—(1)  The common seal of the Polytechnic shall be in the custody of the Principal and shall not be affixed to any instrument, other than a diploma or an academic certificate, except in the presence of the Chairman or a member of the Council and the Principal who shall sign their names to the instrument in token of their presence before the common seal is affixed thereto and such signing shall be sufficient evidence that the common seal of the Polytechnic has been duly and properly affixed and that the seal is the lawful seal of the Polytechnic.