Flights flown between June 19, 1940 and September 4, 1940 by Woltz Studios, Inc., for the U. S. Dept. of Agriculture, Agricultural Adjustment Administration. Photos numbered SG-1A-10 through SG-6A-37. Scale not given. Stereoscopic coverage. Only indexes are georeferenced.
Calhoun County (Ill.) (W 90°56′--W 90°27′/N 39°24′--N 38°52′)
Illinois State Geological Survey
261 remote-sensing images, 794 megabytes, average file 2.9 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.