Special meetings of the council may be ordered by the chairman, a majority of the council or by the mayor. The order must be filed with the recorder and must be signed by the person or persons calling the special meeting and must be entered in the minutes of the council. Except in case of emergency, as declared by the mayor, not less than two (2) days' notice of any special meeting must be given by the recorder to each member not joining in the order, the notice of the meeting to be served personally or left at his or her usual place of abode. All regular meetings of the council, to which any person not a principal officer is admitted, must be opened to the public. (Prior code § 2-1-5(b))