MECHANICAL TV was once the only television. Between the world wars, mechanical television debuted on peephole sets built at kitchen tables. Scant years later, manufacturers released consoles with 10 by 14-inch screens. Cinema patrons enjoyed projection television suitable for large audiences. A color mechanical television demonstration took place 25 years before electronic color TV entered homes. Even the ballyhooed 1928 color system wasn't the first color mechanical TV.

MECHANICAL TELEVISION RECEIVERS had no picture tube. Instead, a flickering neon glow tube illuminated the screen. Fifty thousand times a second, a new flicker initiated a different gray value. Behind the screen, a motor spun a scanning disc. Disc apertures distributed gray values over the screen, thereby reproducing pictures. To the viewer, pictures appeared to float on the disc surface. Other mechanical sets substituted a drum or vibrating mirrors for the disc.

TYPICAL DISCS were aluminum or cardboard, and from one to three feet across. Later, engineers succeeded in using disc real estate more efficiently. Next generation mechanical sets incorporated smaller discs with lenses. Some sets required the viewer to manually synchronize pictures. This task actually wasn’t hard. As with channel surfing today, viewers accepted synchronization as part of the entertainment. Later sets responded to sync signals, or incorporated line-synchronous disc motors.

MOST EARLY SCREENS supported pictures the size of a matchbox. Some receivers included magnifiers. These sets achieved postcard-size images. Later mechanical devices made possible screens as large as we have today. Even in 1927, Herbert Ives at AT&T displayed a two by three-foot picture. At first, TV pictures appeared coarse-grained. Due to government regulations, pictures from early equipment consisted of some 24 to 60 lines. Picture detail topped out at less than three percent of what we enjoy today. Yet even these low-definition pictures could display recognizable faces. Later mechanical television devices yielded resolution exceeding the specifications of today’s television. Manufacturers such as Western, Daven, Pilot and Peck sold television kits and sets. (See how it works.)