6. It shall be lawful for the Government from time to time to- (a) declare what ferries shall be deemed public ferries, and the respective districts in which, for the purposes of this Act, they shall be deemed to be situate; (b) take possession of a private ferry and declare it to be a public ferry; (c) establish new public ferries where, in its opinion, they are needed; (d) define the limits of any public ferry; (e) change the course of any public ferry; and (f) discontinue any public ferry which it deems unnecessary. Every such declaration, establishment, definition, change or discontinuance shall be made by notification: Provided that, when any alteration in the course or in the limits of a public ferry is rendered necessary by changes in the river on which such ferry is established, such alteration may be made, by an order in writing, by the Magistrate of the district.