Gillespie, a husky Texan from El Paso, began his career as a set designer at Paramount in 1922, then joined MGM as an art director when the studio opened in 1925 and stayed for 41 years. In 1936, he replaced James Basevi as special effects chief in charge of miniatures, projection process and mechanical effects. Although he won Oscars in 1944 (Thirty Seconds Over Tokyo) and 1947 (Green Dolphin Street), his most celebrated achievement is the tornado in Wizard.
An oft-told legend maintains that the tornado was created by manipulating a windblown silk stocking through a tabletop set. It was hardly that simple.
Gillespie, a long-time pilot, decided that a tornado funnel was shaped something like the wind socks seen at airports. A miniature of the Kansas farm, scaled at 3/4" to 1', was built on Stage 14. It included cornfields, the house, the barn and fences. Gillespie had a 35' wind sock cast in thin rubber and ordered a steel gantry specially built and suspended from the ceiling. It was rigged to move the full length of the 200' stage. The top of the sock was attached to a small car on the bottom of the gantry. By manipulating the car, the effects experts could make the tornado twist and perform erratic moves. The bottom of the funnel was anchored in a hidden slot that ran the length of the stage.
The first test was a failure because the rubber funnel refused to twist like a tornado. A subsequent version made of muslin whipped around satisfactorily, but it quickly tore loose at the bottom. Another was built, and this time it was reinforced throughout with piano wire. This one twisted and careened wildly. Fuller's earth was fed into the muslin funnel from above, and enough of it escaped through the porous muslin to blur the edges of the sock realistically. The big cloud of dust that surrounds the bottom of a twister was made by blowing Fuller's Earth and compressed air in from underneath. Stormy skies were created with dense smoke fed from the catwalks, while patches of spray-painted cotton attached to 8' x 4' foreground glass plates were placed in front of the camera to mask the top of the tornado and the gantry. Tornado shots were used alone and as process plates to be projected behind Dorothy during her attempt to elude the funnel. The farmhouse, which was about 3' high, was swept aloft on piano wires.
A strange sequence follows in which Dorothy and her house are inside the twister and she sees various things picked up by the cone go hurtling by. The walls of the spout consisted of a circle of painted muslin, 35' in diameter. The camera was placed in the center and spun rapidly while the muslin remained stationary. Then the individual objects that swirl past — men rowing a boat, Hamilton riding her bicycle, Auntie Em in her rocking chair, etc. — were photographed separately and double-printed onto the spinning background. The resulting composite was back-projected outside Dorothy and the window.
The expensive gantry and its perambulating car saw further service in getting the witch's flying monkeys airborne. A dozen monkeys seen in the foreground and in scenes where they harass the heroes were men in costume, all selected because of their slight physiques. They were flown on piano wires and their wings were made to flap by means of small hidden motors. The wires had to be kept taut because kinks caused them to break. Safety nets and pads usually saved the day, although several "monkeys" landed in the hospital.
Model monkeys in various scales, of sizes down to six inches, flying on wires hanging from the tornado gantry, were used in the backgrounds and miniature landscapes. Marcel Delgado, the sculptor and technician who had made the models for The Lost World and King Kong, cast the bodies in rubber over aluminum armatures, with hinges for the wings. Each model required two wires for the bodies and two for flapping the wings. The mass of wires — more than 1,000 altogether — necessitated numerous retakes due to breaks.
Gillespie was also called in to photograph scenes in the poison poppy field, for which it was necessary to have the camera move along the ground surrounded by flowers. He had tracks made of half-tubing and designed a special dolly equipped with half-tube runners that fitted over the tracks. The huge camera moved smoothly and quietly over the well-lubricated tracks.
In one memorable scene, Hamilton's face appears in a large crystal ball. The previously photo-graphed witch was projected from the side onto a mirror set at a 45-degree angle, relaying the image onto a small translucent screen inside the hollow ball.
The giant floating head of the Wizard was front-projected onto heavy clouds of white steam piped in from outside the stage. The front-projection process used today had not been developed at that time, but the close-up registered effectively on the steam in one of the larger projected images that had been attempted in color.
The arrival of Glinda the Good Witch in Munchkinland is a deft bit of fantasy. A silver ball floats like a giant bubble into the scene, looming larger and larger as it moves into the foreground of the set. Upon alighting, it dissolves to reveal Glinda. The actual ball was about 8" in diameter and was not moved while being photographed. Instead, the camera moved to make the ball appear to describe the path it was to follow. The set and actors were photographed separately, and the two films were then printed together as a simple double exposure without protection mattes, which lent the ball an ethereal quality.
Principal photography wrap-ped on March 16, 1939 after five months of production. The final cost was $2,777,000. The Wizard of Oz was highly successful in its New York run at the Capitol — most of the New York critics hated it, but who cared? — and the Hollywood premiere at Grauman's Chinese Theater was lavish. The Harold Arlen/E. Y. Harburg songs, especially "Over the Rainbow," were well-received. The picture's timeless appeal has since made it a cherished tradition in theaters and on television the world over.