How they used miniatures in setting the stage for realistic movies of an airplane and dirigible crash in midair was explained recently by special-effects men. A tiny airplane was released from a 40-foot tower so it would slide down a pair of thin wires rigged up for the purpose, smashing into a model dirigible at the end of the run. On its downward trip the plane struck a switch in its path, thus exploding 12 ounces of flash and black powder and one and one-half gallons of gasoline with which the dirigible was loaded. Flames shot thirty feet into the air and burning fragments from the two models scattered through the air. To give the dirigible the appearance of motion through clouds during the filming of the early scenes before the actual crash, titanium tetrachloride, or “liquid smoke,” was blown in front of the camera, The dirigible model was covered with canvas and painted a silver color.