Designated A Historic Landmark Of Agricultural Engineering The Massey-Harris No. 20 was the First Commercially- Successful Self-Propelled Combine Used to Harvest Small Grains Under a Wide Variety of Conditions, World-Wide. Engineered By Thomas Carroll, Chief Engineer, Aided by Robert Ashton and Albert Luke, Principal Assistants, it was First Marketed in 1938 by the Massey-Harris Company. This Combine Opened a New Era an Farm Mechanization and Revolutionized the Grain Harvesting Process. Forty-Four Years Later, This Same Harvesting Principle Continues to be Used Throughout the World. Dedicated by the American Society Of Agricultural Engineers April, 1982.