DCNR volunteer John Chos operates a late 19th or early 20th century Bessemer gas engine at the Muddy Creek Oil Well Living History program Saturday at Moraine State Park. The oil operation was active from the late 1800s to the 1960s. Visitors can see monthly demonstrations of one of the original engines that once alternated pumping of 19 to 29 nearby oil wells. The wells and a small museum are located on the southeastern edge of the park. Volunteers will be staffing the site for more living history programs Aug. 10, Sept. 14 and Oct. 12.