The mayor shall serve as the president of the board of aldermen. He shall have no vote on any matter except when the board of aldermen is equally divided, in which case he shall cast the deciding vote. The board of aldermen shall elect a president pro tempore who shall preside at the meetings of the board of aldermen in the absence of the mayor. When directed by the mayor or in the event of the mayor’s incapacity, the president pro tempore shall serve as acting mayor. While presiding over the board of aldermen or serving as acting mayor, the president pro tempore shall retain his vote on the board of aldermen. (Acts 1951, Ch. 539, § 12; Res. No. 21-81, § 1, 5-14-81)