In the Pollak-Virag system of telegraphy the action of light upon sensitized photographic paper is utilized. An operator punches special groupings of holes on a paper ribbon about 1 inch wide, by means of a perforating machine resembling a typewriter, and the ribbon is then passed through a machine which transmits by brush contacts. The receiver consists of a very small mirror connected to two vibrating diaphragms, which control its movements according to the currents received, one diaphragm moving the mirror in a vertical direction, and the other in a horizontal direction. The mirror reflects a ray of light on to photographic bromide paper in the form of a moving band about 3 inches in width, and the combined action of the two diaphragms makes the mirror move so that the ray of light traces out the messages in ordinary alphabetical characters. As it moves forward after being acted upon by the light, the paper is automatically developed and fixed, and then passed through drying rollers. Although the writing is rather imperfect in formation it is quite legible enough for most messages, but trouble occasionally occurs with messages containing figures, owing to confusion arising from the similarity of the figures, 3, 5, and 8. The whole process is carried out with such rapidity that 40,000 or even more words can be transmitted easily in an hour. One of the most remarkable of present-day telegraphs is the Creed high-speed automatic printing telegraph. This has been devised to do away with hand working as far as possible, and to substitute quicker and more accurate automatic methods. In this system a perforated paper tape is produced by a keyboard perforator at the sending station. This tape is just ordinary Wheatstone tape, its perforations representing in the Morse code the message to be transmitted; and the main advantage of the Creed perforator over the three-key punching machine already described lies in the ease and speed with which it can be worked. The keyboard contains a separate key for each letter or signal of the Morse code, and the pressing of any key brings into operation certain punches which make the perforations corresponding to that particular letter. The perforator can be worked by any one who understands how to use an ordinary typewriter, and a speed of about 60 words a minute can be maintained by a fairly skilful operator. If desired a number of tapes may be perforated at the same time.