law: Indian Ports Act, 1908
  49. Power to impose hospital port-dues 
  (1) The 2[Central Government] may, by notification in
  
  the Official Gazette, order that there shall be paid in respect of every vessel
  
  entering any port subject to this Act, within a reasonable distance of which
  
  these is a public hospital or dispensary suitable for the reception or relief
  
  of seamen requiring medical aid such further port-dues not exceeding one anna
  
  per ton as the 2[Central Government] thinks fit.
  (2) Such port-dues shall be called hospital port-dues, and the 2[Central
  
  Government] shall, in making any order under sub-section (1), have regard to
  
  any contributions made under section 36, sub-section (5), clause (d).
  (3) An order imposing or increasing hospital port-dues shall not
  
  take effect till the expiration of sixty days from the day on which the order
  
  was published in the Official Gazette.
  (4) Whenever the 2[Central Government] is satisfied
  
  that proper provision has been made by the owners or agents of any class of
  
  vessels or giving medical aid to the seamen employed on board such class of
  
  vessels, or that such provision is unnecessary in the case of any class of
  
  vessels, it may, by notification in the Official Gazette, exempt such class of
  
  vessels from any payment under this Sections.