Although it can be seen as an extension of the sort of civic pragmatism seen in Oglethorpe's plan for Savannah or William Penn's plan for Philadelphia, the roots of the rational planning movement lie in Britain's Sanitary Movement (1800-1890).[6] During this period, advocates such as Charles Booth and Ebenezer Howard argued for central organized, top-down solutions to the problems of industrializing cities. In keeping with the rising power of industry, the source of planning authority in the Sanitary Movement included both traditional governmental offices and private development corporations. In London and its surrounding suburbs, cooperation between these two entities created a network of new communities clustered around the expanding rail system.[7] Two of the best examples of these communities are Letchworth in Hertfordshire and Hampstead Garden Suburb in Greater London.