sh, the ground trembled, a
few sparks from the engine whirled up into the darkness, and the train
plunged into the tunnel.

"And now," said Henderson, as he pushed back the levers, "not another
train till daylight. My word, it is cold!"

It was intensely so. I piled some more wood on the fire and, turning up
the collar of my heavy ulster, sat down at one end of the bench and
leant my back against the wall. Henderson did likewise; we were neither
of us inclined to speak. As a rule, whenever I have any night work to
do, I am never troubled with sleepiness, but on this occasion I felt
unaccountably drowsy. I soon perceived that Henderson was in the same
condition.

"Are you sleepy?" I asked of him.

"Dead with it, sir," was his answer; "but there's no fear, I won't drop
off."

I got up and went to the window of the box. I felt certain that if I sat
still any longer I should be in a sound sleep. This would never do.
Already it was becoming a matter of torture to keep my eyes open. I
began to pace up and down; I opened the door of the box and went out on
the little platform.

"What's the matter, sir?" inquired Henderson, jumping up with a start.

"I cannot keep awake," I said.

"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."

He went on to the little platform, whilst I bent over the fire and began
to build it up. Presentl