All bonds, warrants and certificates of indebtedness shall be signed by the mayor, countersigned by the City Secretary, and sealed with the seal of the city in the manner provided by general law, and shall be payable at such times and place or places as may be fixed therein. It shall be the duty of the mayor, when such bonds are issued, to forward the same to the attorney general of the State of Texas for approval and for registration by the comptroller of public accounts.