The Ear in the Wall

by Arthur B. Reeve

It was early the following morning that I missed Kennedy from our apartment. Naturally I guessed from my previous experiences with that gentleman that he would most likely be found at his laboratory, and I did not worry, but put the finishing touches on a special article for the Star which I had promised for that day and had already nearly completed.

Consequently it was not until the forenoon that I sauntered around to the Chemistry Building. Precisely as I had expected, I found Kennedy there at work.

I had been there scarcely a quarter of an hour when the door opened and Clare Kendall entered with a cheery greeting. It was evident that she had something to report.

"The letter to Betty Blackwell which you sent to the Montmartre has come back, unopened," she announced, taking from her handbag a letter stamped with the post-office form indicating that the addressee could not be found and that the letter was returned to the sender. The stamped hand of the post-office pointed to the upper left-hand corner where Clare had written in a fictitious name and used an address to which she frequently had mail sent when she wanted it secret.

"Only on the back," she pursued, turning the letter over, "there are some queer smudges. What are they? They don't look like dirt."

Kennedy glanced at it only casually, as if he had fully expected the incident to turn out as it did.

"Not unopened, Miss Kendall," he commented. "We have already had a little scientific letter-opening. This was a case of scientific letter-sealing. That was a specially prepared envelope."

He reached down into his desk and pulled out another, sealed it carefully, dried it, then held it over a steaming pan of water until the gum was softened and it could be opened again. On the back were smudges just like those on the letter that had been returned.

"On the thin line of gum on the flap of the envelope," he explained, "I have placed first a coating of tannin, over which is the gum. Then on the part of the envelope to which the flap adheres when it is sealed I placed some iron sulphate. When I sealed the envelope so carefully I brought the two together separated only by the thin film of gum. Now when steam is applied to soften the gum, the usual method of the letter-opener, the tannin and the sulphate are brought together. They run and leave these blots or dark smudges. So, you see, someone has been found at the Montmartre, even if it is not Betty Blackwell herself, who has interest enough in the case to open a letter to her before handing it back to the postman. That shows us that we are on the right trail at least, even if it does not tell us who is at the end of the trail. Here's another thing; This 'Marie' is a new one. We must find out about her."

"At the Futurist Tea Room at four this afternoon, when she meets our good friend, young Dr. Harris," reminded Clare. "Between cabarets and tea rooms I don't know whether this is work or play."