View of an advertising card for the American Blower Company, depicting a disc fan blower. Printed on front: "American Blower Company, heating and ventilating engineers. Manufacturers of steel plate blowers, ventilating fans, exhaust fans, engines, lumber dry kilns, brick dryers, etc., etc. The A.B.C. fan system of heating and ventilation for schools, churches, factories and all public buildings. The A.B.C. patent hot blast apparatus, Detroit, Michigan. New York, London." Photograph of unidentified cornerstone laying in background.