The mayor, or in his absence the mayor pro tem, shall take the chair precisely at the hour appointed for the meeting, and shall immediately call the commission to order. In the absence of the mayor or mayor pro tem, the city clerk or his assistant shall call the commission to order, and a temporary chairman shall then be elected by the members of the commission present. Upon the arrival of the mayor or mayor pro tem, the temporary chairman shall immediately relinquish the chair upon the conclusion of the business immediately before the commission. (Prior code § 2-1.4).