John Hamilton Moore (1738–1807), a well-known teacher of navigation, was born in Edinburgh, educated in Ireland, and subsequently joined the Royal Navy at Plymouth. In about 1770 Moore established a Nautical Academy in Brentford, Middlesex, and in 1772 he published his popular epitome of navigation under the title The New Practical Navigator and Daily Assistant. Later he established himself at 127, Minories, near Tower Hill, where he not only taught navigation to ‘Gentlemen designed for, or belonging to the sea‘ but carried on the business, aided by his sons and son-in-law Robert Blachford, of chart-seller and purveyor of nautical instruments. In the preface to the twelfth (1796) edition of his Practical Navigator, Moore presumed that he had been enabled to have made gradual but progressive improvements in navigation as his ‘knowledge became extended through investigation’ and as his ‘judgement matured by experience’. In this edition of his work Moore styled himself as ‘Teacher of Navigation, Hydrographer and Chart-seller to His Royal Highness the Duke of Clarence’. There can be no doubt that Moore's Practical Navigator was favourably received; and, indeed, a twentieth edition was brought out by Joseph F. Dessiou (1790–1842), a master in the Royal Navy who, on retiring from sea-service, was employed in the Admiralty Hydrographic Office where he specialized in the study of tides. Dessiou's twentieth edition of Moore appeared in 1828, some 21 years after the death of its original author.