The council of the said city shall have the right to bond the said city for the purpose of paving the streets and alleys of said city and for constructing waterworks and a sewerage system for the same, and for the purpose of providing hose and other appliances for extinguishing fire, and for any and all public improvements, whenever the council thereof may deem improvements necessary, and to refund outstanding bonds at a lower rate of interest, and to issue new bonds for the purpose of increasing the length of the time on any such indebtedness, but the aggregate indebtedness of said city, for all purposes, shall not at any time exceed five per centum of the assessed valuation of the taxable property therein, based upon the valuation of the last assessment next preceding the date of incurring said indebtedness; and the said council shall by taxation, provide a fund for the payment of interest on any and all indebtedness incurred in the manner aforesaid within the period of thirty-four years; provided, that no debt shall be incurred hereunder until the question of a bond issue be submitted to a vote of the people and the issuance thereof authorized by a three-fifths votes. Such bonds shall not be sold for less than par, nor exchanged for the evidences of indebtedness of said city except dollar for dollar. The method of issuance and proceedings for conduct of election, shall, except as otherwise provided in this act, be in the manner and form provided by Chapter Forty-Seven-A of the Code.