Sentence:  There I lay on one side with a thin and rotten plank between the dead man and me, dazed with the blow to my head, and breathing hard; while the glow of torches as they came down the passage reddened and <WSD>flickered</WSD> on the roof above. 
Meaning of the word marked with <WSD> tags:  To keep going on and off; to appear and disappear for short moments; to flutter.