The mayor may upon any emergency, riot, pestilence, invasion or at any time he shall deem it necessary for the peace, good order or health of the municipality, order the chief of police to appoint reserve policemen for a specified time, not exceeding two days, without the approval of the commission. He may also, with the approval of a majority of the city commission, order the chief of police to appoint such number of reserve policemen as may be agreed upon by the commission, to serve upon days of election, public celebration and holidays, and said reserve policemen shall have and possess all the powers and privileges of regular policemen during the time for which they may be appointed. (Prior code § 4-1-9)