midnight
The night was spent with the ship floating on the surface of the ocean , only enough speed being kept up to give her steerage way . The professor did not want to go below the waves until he had repaired the switch board . Watch was kept , for , though they were out of the regular line of ocean travel , there was no telling when a vessel might come along and run them down , for the _ Porpoise _ did not show above the waves more than a few feet , and carried no lights . Mark had the watch just after midnight , and was sitting in the conning tower , the door of which opened out on the small deck . He had swept the surface of the water with powerful glasses and was sure there were no ships in sight . So , feeling that he would like to stretch his legs , he walked up and down on the platform . He had reached the after end , and was about to turn and go back , when he was startled to see between him and the conning tower a white object .