If it appears from the returns of such question that the constitutionally required percentage of the voters of such municipality were in favor of incurring such indebtedness, the council, board of aldermen or board of trustees shall pass an ordinance reciting the submission of the question and the result thereof, both for and against the question, and if the result, as certified, shall be in favor of the issuing of the bonds, then the council, board of aldermen or board of trustees in the same ordinance shall direct the issuance of such bonds to the amount of the debt so authorized to be incurred and shall, either before or at the time of doing so, provide for the collection of an annual tax sufficient to pay the interest on such indebtedness as it falls due and also to create a sinking fund for the payment of the principal thereof within twenty years from the date of contracting the same.