An example of the 1827 edition of Thomas Martyn's large-scale map of Cornwall, which had been first published in 1748, together with the index to the map, published in 1816.

At the centre of the map sits an elaborate cartouche, with a dedication to the Prince of Wales, Duke of Cornwall, while the coats-of-arms of the 164 subscribers appear across the work. Inset on the left-hand side is a map of the Isles of Scilly, placed here because, were they to sit in their proper position, the - already substantial - map would be "too great a length". Top-right is an intricate compass rose, showing two surveyors, one using a theodolite, the other a waywiser. Also illustrated are tin, copper, and lead mines, hills, commons, rivers, and parks, churches, villages, farmhouses, roads, and lanes.

This diverse range of features - from parishes, to headlands, to creeks - is set out in the index in alphabetical tables, for "the ready finding them in the New Map of the said County".

Thomas Martyn (1695-1751) was a Cornish surveyor who began his career mapping the estates of the wealthy. His map of Cornwall took 15 years to complete and was financed by a subscription system, with subscribers making part of their payment in advance and part upon the completion of the map.

The map was first published by Robert Sayer in 1748, then republished by William Faden in 1784, with this example published by James Wyld, who had been Faden's apprentice and took over his business when he retired, in 1827. Wyld has added further detail to the map, as, for example, 'Low Lea', 'Cam Base', and 'Garguinus' in the bay that surrounds Penzance.

Rare:
We have only able to trace five institutional examples of the index and one institutional example, at the Bibliothèque Nationale de France, of the 1827 map.