Section 12-130. Office hours

Except as otherwise provided by law, the office
  hours  in  all  public  offices  of  the city, and of all county offices
  within the city, shall be from nine o'clock antemeridian to five o'clock
  postmeridian. The head of a city  office  or  department,  or  a  county
  officer  who  comes within the foregoing provisions of this section, may
  adopt a rule that such office shall be closed  to  the  public  at  four
  o'clock  postmeridian, when in the judgement of such officer, the period
  between the hours of four o'clock postmeridian  and  five  o'clock  post
  meridian  is  required  for  the performance of the work in such office.
  During the months of July and August the office hours  of  such  offices
  shall  be from nine o'clock antemeridian to four o'clock postmeridian if
  the head of the office or department so orders. The office hours of  any
  such  office, however, shall be from nine o'clock antemeridian to twelve
  o'clock  noon  on  Saturday,  provided  that  the  commissioner  of  the
  department  of  finance may, in his or her discretion, adopt a rule that
  such office or department shall be closed to the public on Saturdays.