Aaron Arrowsmith's large and detailed map of Ireland. The most accurate map of Ireland to date.

Aaron Arrowsmith (1750-1823), ​"easily the foremost cartographer of his time" (R.V. Tooley), was the founder of the Arrowsmith dynasty of cartographers. Born in County Durham, he was in London by 1777 when he witnessed the will of Andrew Dury, a mapseller and publisher, and was probably training with him; he may have trained with William Faden, Geographer to the King, but was certainly employed by John Cary in 1782, as he is credited with the survey work for ​'Cary's Actual Survey, of the Great Post Roads between London and Falmouth', published in 1784; he is frequently credited with some of the survey work for Cary's county atlas, ​'Cary's New and Correct English Atlas: being a set of county maps from actual surveys' (1787), but the sources are silent on this and by this time Arrowsmith had established his own business.

Arrowmsith's maps set a new standard; he was assiduous in analysing and verifying his sources, discarding not only the fictional but also the uncertain, going to printed and manuscript sources for his information, and engraved in a clear and highly legible style. Arrowsmith was also diligent in revising and improving his maps to keep them current, and served as an inspiration for the next generation of (particularly American) surveyors.

This is the second state of the map - as outlined by Bonar Law - is now dedicated to 'His Majesty' rather than 'H.R.H. the Prine of Wales', and to the imprint is added, 'Additions and Corrections to 1821'. The map shows an more accurate depiction of the Grand Canal.