The members and clerk of the board shall receive the same per diem compensation and actual and necessary traveling expenses as are allowed to members of the board of supervisors of the county. The per diem and mileage of the board, the county clerk when serving as clerk of said board and its members, when certified by the board to the county treasurer, shall be paid from the general fund of the county, and the board of supervisors of the county is hereby authorized and empowered to raise by taxation amounts necessary for such purposes: Provided, however, That no member of the board or the county clerk when serving as clerk of said board shall receive compensation for their services for more than 20 days in any one year unless otherwise authorized by resolution of the board of supervisors.