The resolution authorizing such bonds shall provide for the levy and collection of a direct annual tax upon all the taxable property in said county sufficient to pay the principal thereof and interest on such bonds as the same respectively falls due, which tax for payment of such principal and interest shall be in addition to the maximum rate of taxation for all other county purposes now or hereafter permitted by the statutes of this state, and a certified copy of such bond resolution shall be filed with the county clerk of such county and it shall be the duty of such county clerk annually when extending taxes of said county levied for county purposes to extend taxes sufficient for the purpose of paying the principal of and interest on the bonds therein authorized as directed in and by said resolution, which tax so extended by such county clerk shall not be subject to any statutory limitation as to rate or amount and shall be in addition to the statutory maximum rate of taxation for all other county purposes.