Every city issuing bonds under the provisions of sections 95.465 to 95.500 shall, before or at the time of doing so, provide for the collection of an annual tax, which, together with all sums which shall be applicable to the payment of the principal and interest of the said bonds, shall be sufficient to pay the interest of the said bonds, as it falls due, and also to constitute a sinking fund for the payment of the principal thereof at the maturity thereof. Such sinking fund shall be kept invested and managed in the same manner as the other sinking funds of such city.