14. (1) Every contract made by the Chairman on behalf of the Authority shall be entered into in such manner and forms as would bind the Chairman if such contract were made on his own behalf, except that the common seal of the Authority shall be used; and every such contract may in the like manner and form be varied or discharged. (2) Every contract for the execution of any work or the supply of any materials or goods shall be in writing and shall be sealed. (3) The common seal of the Authority shall remain in the custody of the Secretary to the Authority and shall not be affixed to any contract or other instrument except in the presence of a Member (other than the Chairman), who shall attach his signature to the contract or instrument in token that the same was sealed in his presence. (4) The signature of the said Member shall be in addition to the signature of any witness to the execution of such contract or instrument. (5) A contract not executed as provided in this section shall not be binding on the Authority.