law: Cantonments Act, I924 
  16.Filling of vacancies:- 
  (1) Vacancies arising by efflux of time in the
  
  office of an elected member of a Board shall be filled by an ordinary election
  
  to be held on such date as the {Subs.by the A.O.1937, for " L.G." }
  
  [Central Government] may, by notification in the Official Gazette, direct.
  (2) A casual vacancy shall be filled by a
  
  casual election the date of which shall be fixed by the {Subs.by the A.O.1937,
  
  for " L.G." } [Central Government] by notification in the Official
  
  Gazette, and shall be, as soon as may be, after the occurrence of the vacancy :
  Provided  that no casual election shall be held
  
  to fill a vacancy occurring within three months of any date on which the
  
  vacancy will occur by efflux of time, but such vacancy shall be filled at the
  
  next ordinary election.