eight o'clock
Between nightmare after nightmare he had heard all the horrors of the night sound out in the darkness and the glimmering dawn . Then he had fallen into a heavy sleep , which had left him on awaking broken with fatigue . He had given himself a cold douche , and this had calmed his nerves ; then he had dressed quickly . When eight o'clock struck he was at his writing-table , thinking things over : `` It 's no laughing matter . I thought at first that the Dollon affair was quite ordinary ; but I am mistaken . The warning I received last night leaves me no doubts on that head . Since the guilty person thinks it necessary to ask me to keep quiet , it is evident he fears my intervention ; if he is afraid of that it is because it must be hurtful to him ; if disastrous to him , a criminal , it is evident that it must be useful to honest folk .