Hey, just look at this nifty invention from Mullard in 1951. Using flying spot scanning, the time bases of two cathode ray tubes, one a transmitter and the other a receiver are synchronised. In the transmitter, a raster is projected onto a glass overscreen. In the absence of any writing on the overscreen, the light beam passes through the glass. If however, a mark is made on the overscreen then some light is reflected then detected by a photocell. The electrical currents produced in this way are amplified and used to modulate the beam in the receiving cathode ray tube which results in a facsimile reproduction of the original work.
This was hailed as a very clever piece of kit in 1951 - no PDA, tablets or iPAD then you know and these pieces of kit were so big that no-one could steal them easily....... unlike a PDA, tablet or iPAD!!!!!!
These handy devices were used by the BBC and here we see Arthur Ferrier, the cartoonist drawing one of his charcters on the Telescribe operating on the Mullard stand at a 1951 Radio Show.
I quite like Arthur as he was an Analytical Chemist like me and then turned to cartoon drawing as a way to supplement his meagre earnings as a scientist. He made it big in 1930 when he produced a weekly strip glamour cartoon called "Film Fannie"..... The mind boggles............