“She thinks you are not well.  She asks you to have that prescription filled again.”

“Tell her I will do it to-morrow morning.  Is there anything else?”

Rap! rap! came back faintly: 

“John, John, don’t go yet,” pleaded the old man earnestly.  It was easy to see how thoroughly he believed in “John,” as perhaps well he might after the warning of his wife’s death three nights before.  “Won’t you answer one other question?”

Fainter, almost imperceptibly, came a rap! rap!

For several minutes the old man sat absorbed in thought, trance-like.  Then, gradually, he seemed to realise that we were in the room with him.  With difficulty he took up the thread of the conversation where the rappings had broken it.

“We were talking about the photographs,” he said slowly.  “I hope soon to get one of my wife as she is now that she is transfigured.  John has promised me one soon.”

He was gathering up his treasures preparatory to putting them back in their places of safekeeping.  The moment he was out of the room Craig darted into the cabinet and replaced his mechanism in the box.  Then he began softly to tap the walls.  At last he found the side that gave a noise similar to that which we had heard, and he seemed pleased to have found it, for he hastily sketched on an old envelope a plan of that part of the house, noting on it the location of the side of the cabinet.

Kennedy almost dragged me back to our apartment, he was in such a hurry to examine the apparatus at his leisure.  He turned on all the lights, took the thing out of its case, and stripped off the two sheets of ruled paper wound around the two revolving drums.  He laid them flat on the table and studied them for some minutes with evidently growing satisfaction.

At last he turned to me and said, “Walter, here is a ghost caught in the act.”

I looked dubiously at the irregular up-and-down scrawl on the paper, while he rang up the Homicide Bureau of the Central Office and left word for O’Connor to call him up the first thing in the morning.

Still eyeing with satisfaction the record traced on the sheets of paper, he lighted a cigarette in a matter-of-fact way and added:  “It proves to be a very much flesh-and-blood ghost, this ‘John.’  It walked up to the wall back of that cabinet, rapped, listened to old Vandam, rapped some more, got the answer it wanted, and walked deliberately away.  The cabinet, as you may have noticed, is in a corner of the room with one side along the hallway.  The ghost must have been in the hall.”

“But who was it?”

“Not so fast, Walter,” laughed Craig.  “Isn’t it enough for one night that we have found out that much?”

Fortunately I was tired, or I certainly should have dreamed of rappings and of “John” that night.  I was awakened early by Kennedy talking with someone over the telephone.  It was Inspector O’Connor.