A short history of the Ordnance Survey of Great Britain The formal ‘foundation date’ for the Ordnance Survey is usually taken to be June 1791, but its origins lie further back. What some writers have taken to be the starting point is a survey of Scotland at one inch to 1000 yards (1:36,000) executed between 1747 and 1755 as part of pacification operations following the Jacobite uprising of 1745-6. This survey remained in manuscript until 2007, when a facsimile was issued. The instigator appears to have been Col David Watson, an officer in the Army and also in the Engineers of the Board of Ordnance, (which until 1855 was a separate organisation). It was the first governmentmade survey of a substantial tract of Great Britain, and one of the participants was William Roy (1726-90). In 1763, 1766 and 1783 Roy made proposals for an official survey of Britain, to be published at either one inch or one and a quarter inches to one mile (1:63,360 or 1:51,138), which might have re-used some of the work done for the military survey of Scotland, but all these proposals failed because the cost was considered excessive, and by the 1780s a considerable number of counties had been mapped commercially at 1:63,360, to varying standards. The real start of work which can be recognised as ‘Ordnance Survey’ came in 1783-4, when the Royal Societies of London and Paris agreed to settle a long running dispute as to the relative positions of the astronomical observatories in these two cities by connecting them by a system of triangulation. Triangulation is a means of measuring distance and fixing positions on the basis of measuring a single base and as many angles as may be necessary; if one side and two angles of a triangle are known, the remaining sides can be found by calculation. Until the recent advent of satellite positioning systems, triangulation was the universal means of providing a skeleton for controlling survey operations, and was the only feasible way of measuring distances across water and other obstacles where ground measurement, by chains or tapes, was impracticable. The English part of the operations was under the Roy’s direction: he was now a Major-General and the leading geodesist of the day. Though the enterprise was civil in nature, he was assisted by men of the Royal Artillery.
Posted on: Thu, 21 Aug 2014 15:11:16 +0000
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