"Nor can I," he answered, "and yet I have spent nights and nights of my life in signal-boxes and never was the least bit drowsy; perhaps it's the cold."
"Perhaps it is," I said; "but I have been out on as freezing nights before, and——"
The man did not reply; he had sat down again; his head was nodding.
I was just about to go up to him and shake him, when it suddenly occurred to me that I might as well let him have his sleep out. I soon heard him snoring, and he presently fell forward in a heap on the floor. By dint of walking up and down, I managed to keep from dropping off myself, and in torture which I shall never be able to describe, the night wore itself away. At last, towards morning, I awoke Henderson.
"You have had a good nap," I said; "but never mind, I have been on guard and nothing has occurred."
"Good God! have I been asleep?" cried the man.
"Sound," I answered.
"Well, I never felt anything like it," he replied. "Don't you find the air very close, sir?"
"No," I said; "it is as fresh as possible; it must be the cold."
"I'll just go and have a look at the light at the tunnel," said the man; "it will rouse me."