That upon the issuance of any warrant on said fund the same shall be presented to the city treasurer for payment and if there is then sufficient money in said fund to pay said warrant he must then pay the same, but if there is not sufficient money in said fund to pay such warrant he must endorse on said warrant the words "not paid for want of funds," the date of the endorsement and his signature. That from and after the date of such endorsement said warrant shall draw interest at the rate of 4 percent per annum and until paid as hereinafter provided. (Ord. 82, § 5, 1938.)