Sec (section) A. D. T. (Daily Telegraph) Fm (from) Berri, Antivari.
Then follow the letters G. Q., signifying fresh line.
They hd (had) bn (been) seen advancing in t (the) distance and wr (were) recognised by thr (their) usual uniform wh (which) consists o (of) a white fez.
Finally double dots indicating full stop.
A good Morse operator can maintain a speed of about thirty words a minute, but this is far too slow for certain kinds of telegraphic work, such as the transmission of press news, and for such work the Wheatstone automatic transmitter is used. First of all the messages are punched on a paper ribbon. This is done by passing the ribbon from right to left by clockwork through a punching machine which is provided with three keys, one for dots, one for dashes, and the other for spaces. If the left-hand key is pressed, two holes opposite to one another are made, representing a dot; and if the right-hand key is pressed, two diagonal holes are punched, representing a dash. In [Fig. 29], which shows a piece of ribbon punched in this way, a third line of holes will be noticed between the outside holes representing the dots and dashes. These holes are for the purpose of guiding the paper ribbon steadily along through the transmitting machine. The punched ribbon is then drawn by clockwork through a Wheatstone transmitter. In this machine two oscillating needles, connected with one pole of a battery, are placed below the moving ribbon. Each time a hole passes, these needles make contact with a piece of metal connected with the other pole of the battery, thus making and breaking the circuit with much greater rapidity than is possible with the Morse key. At the receiving station the messages are recorded by a form of Morse inker, coming out in dots and dashes as though sent by hand. Below the punched ribbon in [Fig. 29] is shown the corresponding arrangement of dots and dashes. The same punched ribbon may be used repeatedly when the message has to be sent on a number of different lines. The Wheatstone automatic machine is capable of transmitting at the rate of from 250 to 400 words a minute. [Fig. 29] is a fragment of a Daily Telegraph Balkan War special, as transmitted to the Yorkshire Post over the latter’s private wire from London to Leeds. In the translation it will be seen that many common words are abbreviated.
One weak point of telegraphy with Wheatstone instruments is that the messages are received in Morse code, and have to be translated. During recent years telegraphs have been invented which actually produce their messages in ordinary written or printed characters. A very ingenious instrument is the Hughes printing telegraph, which turns out messages in typewritten form. Its mechanism is too complicated to be described here, but in general it consists of a transmitter having a keyboard something like that of a typewriter, by means of which currents of electricity are made to press a sheet of paper at the right instant against a revolving type-wheel bearing the various characters. This telegraph has been modified and brought to considerable perfection, and in one form or another it is used in European countries and in the United States.
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.
The tape prepared in this way is passed through a Wheatstone transmitter, and long or short currents, according to the arrangement of the perforations, are sent out along the telegraph line. At the receiving station these signals operate a receiving perforator. This machine produces another perforated tape, which is an exact copy of the tape at the sending station, and it turns out this duplicate tape at the rate of from 150 to 200 words a minute. There are two forms of this receiving perforator, one worked entirely by electricity, and the other by a combination of electricity and compressed air, both forms serving the same purpose. The duplicate tape is then passed through an automatic printer, which reproduces the message in large Roman characters on a paper tape. The printer works at a speed of from 80 to about 100 words a minute, and the printed tape is pasted on a telegraphic form by a semi-automatic process, and the message is then ready for delivery. [Plate XI]. shows a specimen of the tape from the receiving perforator, and the corresponding translation as turned out by the printer. This message formed part of a leading article in the Daily Mail. Some idea of the wonderful capabilities of the Creed system may be gained from the fact that by means of it practically the whole contents of the Daily Mail are telegraphed every night from London to Manchester and Paris, for publication next morning.
One of the most remarkable features about present-day telegraphy is the ease with which two or more messages can be sent simultaneously over one line. Duplex telegraphy, or the simultaneous transmission of two separate messages in opposite directions over one wire, is now practised on almost every line of any importance. At first sight duplex telegraphy seems to be an impossibility, for if we have two stations, one at each end of a single wire, and each station fitted with a transmitter and a receiver, it appears as if each transmitter would affect not only the receiver at the opposite end of the wire, but also the receiver at its own end, thus causing hopeless confusion when both transmitters were in use at the same time. This actually would be the case with ordinary telegraphic methods, but by the use of a special arrangement all confusion in working is avoided.