After payment of any notes issued in anticipation of the sale of the bonds and after payment of the cost of preparing, marketing, and issuing the bonds, the proceeds of the sale of a bond issue shall be applied only to the purposes for which the issue was authorized. Any excess amount which for any reason is not needed for any such purpose shall be applied either (i) toward the purchase and retirement of bonds of that issue at not more than their face value and accrued interest, or (ii) toward payment of the earliest maturing installments of that issue, or (iii) in accordance with any trust agreement or resolution securing the bonds. (1917, c. 138, s. 31; 1919, c. 178, s. 3(31); C.S., s. 2957; 1921, c. 8, s. 1; Ex. Sess. 1921, c. 106, s. 1; 1927, c. 81, s. 38; 1971, c. 780, s. 1; 1973, c. 494, s. 28.)