An early television camera. An arc lamp is situated at the right. A system of lenses and a rotating, perforated disc produce a scanning point of light on the subject. The three objects facing the girl are selenium photoelectric cells.

Watching Television in 1928. The rotating perforated disc has 50 holes spirally placed, and rotates 18 times a second. The neon tube behind the disc has a large cathode plate, shown below.