Flights flown between June 14, 1938 and July 25, 1938 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered BHK-1-3 through BHK-3-12. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Williamson County (Ill.) (W 89°09′--W 88°42′/N 37°52′--N 37°36′)
Illinois State Geological Survey
235 remote-sensing images, 1.72 gigabytes, average file 7.48 megabytes
Scanned from 7 x 9 contact prints (nominal scale ca. 1:20,000) on Crosfield Celsis 6200 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.