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Fig. 191. Possible Route of a Salesman Traveling by Automobile to the Small Towns Southwest of Philadelphia
This illustration was photographed full size from one of the U. S. Geological Survey maps having a scale of about one inch to the mile. A ruler was included in the photograph to show inches. On the left half, glass-head map pins; on the right, cloth-covered map tacks. A red string between pins shows the route
