Matching pair of charts showing the extent of the survey. Complete with the original 36-page report by J.R. Poinsett and Lieut. Albert. First chart measures 31.2 x 7.3" and the second 37.5 x 7.4". Survey extends from French Creek and Franklin to Mahoning Creek (No. 1) and continues on to Pittsburgh on No. 2. Rarely seen pair of maps complete with report.