The board of aldermen shall have the power to levy, annually, taxes upon all taxable property within the city in addition to other taxes, and in sufficient amount for the purpose of paying the interest and principal as may become due on all bonds now issued and outstanding, and such taxes shall be collected in the same manner and time as other taxes. The mayor and board of aldermen shall also have power, by ordinance, to issue bonds payable in one year, to an amount not exceeding half the current revenue for the fiscal year, and also to issue bonds in renewal of other bonds of the city maturing for the requisite amount and which the city has no fund to pay. Such renewal bonds shall not bear a greater average rate of interest than did the original bonds, and shall not run for a longer time than ten years. The mayor and board of aldermen shall also have power, by ordinance, to issue bonds for the purpose of funding the floating indebtedness of the city existing at the time of its incorporation as a city of the fourth class. The mayor and board of aldermen shall have power, by ordinance, to issue bonds for the purpose of extinguishing or paying off any indebtedness against any such city of the fourth class; provided, such indebtedness has been contracted by and with the consent of the constitutionally required percentage of the voters voting in favor of the question and declared by any court of competent jurisdiction to be a legal and valid indebtedness, and which has or may hereafter become a judgment against such city. The aggregate amount of such judgment and existing indebtedness shall not exceed the constitutional limit of such city, and such bonds shall not bear any greater rate of interest than the rate per annum permitted by law, and shall not run for a longer time than twenty years.