half past eleven
Meanwhile , what of Frank and the submarine ? Shaping his course by the chart which Captain Jack had given him , Frank kept the course accurately . The speed of the vessel was maintained at five knots , in accordance with Captain Jack 's calculations . As Frank 's watch showed half past eleven , he felt that the time to exercise the greatest caution had come . The lad turned the wheel over to Williams and took the latter 's place at the periscope . Directly he was able to make out the coast line , and even at this distance he felt certain that he could make out a long row of buildings in the background . The submarine was , of course , still too far away for possible vessels , which would lie low on the water , to be within the lad 's range of vision .