“Great!” interrupted Sally, enthusiastically, who had seen the method even quicker than Miss Camilla. “But suppose it worked the other way, reading the side line first? Then ‘T’ would be ‘15.’ ”

“Of course, that’s true,” admitted Doris. “I suppose there must have been some understanding between those who invented this code about which line to read first. The only way we can discover it is to puzzle it out both ways, and see which makes sense. One will and the other won’t.”

It all seemed as simple as rolling off a log, now that Doris had discovered the explanation. Even Miss Camilla was impressed with the value of the discovery.

“But what is the meaning of these plus and minus signs?” she queried. “I suppose they stand for something.”

“I think that’s easy,” answered Doris. “In looking over it, I see there are a great many more plus than minus signs. Now, I think the plus signs must be intended to divide the numbers in groups of two, so that each group stands for a letter. Otherwise they’d be all hopelessly mixed up. And the minus signs divide the words. And every once in a while, if you notice, there’s a multiplication sign. I imagine those as the periods at the end of sentences.”

They all sat silent a moment after this, marveling at the simplicity of it. But at length Doris suggested:

“Suppose we try to puzzle out a little of it and see if we are really on the right track? Have you a piece of paper and a pencil, Miss Camilla?” Miss Camilla went indoors and brought them out, quivering with the excitement of the new discovery.

“Now, let’s see,” began Doris. “Suppose we try reading the top line first. ‘56’ would be ‘1’ and ‘14’ would be ‘2.’ Now ‘12’ may mean a word or it may not. It hardly seems as if a note would begin with that. Let’s try it the other way. Side line first. Then ‘56’ is ‘m,’ and ‘14’ is ‘y.’ ‘My’ is a word, anyway, so perhaps we’re on the right track. Let’s go on.”

From the next series of letters she spelled the word “beloved” and after that “sister.” It was plain beyond all doubting that at last they had stumbled on a wonderful discovery.

But she got no further than the words, “my beloved sister,” for, no sooner had Miss Camilla taken in their meaning than she huddled back in her chair and, very quietly, fainted away.