Because of the additional duties which have been imposed on the circuit clerk, license collector, sheriff, collector of revenue, treasurer, and recorder of deeds in cities not within a county by such cities, the board of aldermen of any such city, upon the approval of the board of estimate and control of any such city, may pay such officials an additional sum in an amount to be determined by the board. The additional compensation allowed under this section shall be in addition to other compensation provided by law for such officials and shall be paid in the same manner as such other compensation.