Such assessment shall be payable at the city treasurer's office in equal, semi-annual instalments, with interest, at the rate provided in said bonds, from the date to which interest was computed on the amount of the assessments, or so much as remains unpaid from time to time, until all said assessments and interest are fully paid. The money so received by the city treasurer shall be applied to the sinking fund.
53 P.S. § 1806