Charles Boutelle, assistant to Alexander Bache, came to Edisto Island to prepare a master baseline for charting the eastern seaboard, an especially important task because Charleston depended on shipping through treacherous channels near its harbor. Only Edisto Island offered a straight line of adequate length, but despite an 1848 report that the area was secure from sea encroachment and needed little grading, Boutelle and his crew spent a month using hand tools to clear and level a twenty-foot-wide path stretching almost seven miles through dense maritime forest. After the path was prepared, Bache's team spent fourteen days in January 1850 carefully measuring the line by leapfrogging two Bache bars across the island on tripods, while laborers contracted from a local plantation cleared forest and croplands to make way for the work.