six would be x, y, z.”
“I see,” exclaimed Fred. “You couldn’t have a number higher than twenty-six in this code then, could you?”