In order to provide for the payment of the cost and expense of such improvements, the councils of the cities of this commonwealth may, from time to time, issue their bonds in such sums as may be required, in all to an amount not exceeding the cost and expense of such improvement and interest thereon.
Said bonds shall bear the name of the street or alley to be improved. They shall be payable at a period not less than five years from the date of their issue, to be provided in the ordinance directing the improvement, and bear interest at a rate not exceeding six per centum per annum, payable semi-annually, on the first day of July and January.
53 P.S. § 1802