Any person desiring the services of a special policeman in or about his property or place of business, upon agreeing to defray all expenses of maintenance of such special policeman, upon application to the commission may have any suitable person named for such special policeman duly appointed as such. Such special policeman shall take the usual oath of office and shall have the powers of a regular police officer in and upon the premises for which he may have been appointed, but not elsewhere; provided, however, special police officers so appointed shall be under the control of the chief of police. The person at whose instance such officer was appointed shall be responsible for the pay of such officer, and the city shall in no case incur any liability whatever by reason of the appointment of such special policeman. No person appointed as a special policeman under the terms of this section shall be considered a member of the police department. All special or reserve police officers shall wear a shield having inscribed thereon, "Special Policeman," while on duty. It is unlawful for any special police officer to wear his badge or shield when he is not performing the duties for which he was employed. (Prior code § 4-1-10)