William Roy

William Roy

General William Roy (1726 – 1790), was a Scottish military engineer, surveyor, and antiquarian. He was an innovator who applied new scientific discoveries and newly emerging technologies to the accurate geodetic mapping of Great Britian.

It was Roy's advocacy and leadership that led to the creation of the Ordnance Survey in 1791, the year after his death. His technical work in the establishment of a surveying baseline won him the Copley Medal in 1785. His maps and drawings of Roman archaeological sites in Scotland were the first accurate and systematic study of the subject, and have not been improved upon even today. Roy was a Fellow of the Royal Society and a member of the Society of Antiquaries of London.

Early life and family

Roy was born in Carluke Parish in South Lanarkshire in 1726, and was educated in the parish school and Lanark grammar school. There is no record of his further education, but circumstances strongly suggest that he obtained one. He was a respected land surveyor at Craigforth near Stirling prior to his work for the military, and his demonstrated knowledge of general science, geodesy, chemistry, and astronomy imply that he was once an apt pupil within a formal system of education.

Roy's father had been a steward or factor (ie, a representative of a landowner in Scotland) in the service of the Hamiltons of Hallcraig, as well as an elder of the Kirk. His grandfather had held a similar position as factor, and his uncle acted in that capacity for the Lockharts of Lee. His younger brother James had held the bursary in the Grammar School and College of Glasgow, took a Master of Arts after studies in the Languages and Philosophy, was licensed by the Presbytery of Glasgow, and held several other notable positions before his untimely death in 1767, at the age of 37.

Roy maintained his connections to his birthplace and the people living there. A servant for the Lockharts of Lee recalled his visits there over time, as his national reputation grew. She noted that at first he would dine in the servants hall, in later years he would dine with the family, and later on still he would be seated at the right hand of the Laird.

Career and later life

In 1747 Lieutenant-Colonel David Watson, Deputy Quartermaster-General, proposed the compilation of a map of the Scottish Highlands to facilitate the subjection of the clans following the Jacobite rising of 1745. In response, King George II commissioned a military survey of the Highlands, and Watson was placed in charge under the command of the Duke of Cumberland. Among his assistants were William Roy, Paul Sandby, and John Manson. The labours of Watson and Roy, and of Roy in particular, resulted in The Duke of Cumberland's Map, now in the British Museum. The map reflects Roy's lifelong interest in ancient Scottish history by showing the locations of ancient Roman remains, primarily military camps, wherever he encountered them.

Roy was first mentioned in connection with this effort in a 1749 letter, by which time he was Assistant to the Deputy Quartermaster-General, but without a military commission. He would continue to work on the survey until 1755, and was then given a military commission and the title of Practitioner-Engineer. He was promoted steadily, reflecting acknowledgement of his considerable technical talents.

Roy's technical abilities and willingness to innovate brought him to the favourable attention of Duke Ferdinand of Brunswick, the Commander-in-Chief of the Allied army at the Battle of Minden in 1759. Preparatory to the battle, the various military engineers made drawings of each step of the coming battle, with each step drawn on a different sheet of paper. The commander could then study the course of the battle before it occurred, going from one sheet to the next. Lieutenant Roy, however, made his drawings on a single sheet with coordinated and accurate overlays, so that the commander could more easily study the course of the battle by examining a single sheet of paper. The commander's comprehension was greatly facilitated, and Roy's methodology was soon adopted as an advancement in military science. Roy was promoted to captain in the Corps of Highlanders a scant three weeks after the battle.

The next year he became a Deputy Quartermaster-General and major of foot, and was promoted to lieutenant-colonel in 1762. In 1765 he appears as a Deputy Quartermaster-General, Surveyor-General of Coasts, and Engineer-Director of military surveys in Great Britain, and in that capacity he visited Ireland in 1766 and Gibralter in 1768. He became a Fellow of the Royal Society in 1767.

Roy was promoted to colonel in 1777, and to major-general in 1781. He was in charge of the departments of the Quartermaster-General and Chief Engineer in 1782, and in 1783 became the Director of Royal Engineers. In 1783-84 he conducted observations for determining the relative positions of the French and English royal observatories. His measurement of a base-line for that purpose on Hounslow Heath in 1784, the germ of all subsequent surveys of the United Kingdom, gained him in 1785 the Copley medal of the Royal Society. Roy's measurements (not fully utilised until 1787, when the Paris and Greenwich observatories were properly connected) form the basis of the topographical survey of Middlesex, Surrey, Kent and Sussex. These surveys were made for the most part using the new Ramsden theodolite which Roy had commissioned from Jesse Ramsden, and were the start of the Principal Triangulation of Great Britain.

He was finishing an account of this work for the Philosophical Transactions of the Royal Society when he died.



Roy's use of scientific advancements and accurate mathematical formulas paved the way for modern geodesic surveying. His tenure and his work are the dividing line between older, approximate mappings and newer, highly accurate ones in Britain. He is cited repeatedly in early nineteenth century mathematics textbooks for his use of spherical trigonometry in surveying. Early twentieth century technical books on modern surveying and geodesy include Roy's work as the historical starting point for the modern profession.


Roy's maps and his drawings of the relics of the Roman presence in Scotland were immediately seen as credible and valuable. For sites where the Roman remains were later destroyed by human development, his drawings are the only reliable record of their existence.

Roy was the first to systematically map the Antonine Wall and provide accurate and detailed drawings of its remains, an effort undertaken in 1764.

Historical work

His only historical work, Military Antiquities of the Romans in Britain, has a mixed reputation. His drawings and maps are held in the highest regard as still-valuable research sources. However, his efforts in the scholarly discussion of history are widely held to be without value, largely through no fault of his own. This was due to his belief that the spurious fraud De Situ Britanniae was a genuine work, a view shared by virtually all of his contemporaries. Roy consequently adjusted his perspective to be consistent with the history as told in the fraud, causing his own conclusions to be without a valid foundation. Much of Roy's research was devoted to the attempt to follow ficticious journeys throughout Scotland that were described in De Situ Britanniae.

That Roy's considerable talents were partially wasted is a tragedy. He was a Scot with a lifelong interest in ancient Scottish history, and his technical ability and scientific knowledge made him uniquely qualified to provide information in an area of history where knowledge and understanding are minimal. That loss for Scottish history has been bemoaned by Scottish historians. In his introduction to Celtic Scotland, Skene deprecates those historical works based on De Situ, including Roy's, but adds for him alone the comment that " ... perhaps more to be regretted, the valuable work of General Roy ...

Minor biographical note

While Roy was a famous and notable person by the time of his death, some of the minor details of his military career have been susceptible to error in later articles about him, usually in a way that enhances Roy's actual status as a young, non-military assistant and surveyor. Among these, a 1793 obituary says he held the rank of Colonel of Artillery in 1746, whereas he was then a 20-year-old surveyor with no military commission, and who was never connected with the artillery. An 1885 book about Western Scotland with a chapter on Roy's life has him a Colonel in the British Army who was trusted with the work of mapping the Highlands in 1747 by his commanding general. Roy deserves much of the technical credit for the map that resulted, but he was actually a non-military assistant to a Lieutenant-Colonel who was a Deputy Quartermaster-General. An 1874 book on the history of Carluke Parish and its people has Roy himself the Deputy Quartermaster-General.

The written history of the Royal Engineers makes a minor contribution to the list of errors, stating in passing that Roy was the nephew of his immediate supervisor in 1747, and was given the rank of Lieutenant. Roy was not related to David Watson, nor was he in the military at that time. The author has confused him with David Dundas, who was the son of Watson's sister, and who joined his uncle in 1752.

Partial bibliography

Roy was an exceptionally neat and capable draughtsman, and often made maps of the survey work conducted by others, as well as maps of his own survey work.

In the British Museum

  • The Duke of Cumberland's Map (1747)
  • A General Description of the South Part of Ireland, or Observations during a Short Tour in Ireland (1766)

Maps and Plans drawn between 1752 and 1766

  • Roman Post at Ardoch
  • Culloden House
  • Roman Camp, Dalginross, Genearn
  • Esk River
  • Kent, New Romney to North Foreland
  • Louisbourg
  • Milford Haven
  • Roman Temple at Netherby, Cumberland
  • Stratgeth Roman Post, near Innerpeffrey, Strathearn
  • Coast of Sussex
  • Southeast part of England
  • Country between Guildford and Canterbury
  • Hindhead to Cocking
  • Lewes Road from Croydon to Chailey
  • Country from Dorchester to Salisbury
  • Country from Gloucester to Pembroke
  • Marden Castle, near Dorchester


  • Experiments and Observations made n Britain in order to obtain a Rule for measuring Heights with the Barometer (1778)
  • A paper on the baseline used in determining the relative positions of the observatories in Paris and Greenwich, in Transactions of the Royal Society (1785)
  • An Account of the Mode professed to be followed in determining the Relative Situations of the Royal Observatories of Greenwich and Paris (1787)
  • An Account of the Trigonometrical Operations by which the Distance between the Meridians of the Royal Observatories of Greenwich and Paris has been determined (1790, for the Royal Society)
  • Military Antiquities of the Romans in Britain, and particularly their Ancient System of Castramentation illustrated from Vestiges of the Camps of Agricola existing there (1790, published posthumously in 1793)



External links

    • - the letter refers to Roy by name as "... our trusty and well beloved Lieutanant-Colonel William Roy, one of our engineers for inspecting, surveying, and making reports from time to time of the state of the coasts and districts of the country adjacent to the coasts of this kingdom, and the islands hereunto belonging."

      • - a literary review of Roy's book

        • - an early account of the Survey of England

          • - a literary review of Roy's book

            • - a discussion of Roy's work that won him the Copley Medal.

              • - the new council of the Royal Society, with "Major Gen. W. Roy" as one of the new members of the council.

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