Letter from [Arthur] Mostyn Field, Hydrographic Department, Admiralty, Whitehall, London, to the Assistant Secretary of the Royal Society, Burlington House Informs instructions are being issued to officers in command of HM Surveying vessels 'relative to the investigations of areas of magnetic disturbance' and it is 'desirable' to give an example of this type of work. A paper from the Proceedings on "The investigation of an area of magnetic disturbance in East Loch Roag" is suitable for this, however as there are no copies available Field requests it be reprinted as a 'Departmental Admiralty Document'. 29 March 1906