in a vertical rather than the usual horizontal position. The first 16mm sound-on-film projector was introduced by RCA in 1932; it was named the Junior Portable to avoid confusion with a 35mm portable projector the company had brought out the previous year. In 1935, RCA developed a 16mm sound camera.
Other companies quickly marketed 16mm sound-on-film projectors, beginning with the Filmosound introduced by Bell & Howell in 1933. The following year, DeVry (which had introduced a 16mm silent projector in 1927) and Ampro Corporation of Chicago came out with their first 16mm sound projectors.
One important aspect of 16mm film stock was that it was cellulose acetate rather than nitrate based, as was 35mm film stock prior to 1950, and therefore basically non-flammable. Unlike 35mm nitrate film, 16mm was considered not to be a fire hazard and therefore to be safe for use in the home, classroom, church, and other non-theatrical settings. The selection of the 16mm gauge and the insistence that it should be available only on safety film were two major decisions by Eastman Kodak. The choice of a gauge 16mm in width was quite deliberate in that it precluded the splitting of 35mm film stock. 5
Other early, non-35mm film gauges that preceded 16mm were generally also safety based. In the United States, the earliest was 22mm film, utilizing three rows of pictures with perforations between each, which was developed in 1912 by Thomas A. Edison, Inc., for use on the Edison Home Kinetoscope. However, the equipment, as its name implies, was intended primarily for home use and was not a viable alternative to 35mm in the early non-theatrical market developing in the first two decades of the twentieth century.