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A plan of the cities of London and Westminster, and borough of Southwark is a 1746 map of the City of London and surrounding area, surveyed by John Rocque and engraved by John Pine. Rocque combined two surveying techniques: he made a ground-level survey with a compass and a physical metal chain – the unit of length also being the chain. Compass bearings were taken of the lines measured. He also created a triangulation network over the entire area to be covered by taking readings from church towers and similar high places using a theodolite made by Jonathan Sisson (inventor of the telescopic-sighted theodolite) to measure the observed angle between two other prominent locations. The process was repeated from point to point. This image depicts all 24 sheets of Rocque's map. John Rocque and John Pine
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