Miss. Code § 19-27-33
The board of supervisors may employ some skilled person to establish at or near the courthouse a line not exceeding twenty chains in length, corresponding with the true meridian of the place, and simultaneously determine to within one-half of one second of an arc the geographical longitude of the station occupied by the instrument used in the operation. After the line has been established, the board of supervisors may appoint a competent person to make annual observations at such time as may be determined, to ascertain the declination of the magnetic meridian from the true meridian, and when any alteration is ascertained, the person making the observation shall report the particulars to the board of supervisors, and the same shall be entered on its minutes.
Miss. Code § 19-27-33