File contains confidential Admiralty Memoranda re: 'Instructions regarding Hostile Submarines' ; 'Submarines in Home Waters' ; 'Instructions regarding Use of Rifles and Machine Guns by Merchant Vessels for Defence against Aircraft and Submarines' ; 'A Suggestion for rendering ships of the Mercantile Marine immune from the effects of torpedo attack' ; profiles of British and German Submarines ; list of Irish Lights Stations electrically connected with Telegraph Service.