The base for the City levels for the City is hereby affixed and established according to the provisions herein contained. The base or datum plane for City levels shall be one hundred feet (100') below the center of a copper pin, three-tenths inches (3/10") in diameter, set into the west face of the east pilaster beside the stone arch forming the entrance to the City Hall in the City, said City Hall being located on the south side of the public square in the City, from which plane the grades, which shall hereafter be fixed and established, are to be computed. Said plane is to be denominated zero. (Ord. 22, 12-5-1908; amd. 1979 Code)