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Cassini Old Series (1805-1874)

Cassini Old Series (1805-1874) - sample image

Georeferenced high quality reproduction of OS one-Inch ('Old series') maps dating from 1816-1830, reprojected to match OS Landranger series.

The mapping used the Cassini projection, which was to be the projection most commonly employed by the Ordnance Survey until the 1940s. Due to the projection differences used across GB and the lower degree of accuracy thanks to the technology of the time, customers should expect that data will not always match up with contemporary mapping.

It soon became clear that the policy of using a meridian of 3ºW for the western maps and Greenwich's 0º for the eastern ones would lead to a convergence between the sheets that would increase as the survey progressed north. Map sheets in central England became progressively more trapezoid in shape as they progress north, rather than the usual rectangular shape. It was eventually decided to use new meridian through the origin of Delamere Forest in Cheshire. This convergence, and the new base line (the Preston to Hull line), which was perpendicular to the meridian through Delamere, can be seen on the Old Series index map.

Product details

Product: Cassini Old Series (1805-1874)
Author: Cassini Maps
Scale: 1:50000
Datum: OSGB36
Projection: Transverse Mercator
Spheroid:
Licence:view pdf