four
o'clock
The boat was a good-sized one , and when not under sail was generally rowed by two strong negroes accustomed to the work . Sometimes for half an hour at a time Vincent ceased rowing , and let the boat drift along quietly . There was no hurry , for he had a day and two nights to get down to the mouth of the river , a distance of some seventy miles , and out to sea , far enough to intercept the vessel . At four o'clock they arrived at Cumberland , where the Pamunky and Mattapony Rivers unite and form the York River . Here they were in tidal waters ; and as the tide , though not strong , was flowing up , Vincent tied the boat to the branch of a tree , and lay down in the bottom for an hour 's sleep , telling Dan to wake him when the tide turned , or if he heard any noise . Day had broken when the boat drifted round , and Dan aroused him . The boat was rowed off to the middle of the river , as there could be no longer any attempt at concealment .