App. 66, 137 N.E. 579 (Ind. 1922); Spies v. DeMayo, 396 Ill. 255, 72 N.E.2d 316 (1947); R. Hemingway, The Law of Oil and Gas ?? 7.10 (1971). ??10 However, casing in wells, derricks, engines and other machinery placed upon the land by the lessee for developing and operating the land for oil and gas purposes are considered trade fixtures.