It shall be the duty of the surveyor general to calculate the amount of purchase money, interest and fees, due on each unpatented tract; and after the descriptions of said tracts have been transmitted to the prothonotaries of the respective counties, and entered as hereinafter provided, the amounts so found to be due, together with five dollars for the labor and costs of making out and filing, shall form an aggregate sum which shall be entered in a lien docket to be provided and kept for that purpose, and said sum shall bear interest at the rate of six per cent.
64 P.S. § 463