2006 New York Code - Appointive Officers.

 
    § 12. Appointive  officers.  There  shall  be appointed by the mayor a
  corporation  counsel,  city  engineer,  commissioner  of  public  works,
  commissioner of public safety, commissioner of public welfare and sealer
  of  weights  and measures.   The commissioner of public welfare shall be
  appointed in accordance with  the  provisions  of  section  one  hundred
  sixteen  of  the social welfare law.  Other officers may be appointed as
  provided in this chapter or otherwise by law.  All appointments  to  any
  city  office  shall  be evidenced by a certificate in writing, signed by
  the appointing officer and filed forthwith in the  office  of  the  city
  clerk.  If an appointment be made by the common council such certificate
  shall be signed by the officer presiding at the time the appointment was
  made and attested by the city clerk.