View of old cast iron gears and new steel gears and cast iron housing, Detroit water supply system. Printed on front: "Old cast iron gears; new steel gears and cast iron housing. City of Detroit. Department of Water Supply. Installation of 24" gear housings. Distribution system. Continental & Essex Ave. Contract PS-186. PWA docket 7361. Item G. Ray D. Baker, Contracting & Engineering Co. No. 3. Date: July 1, 1935."