It was about a foot long and perhaps four inches wide. Through it ran a piece of paper which unrolled from one coil and wound up on another, actuated by clockwork. Across the blank white paper ran an ink line traced by a stylographic pen, such as I had seen in mechanical pencils used in offices, hotels, banks and such places.
Kennedy examined the thing with interest.
"What is it?" I asked.
"A new seismograph," he replied, still gazing carefully at the rolled up part of the paper. "I have installed it because it registers every footstep on the floor of our apartment. We can't be too careful with this Clutching Hand. I want to know whether we have any visitors or not in our absence. This straight line indicates that we have not. Wait a moment."
Craig hastily unlocked the door and entered. Inside, I could see him pacing up and down our modest quarters.
"Do you see anything, Walter?" he called.
I looked at the seismograph. The pen had started to trace its line, no longer even and straight, but zigzag, at different heights across the paper.
He came to the door. "What do you think of it?" he inquired.
"Splendid idea," I answered enthusiastically.
Our apartment was, as I have said, modest, consisting of a large living room, two bedrooms, and bath—an attractive but not ornate place, which we found very cosy and comfortable. On one side of the room was a big fire place, before which stood a fire screen. We had collected easy chairs and capacious tables and desks. Books were scattered about, literally overflowing from the crowded shelves. On the walls were our favorite pictures, while for ornament, I suppose I might mention my typewriter and now and then some of Craig's wonderful scientific apparatus as satisfying our limited desire for the purely aesthetic.