I found it as I had left it in the morning. Indeed, without using a lever, as I had done, no one could have opened it. I drew back the curtains of the upper berth so that I could see well into it. By the captain's advice I lighted my reading-lantern, and placed it so that it shone upon the white sheets above. He insisted upon sitting on the portmanteau, declaring that he wished to be able to swear that he had sat before the door.
Then he requested me to search the state-room thoroughly, an operation very soon accomplished, as it consisted merely in looking beneath the lower berth and under the couch below the porthole. The spaces were quite empty.
"It is impossible for any human being to get in," I said, "or for any human being to open the port."
"Very good," said the captain, calmly. "If we see anything now, it must be either imagination or something supernatural."
I sat down on the edge of the lower berth.
"The first time it happened," said the captain, crossing his legs and leaning back against the door, "was in March. The passenger who slept here, in the upper berth, turned out to have been a lunatic—at all events, he was known to have been a little touched, and he had taken his passage without the knowledge of his friends. He rushed out in the middle of the night, and threw himself overboard, before the officer who had the watch could stop him. We stopped and lowered a boat; it was a quiet night, just before that heavy weather came on; but we could not find him. Of course his suicide was afterwards accounted for on the ground of his insanity."
"I suppose that often happens?" I remarked, rather absently.
"Not often—no," said the captain; "never before in my experience, though I have heard of it happening on board of other ships. Well, as I was saying, that occurred in March. On the very next trip—What are you looking at?" he asked, stopping suddenly in his narration.
I believe I gave no answer. My eyes were riveted upon the porthole. It seemed to me that the brass loop-nut was beginning to turn very slowly upon the screw—so slowly, however, that I was not sure it moved at all. I watched it intently, fixing its position in my mind, and trying to ascertain whether it changed. Seeing where I was looking, the captain looked too.
"It moves!" he exclaimed, in a tone of conviction. "No, it does not," he added, after a minute.