Sentence:  Long after his cigar burnt bitter, he sat with eyes fixed on the blaze. When the flames at last began to flicker and <WSD>subside</WSD>, his lids fluttered, then drooped ; but he had lost all reckoning of time when he opened them again to find Miss Erroll in furs and ball-gown kneeling on the hearth and heaping kindling on the coals,nb.... 
Meaning of the word marked with <WSD> tags:  To fall into a state of calm; to be calm again; to settle down; to become tranquil; to abate.