The boundary lines of Baker County are as follows: Beginning at a point at center of township four south, on range line dividing ranges eighteen and nineteen east; thence north on said range line to the Georgia line; thence easterly on said Georgia line to the St. Marys River, and then down said river, concurrent with the boundary line between the States of Georgia and Florida, to where the said river intersects with range line dividing ranges twenty-two and twenty-three east; thence south on said range line to the center line of township four south; and then west on said township line to the point of beginning.