Photograph entitled 'One of the original photo-electric cells used for the Baird 30 line spot-light transmitter'

Photograph of piece of equipment (photograph on left of this page) with caption 'One of the original photo-electric cells used for the Baird 30 line spot-light transmitter'. From a collection of photographs illustrating the early experimental television work of John Logie Baird, 1924-1938.