Grant’s companions sat and looked at him in amazement not unmixed with alarm. They could see no reason for his strange behavior and were at a complete loss what to make of it. They watched their comrade execute a war dance around the entrance to the cave for some moments and finally disappear within, uttering one last triumphant whoop.

“What struck him?” exclaimed John in perplexity.

“He’s gone crazy I guess,” said Fred. “I can’t think of anything else.”

“Ah believe yo’ am right,” said Sam in a hollow voice. “Ef he try to mess me up Ah sho’ gwine use dis knife.”

“Put that away, Sam,” said John, sharply. “Don’t be silly.”

“But ef he’s crazy,” protested Sam, “Ah suttinly boun’ proteck mahself.”

“He’s not crazy,” exclaimed George. “He’ll be out in a minute and tell us just what is wrong with him.”

“Go and see what he’s doing, Pop,” urged Fred.

“I will not. He said he’d got it and he might get me, too. What do you suppose he was talking about anyway?”

“Here he comes now. Ask him.”

Grant emerged from the cave, his manner showing how excited he was. He walked rapidly and his hands shook with nervousness. He carried the piece of parchment that had become so familiar to the four boys.

“He must have meant the code,” whispered Fred to George.

“He couldn’t have solved it,” said George in a low voice. “How could he?”

“I don’t know. At any rate he may have had an idea.”

Grant advanced rapidly towards the spot where his companions were grouped and seated himself in front of them.

“What’s going on, Grant?” demanded John curiously.

“Just a minute and I’ll show you something,” and he spread the code out on the ground while the rest of the little party peered eagerly over his shoulder.

“Now, first of all,” began Grant, “you all know what this is.”

“It’s a combination to a safe,” said George readily.

“Keep quiet, Pop,” exclaimed Fred. “Give him a chance.”

“It’s a code,” said Grant, ignoring George’s facetious remark.

“We know that,” agreed Fred. “Don’t be so mysterious.”

“What’s the highest number in it?” demanded Grant.

“He sounds like a trick man,” laughed George jeeringly.

“No treasure for Pop,” said Grant shortly. “What’s the highest number in it?”

“I guess we’ll have to do it this way,” said John with a sigh. “Let me see,” he added. “I guess twenty-five is the highest number.”

“All right. How many letters are there in the alphabet?”

“Twenty-six.”

“But, Grant,” Fred protested, “I don’t see what you’re getting at?”

“You will soon enough. Just have a little patience.”

“But why don’t you tell us what your idea is right now?”

“Because I don’t want to. At any rate it’s only an idea and I don’t know whether it’s right or not and I haven’t worked it out myself. That’s what we are doing now and I want you all to help me. The whole thing may be wrong, but it sounds pretty good to me. John’s remark about the number of letters in the alphabet gave me the idea.”

“Then I ought to get the credit if we solve the code,” exclaimed John.

“You’ll be lucky if you don’t get shot,” said George. “You ought to be.”

“Go ahead with your explanation, Grant,” urged Fred. “Everybody keep quiet and give him a chance.”

“All right,” said Grant. “We’ve noticed that the highest number is twenty-five and that there are twenty-six letters in the alphabet, haven’t we?”

“We have,” said John so solemnly that George giggled outright. His friends, however, were in a very serious mood and he quickly realized that his hilarity was decidedly out of place.

“What number appears most frequently?”

“I guess fourteen does,” said Fred after a hasty survey of the figures spread out on the ground before them.

“No, five,” exclaimed John. “There are a good many more fives than there are fourteens.”

“Perhaps there are,” Fred admitted. “Go ahead, Grant.”

Grant made some calculations that his comrades could not follow before he replied to Fred’s remark. His friends eyed him curiously.

“Suppose we put the letter e wherever the number five occurs,” he said at length.

“What are you going to do that for?” demanded George, now very much interested in the experiment Grant was conducting.

“Never mind why,” exclaimed Grant. “Do as I say.”

“Give me a sheet out of your diary, Pop,” said Fred. “I’ll do the figuring.”

“Are you going to write it all down?” inquired George.

“Shall I, Grant?”

“Put it all down. We’ll go slowly, but we’ll do it right.”

“All right,” exclaimed Fred. “Here goes,” and he wrote as follows, substituting the letter for the number every time he came to it:

20 - 1 - 11 - e - 1 - 3 - 15 - 21 - 18 - 19 - e - 4 - 21 - e - 14 - 15 - 18 - 20 - 8 - 15 - 14 - e - 8 - 21 - 14 - 18 - e - 4 - 6 - e - e - 20 - 6 - 18 - 15 - 13 - 20 - 8 - e - 19 - 15 - 21 - 20 - 8 - e - 18 - 14 - e - 24 - 20 - 18 - e - 13 - 9 - 20 - 25 - 15 - 6 - 19 - 8 - 1 - 18 - 11 - 18 - 15 - 3 - 11 - 20 - 8 - e - 14 - e - 1 - 19 - 20 - 6 - 9 - 6 - e - e - 20 - 1 - 14 - 4 - 14 - 15 - 18 - 20 - 8 - 2 - 25 - e - 1 - 19 - 20 - 20 - 8 - 9 - 18 - 20 - 25 - 20 - 8 - 18 - e - e - 4 - 9 - 7.

“Well,” exclaimed George when Fred had finished, “it may be very simple and all that, but it doesn’t mean anything to me.”

“Of course, not yet,” said Grant. “Have a little patience.”

“Why don’t you tell us what your system is?”

“No, you wait.”

“How about fourteen now?” demanded Fred. “We decided that was a pretty common number, you know. What shall I do with that?”

“I’ll tell you,” said Grant and once again he appeared to calculate something in his head. “In place of fourteen put the letter n,” he directed, “and use the copy you just made.”

“What do you mean by the copy I just made?”

“I mean leave the letter e where you put it in the last time.”

“Here we go,” exclaimed Fred and this is what he wrote:

20 - 1 - 11 - e - 1 - 3 - 15 - 21 - 18 - 19 - e - 4 - 21 - e - n - 15 - 18 - 20 - 8 - 15 - n - e - 8 - 21 - n - 4 - 18 - e - 4 - 6 - e - e - 20 - 6 - 18 - 15 - 13 - 20 - 8 - e - 19 - 15 - 21 - 20 - 8 - e - 18 - n - e - 24 - 20 - 18 - e - 13 - 9 - 20 - 25 - 15 - 6 - 19 - 8 - l - 18 - 11 - 18 - 15 - 3 - 11 - 20 - 8 - e - n - e - 1 - 19 - 20 - 6 - 9 - 6 - 20 - 25 - 6 - e - e - 20 - 1 - n - 4 - n - 15 - 18 - 20 - 8 - 2 - 25 - e - 1 - 19 - 20 - 20 - 8 - 9 - 18 - 20 - 25 - 20 - 8 - 18 - e - e - 4 - 9 - 7.

“Clear as mud,” cried George, slapping Fred heartily on the back. “You’re a wonder, Peewee, my boy.”

“I must confess I don’t understand all this business,” exclaimed Fred. “Why don’t you tell us what you are trying to do, Grant?”

“Because I’m not sure that I know myself.”

“Tell us what you think anyway,” urged John. “There’s no harm in that.”

“I’d rather not,” said Grant. “If you fellows don’t want to help me any more though, I’m perfectly willing to work it out by myself.”

“No, you don’t,” exclaimed Fred. “If there’s anything going to happen around here I want to be on hand.”

“An’ me too,” said Sam eagerly. “Ah wants to be heah when dat treasah am discovahed. Ah’ll fix dem niggers in Richmond yet.”

“Good boy, Sam,” exclaimed Grant. “You and I will work it out together.”

“Ah cain’t read nor write,” said Sam disconsolately. “Ah’s afraid Ah wouldn’t be ob bery much help to yo’. Ah can suttingly do some diggin’ dough.”

“Oh, I’m going to stay along; don’t worry about that,” said Fred. “I wish Grant would tell us what he’s trying to do, but I’m going to stay by him whether he tells or not.”

“I know what he’s trying to do,” said George. “It’s simple enough.”

“What is it then?” demanded Grant.

“Why, he thinks these numbers are used in place of letters. A certain number means a certain letter and wherever he sees it he substitutes the letter.”

“We all know that much,” cried John scornfully. “What we want to know is how he figures out what letter to put in place of a certain number. Can you tell us that?”

“No, I can’t,” George admitted ruefully.

“Then you don’t know how he does it, do you?”

“No, I don’t. That is, not yet.”

“Go ahead then, Grant,” exclaimed John. “We’re wasting time here.”

“You want to go on with it, do you?”

“Of course we do.”

Grant picked up the code and studied it attentively for some moments. Finally he put it down again. “Suppose we put the letter h in place of the figure eight,” he said. “Eight seems to be a fairly common number.”

Once again Fred copied the mysterious set of numbers, making the change that Grant had suggested.