Flights flown between July 20, 1941 and September 10, 1941 by Iowa Aerial Surveys, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered RV-1B-3 through RV-4B-20. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Henderson County (Ill.) / W0911100-W0904700 / N0410400-N0403800
Illinois State Geological Survey
231 remote-sensing images, 1.82 gigabytes, average file 8.07 megabytes
Scanned from 9 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.
Mode of access: World Wide Web. System requirements: Plug-in or image viewer, ExpressView Browser plug-in available for download. System requirements for interactive map: Google Chrome best.