The assessor may, with the approval of the board of supervisors of the county, appoint deputies, who shall take the oath of office, and shall be required by the assessor to give bond to him in an amount not less than Ten Thousand Dollars ($10,000.00) for the faithful discharge of their duties. The appointment shall be in writing, filed with the clerk of the board of supervisors, whose approval shall be entered on the minutes of such board.