four o'clock
`` Now , Jacob , if you have a mind to turn in . I 'm not sleepy -- you shall keep the morning watch . '' `` No , Tom , you 'd better sleep first . I 'll call you at four o'clock . We ca n't weigh till tide serves ; and I shall have plenty of sleep before that . '' Tom went to bed , and I walked the deck till the morning , thinking over the events of the day , and wondering what the Dominie would say when he came to his senses . At four o'clock , as agreed , I roused Tom out , and turned into his bed , and was soon as fast asleep as old Tom and the Dominie , whose responsive snores had rung in my ears during the whole time that I had walked the deck .