TRAINING FILM: Records and explains series of tests in “subversive warfare” on Claiborne Polk Military Railroad. Discusses amount of explosive used, technique of making “gaps” in railroad track to overturn train. Uses filmographic techniques such as slow motion, reverse motion, and freeze frame to show effects of “gaps” and explosives on train and results of experiments. Illustrated arrows point to areas of train considered especially relevant to experiment. Narrator explains each type of explosive and reason for variations.