"# 560 Gravel screening plant under construction. View taken from the water clarifier tank. November 3rd, 1931.
# 640 Same as #560. December 1st, 1931.
# 562 Sixty-foot screening towers under construction. November 3rd, 1931.
# 636 Same as #562. December 1st, 1931."
black and white photographs 4 x 5.3 in. or 8 x 4.8 in. paper background 10 x 13.5 in.
Archived TIFF images were scanned by Kathleen Broeder at 400 dpi with an Epson Expression 10000XL scanner. Digital images were reformatted in Photoshop. JPG and PDF files were then created for general use.