Transmission and Reception of Photoradiograms

This paper carries the art of electric picture transmission from its inception, over 80 years ago, to the results of present-day development. It is pointed out that the seemingly rapid strides that have been made in the art during the last 10 years of its 83-year existence may be attributed to the larger storehouse of electrical and mechanical contrivances from which modern photo-transmission engineers may draw. Picture transmission is not, as many think, a modern art. It is as old as the communication art itself and this paper carries us through the work, ancient and modern, of photo-transmission engineers, commencing with that of Alexander Bain in 1842. A Denison facsimile of telegraph tape, taken in 1901, is shown, together with examples of the work of Korn taken in 1922; that of Bart-Lane in 1922; Belin, 1924; Ferree, 1924; Jenkins, 1924; and results of the A. T. & T. system in 1925. The basic elements of all picture transmission systems are shown to consist of synchronously covering a surface, point-by-point, at both transmitter and receiver, and electrically identifying point values at the receiver so that any integral section of the received copy will have the same relative tonal value as the identical integral section on the transmitting surface.