Is there another? The man on the left is Lyman Knapp of Blackwell, Oklahoma. That's his 10 HP vertical boiler, chain-driven Canton Monitor built around 1890 at Canton, Ohio, by Cornelius Aultman Co., later to become part of Aultman & Taylor Co. Lyle Hoffmaster from Bucyrus, Ohio, owns the only other Canton Monitor known to exist. Of course they'd like to hear if there's a third. The engine was fired up at the Pawnee steam show.