Flights flown between October 25, 1938 and May 10, 1939 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BGF-1-3 through BGF-4-9. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Coles County (Ill.) (W 88°28′--W 87°58′/N 39°41′--N 39°22′)
Illinois State Geological Survey
325 remote-sensing images, 991 megabytes, average file 3.0 megabytes
Scanned from 7 x 9 contact prints (nominal scale ca. 1:20,000) on Crosfield 646IE drum scanning system at 750 dpi. Quality assurance target not published but available by contacting the Illinois State Library Map Dept. MrSID files compressed at a target ratio of 12:1. Uncompressed TIFF images on cd available from the Illinois State Library Map Dept.