The first Ordnance Survey Map, One inch to the mile, 1822
Published 1st August 1822 by Major Colby, Tower. Engraved at the Drawing Room in the Tower under the Director of Major Colby, by Benjamin Baker & Assistants. The Writing by Ebenezer Browne.
After the Jacobite rebellion of 1745, the Duke of Cumberland realised that the army had no decent maps to help track down escaped rebels. Two years later, King George II charged Lieutenant-Colonel David Watson with carrying out a military survey of the Highlands in order to finish off Cumberland’s work of subjugating the clans. A detailed drawn map scaled at one inch to 1,000 yards resulted. Among Watson’s assistants was William Roy (1726–1790) who repeatedly made suggestions that the rest of the British Isles should also be mapped out at a scale of one inch to one mile. His proposals were repeatedly rejected on grounds of expense. *
In 1783 the Royal Societies of London and Paris decided to resolve a long-running dispute about the relative positions of their observatories by connecting them by a system of triangulation, at the time the only way to measure distances and positions accurately. William Roy, now Major-General of the Royal Engineers, played a leading role in this project, which became known as the Principal Triangulation of Great Britain (1783–1853), assisted by men of the Royal Artillery. The military connection lasted until 1983.
Roy commissioned a new measuring tool to carry out the job, the complex and sophisticated Ramsden theodolite, which could measure distances both horizontally and vertically. He used this new tool to create a new base line in the middle of Hounslow Heath, just west of Chiswick. He dreamt that from there, eventually the whole country could be measured out, creating “a map of the British Islands” that would be “greatly superior in point and accuracy to any that is now extant.”
The Duke of Richmond, then Master-General of the Ordnance, in charge of all the forts and munitions of the Army and Navy, a sort of early predecessor of the Ministry of Defence, was impressed with the Ramsden theodolite and authorised the purchase of a second instrument for £373 14s on 21 June 1791. This date is now considered the foundation date of the Ordnance Survey.
Mapping began with the coastlines, as these were of the utmost importance for the defence of the realm. Publication began in 1801 in Kent but didn’t get to Chiswick until 1822 (after being withdrawn from sale between 1811 and 1816 for fear that they might be helpful to a planned Napoleonic invasion). This ‘Old Series’ consisted of 110 sheets, with the Isle of Man only published in 1873.**
Surveyors worked on a scale of two inches to one mile, which was reduced to one inch to one mile when printed, and engraved ‘in reverse’ on copper plates. There was usually a ten- to fifteen-year time lag from survey to publication, something hard to comprehend nowadays. The public could buy maps either directly from the Ordnance Survey at the Tower of London, or from one specialist map seller at Charing Cross, but at three guineas (£3 3s) per map they were not cheap.
This map of 1822 therefore represents one of the very earliest Ordnance Surveys of the Chiswick area, done at a smaller scale of one inch to one mile than later OS maps.
Acknowledgements: ©Crown Copyright 1822. From the collections at London Metropolitan Archives, City of London.
* See Richard Oliver, Ordnance Survey Map: A Concise Guide for Historians, The Charles Close Society for the Study of Ordnance Survey Maps, 2005
** J.B.Harley, The Historian’s Guide to Ordnance Survey Maps, reprinted from The Amateur Historian, with additional material, published for the Standing Conference of Local History, Blackfriars Press, 1964; J.B.Harley, Ordnance Survey Maps: A descriptive manual, Southampton Ordnance Survey, 1975