16 Filling of vacancies on Board Subject to this Part, on the death of, or the vacation of office by, a member of the Board, the President may appoint a person to fill the vacancy: Provided that, if the number of members is fewer than the minimum number of members specified in section twelve, the President shall appoint a person to fill the vacancy. 17 Chairman and vice-chairman of Board (1) The President shall designate one member as chairman of the Board and another member as vice-chairman. (2) The vice-chairman of the Board shall exercise the functions of the chairman whenever there is a vacancy in the office of chairman or the chairman is for any reason unable to exercise his functions. 18 Co-opted members of Board With the approval of the Minister, the Board may co-opt any person to the Board: Provided that⎯ (a) a person shall not be co-opted to the Board if he is disqualified from membership of the Board in terms of section thirteen; (b) a co-opted person shall have no vote in any decision by the Board. 19 Meetings and procedure of Board (1) Subject to this Act, the Board shall meet for the dispatch of business and adjourn, close and otherwise regulate its meetings and procedures as it thinks fit: Provided that the Board shall meet at least four times annually. (2) The chairman of the Board may himself at any time and shall, at the request in writing of not fewer than two members, convene a special meeting of the Board, which meeting shall be convened at a date not sooner than seven days nor later than thirty days after receipt of such request. (3) Subject to subsection (4) the chairman of the Board or, in his absence, the vicechairman, shall preside at meetings of the Board. (4) If the chairman and vice-chairman are both absent from a meeting of the Board, the members present may elect one of their number to preside at that meeting as chairman. (5) A majority of members shall form a quorum at any meeting of the Board. (6) All acts, matters or things authorised or required to be done by the Board may be decided by a majority vote at a meeting of the Board at which a quorum is present. (7) At all meetings of the Board each member present shall have one vote on each question before the Board: Provided that— (a) in the event of an equality of votes, the chairman or person presiding shall have a casting vote in addition to his deliberative vote; (b) no member shall take part in the consideration or discussion of, or vote on, any question before the Board which relates to his vacation of office as a member. 19