During the 1745 Rebellion, government military commanders had been “greatly embarrassed for want of a proper Survey of the Country” . The rebellion ended at the Battle of Culloden in April 1746. L.Col. David Watson, the Deputy Quartermaster-General in the Board of Ordnance then advised the Duke of Cumberland that a country-wide military survey should be conducted. Cumberland was George II’s son. He successfully petitioned the King and in 1747 Watson was instructed to begin work on a pilot project. He delegated the task to a bright young man in his department. William Roy noted, ‘As Assistant Quartermaster, it fell to my lot to begin... the execution of that Map’. He worked under Watson but soon assumed responsibility for the day-to-day administration and also for production of the mapped ‘protractions.’
The base was Fort Augustus. Roy was paid 4 shillings a day. Soldiers were preferred to civilians for the surveying parties. Roy argued that some time earlier ‘rude persons’ in Ulster had cut off the head of an English land-surveyor and furthermore, soldiers were ‘more useful, being subject to military command, and would be the cheapest.’ NCOs and men were recruited for their qualities of “carefulness and sobriety”. There was a shortage of army engineers at the time partly due to a parallel initiative of road building by General Wade’s successor, Major Caulfield. For the first two years Roy was the only technical surveyor but thereafter was joined by several new young graduates of the military academy in Woolwich. In time Roy was able to organise six surveying parties as more engineers were recruited. Each party, under the engineer officer, comprised an NCO and six troopers; one carried the circumferentor, a primitive theodolite, two were chain men, two were guards (one at the fore and one at the rear) and the remaining man acted as a runner. Arrowsmith describes the approach: ‘The course of all the Rivers and numerous Streams were followed to the Source, and measured, all the Roads and the many Lakes of Salt-water and Fresh-water were surveyed, as well as such other intermediate Places and Cross-lines as were found necessary for filling up the Country; and intersections being taken at the Right and the Left, ascertained by innumerable minute Situations.’ Skeltonpresumes, therefore, that fore and back bearings were taken onto staves held at points along the route, and cross-bearings taken on prominent lateral features. All the rest was drawn by hand into sketch books i.e. relief, boundaries, enclosures, plantations, towns and settlements. Clearly rivers, lochs, coastlines, bridges and roads were of military importance and measured with more accuracy than farms, settlements, fields and forests.Triangulation networks were not used. Each engineer carried both a notebook and a sketch book. Sadly none of these books has survived. Each surveyed section required assessment, discussion and careful adjustment to link to adjacent recordings. (‘closing the traverses’) There was no grid system, but a simple orientation to magnetic north.
The Highlands survey ,above the Forth-Clyde isthmus, was completed by 1752. Roy’s team was enhanced by the arrival of David Dundas. Two survey parties then embarked on the Lowland survey. Roy took the East and Dundas took the West. In the event, the Lowland work became somewhat hurried because of the outbreak of the Seven Years War. In 1755 both Roy and Dundas were commissioned, promoted and transferred to London. The Survey was deemed complete although Roy expressed some unhappiness with the final product.
Surveying was a summer activity. Each winter Roy returned to the Board offices in Edinburgh Castle where the original protraction maps were prepared from the notebooks and sketchbooks of the surveyors. This process was done in collaboration with Paul Sandby, the senior draughtsman on the project. He was Roy’s contemporary and had been working for the Board of Ordnance based at the drawing-room in the Tower of London. In the aftermath of the the rebellion he was transferred to Edinburgh. Sandby was later to become a watercolour artist of renown and his paintings from the same period reflect his influence on the style of the maps and the soft colour choices. He was certainly responsible for the impressive relief-washes which are so characteristic of the maps.
The maps were constructed at 1000 yards to the inch, although there was no note of this scale. There were 84 rolls of the Highland section and 10 rolls of the Lowlands. In addition a Fair Plan of the Highland section was prepared on 12 rolls. Much of the detail is much clearer on the protracted maps than on the fair copy. Sandby was transferred to England in 1751 but recalled in 1753 to Edinburgh, in order to produce a further ‘reduced copy’. This was composed at 4,000 yards to the inch. Roy reported frequently to Colonel Watson, who remained nominally in charge. Each spring, Watson met the team at Edinburgh Castle before carrying an updated report South to London.