Visualising past geographies: the use of animated cartograms to represent long-run demographic change in Britain

Some social processes are directly experienced, but the effects of demographic change are often slow and imperceptible. Further, in a country such as the UK there is much geographical variation and many of the extremes are found among urban populations concentrated into small areas which barely figure on conventional maps. Cartograms -- maps in which areas are made proportional to some other variable such as population -- help solve this second problem while animation deals with the first. The paper presents early results of research based on combining a large historical GIS for Britain, constructed at QMW and containing both a large volume of census and vital registration data from 1851 onwards and the CHANGING boundaries of the various reporting units, and an algorithm developed by Daniel Dorling (Bristol) for the automatic computation of cartograms. Each district is represented by a circle whose changing radius shows population growth or decline; processes contributing to that growth, such as net migration, are shown by changing shading. The animated cartograms we create cannot be conventionally published but can be distributed on CD or viewed over the World-Wide Web.