She gave him the letter, and after a long, tender farewell, he took his departure. Going straight to his room at Mrs. Quinlan’s, he lighted the lamp, so that if Emily chanced to look over the way, she would fancy him at work upon the cryptogram. Morrow waited until the little house opposite was plunged in darkness; then very stealthily he crept down the stairs and let himself out, the precious letter carefully tucked into an inside pocket.

Morrow proceeded at once to Blaine’s office and found his chief awaiting him.

“Here’s the letter, sir,” he announced, as he placed the single sheet of paper on the desk before the detective. “I can’t make anything out of it, but you probably will. It’s curious, isn’t it! Why, for instance, are those little dots placed near some of the crazy figures, and not others?”

Blaine picked the letter up, and examined it with eager interest.

“It’s comparatively simple,” he remarked, as he spread it flat upon the desk, and taking up pen and paper, copied it rapidly. “Symbolic cryptograms are usually decipherable, with the expenditure of a little time and effort. There is a method which is universally followed, and has been for ages. For instance, the letter e is recognized as being the most frequently used, in ordinary English, of the whole alphabet; after that the vowels and consonants in an accepted rotation which I will not take up our valuable time in discussing 168 with you now, since we will not even need to use it, in this case.––Here, take this copy, and see if you can follow me.”

He passed the sheet of paper across to his operative and Morrow gazed again upon the curiously shaped characters which from close scrutiny had become familiar, yet still remained maddeningly baffling to him:

“Now,” resumed Blaine, “presupposing that in an ostensibly friendly message beginning with a word of four letters, that word is dear, and we’ve two important vowels to start with. We know the letter was addressed to Brunell, from an old partner in crime. We will assume, therefore, that the two words of three letters each, following dear are either old Jim, old man, or old boy. Let us see how it works out.”

The detective scribbled hastily on a pad for several minutes, then leaned back in his chair, with a sigh of satisfaction.