 A stronger argument seems to be that ships coming from the north might line up the lights in order to determine when it was safe to turn in for Dover Harbour.Seamen sailing up the channel might use these lights, not as leading lights (as popular opinion has it), but simply as lights in transit when another bearing is needed to confirm position.It is also uncertain why two lights were built in 1840 to give a lead when a Trinity House lightship had been stationed at the South Sands Head since 1832 precisely for that purpose.