Letter from J M Martin, Musgrave House, Richmond, Surrey, to the Assistant Secretary of the Royal Society, Burlington House, London Martin thanks for the 'kind remittance' of Mr Murray's paper on the tides of the north sea. In 1837-8 a series of levels were taken at various points on the British Channels by the Dr Whewell to determine the height of the sea. Martin enquires if subsequent observations have been made to see if any changes in the levels have been made. 7 June 1905