Special Acts for Railways, Harbours, &c. Special Acts for Railways, Harbours, &c. 8Powers for protection of navigation, &c. under local Acts for harbours, railways and other works on tidal lands, &c. to be exercised by Board of Trade. 9Power to Admiralty to retain authority over ports, &c. where dockyards, &c. are situate. 10Exception as to Mersey and Thames. Special Acts for Railways, Harbours, &c.