Title supplied by cataloger based on information from sheet labels. Images are photoreductions of mosaics created from original aerial photographs. Designating symbol TH; form of individual image numbering: TH-1-[number], TH-3-[number], TH-4-[number], TH-5-[number], or TH-14-[number]."Date of completion 08-05-37" Flown by Gatschet Aerial Surveys, Des Moines, Iowa."Approximate scale, 1:20,000" [refers to individual images from which mosaic was made]. Library's copy 2 consists of photographic negatives (4 x 5 in.) corresponding to each of the images in its copy 1. Contact the Map Collection at The University of Iowa Libraries: http://www.lib.uiowa.edu/maps/contact/