The Sankaty Head Lighthouse, a symbol of Nantucket, was in danger of falling into the Atlantic Ocean as the cliff eroded. The Sconset Trust, a local preservation group, has raised $3.5 million to move and restore it. The lighthouse, weighing 450 tons, was lifted off its foundation and is being pushed along on steel beams. At 62 inches every ten minutes it’s slow going, but it should reach its new home at the end of the week. The Coast Guard will then put the beacon back into service.