1. The said waterworks plant and system, when acquired, shall be subject to the control and management of a board known as "The Board of Waterworks Commissioners", who shall have the power to issue to the person, firm or corporation, in payment for said waterworks system, bonds in such denomination as may be stated in the proposition to the city or as may be determined by the board, which bonds shall refer to and recite sections 91.090 to 91.300, as authority for their issuance, and shall be signed by each member of the board, attested by the secretary, under the seal of the board, and each bond shall contain substantially the following, among other appropriate recitals therein:
2. The said bond shall run for a period of twenty years and draw interest at the rate of six percent per annum, payable semiannually, said interest to be evidenced by the coupons attached. The bonds and coupons shall be negotiable in form. The coupons may be signed only by the lithographed signatures of the president of the board and the secretary thereof.