Mechanical television or mechanical scan television is an obsolete television system that relies on a mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror drum, to scan the scene and generate the video signal, and a similar mechanical device at the receiver to display the picture.
Mechanical scanning methods were used in the earliest experimental television systems in the 1920s and 1930s.
In the U.S., experimental stations such as W2XAB in New York City began broadcasting mechanical television programs in 1931 but discontinued operations on February 20, 1933, until returning with an all-electronic system in 1939.
The article doesn't do much to give an idea of what mechanical television was really like but you can see something similar in action here.
