¹[13. (1) Every such contract shall be made by the Chairman on behalf of the Authority: Provided that a contract involving expenditure exceeding Taka five lakhs shall not be made by the Chairman without the previous sanction of the Authority. (2) Every estimate for expenditure of a sum for carrying out the purposes of this Ordinance, all specifications of work and of the material or goods to be supplied and the conditions of the contract shall be approved,- (a) where the expenditure involved does not exceed Taka five lakhs, by the Chairman; and (b) in other cases, by the Authority. (3) Sub sections (1) and (2) shall apply to every variation or abandonment of a contract or estimate as well as to an original contract or estimate.]