Section 57. Additional powers and duties

The mayor shall have such other
  powers and perform such other  duties  as  may  be  prescribed  in  this
  chapter  or  by  other  laws  of the state or by ordinance of the common
  council, not inconsistent with law. In case of  riot,  conflagration  or
  other  public emergency requiring it, the mayor shall have power to call
  out the police and firemen; he shall also have  power  to  appoint  such
  number  of  special  policemen  as he may deem necessary to preserve the
  public peace. Such special policemen shall be under the sole control  of
  the   regularly   appointed  and  constituted  officers  of  the  police
  department. They  have  shall  have  power  to  make  arrests  only  for
  disorderly  conduct  or  other  offenses against peace or good order. In
  case of riot or insurrection, he may take command of  the  whole  police
  force, including the chief executive officer thereof.