29. Every police-officer who shall be guilty of any violation of duty or wilful breach or neglect of any rule or regulation or lawful order made by competent authority, or who shall withdraw from the duties of his office without permission, or without having given previous notice for the period of two months, or who, being absent on leave, shall fail, without reasonable cause, to report himself for duty on the expiration of such leave, or who shall engage without authority in any employment other than his police-duty, or who shall be guilty of cowardice, or who shall offer any unwarrantable personal violence to any person in his custody, shall be liable, on conviction before a Magistrate, to a penalty not exceeding three months` pay, or to imprisonment with or without hard labour, for a period not exceeding three months, or to both.