IN THE CABLE ROOM.

Auckland Star, Volume LV, Issue 168, 17 July 1924, Page 7

IN THE CABLE ROOM.

THE MACHINES AT WORK. HOW MESSAGES ABE HANDLED. ' HUNDREDS EVERY DAT. Only those who understand the true inwardness of the modern cable service can appreciate the high position that the Auckland cable station occupies as one of the most efficient stations eolith of the Line. In the cable room, at the top of the G.P.0., where the messages are received and transmitted, a dozen operators handle hundreds of messages every day, under conditions that appear to the layman admirable for such important work. No distracting sounds from the busy street below disturb the quietness of the place. The presence of the operators busily and quietly attending the instruments is almost unnoticed, and the attention of the visitor who has stepped into the large room for the first time fixes quite naturally upon the eleetric-ally-driven machines that tick unceasingly day and night, like a big clock in a silent room, only much faster, as it they were the only essential features of the place, and "the human element mattered not at all. Yard upon yard of paper tape is seen passing turoujrn metal fingers, immovable as the benches that support the machine, and upon the paper the tiniest glass siphon writes away indefatigably. recording curiouslyshaped outlines with wondrous regularity, and producing what might well . be one continuous row of diminutive mountain peaks. A Fascinating Process. When the observer is reminded that all these puzzling ink marks are caused by a man 1200 miles away in a Eimilar cable room at Sydney, or it may be Suva, working a machine with a keyboard similar to that of a typewriter, the process becomes quite fascinating. Slowly the large coil of paper tape unwinds itself. Occasionally the little siphon, which has its source in an inkbath, stops its strange movements, and traces out a straight dotted line along the very middle of the tape until Sydneygets to -work again with the interrupted message. It strikes you as the perfection of mechanical adjustment and as ■ an example of automatic precision that would be regarded as marvellous, if it were not happening so simply and easily under your very eyes. By now you are beginning to appreciate the efficiency of the cable system; and in the space of an hour or so, when you have been shown how it all works, you flatter yourself unless you are a really clever enough person to know better, that your knowledge of cable work is something like Sam Wellers knowledge of London, extensive and peculiar. Extremely Feeble Signals. A morse alphabet is used in cable work, but instead of actual dots and dashes, positive and negative currents are the result of the transmitting operator's efforts, and these work the fascinating little sipnon recorder, which is] just as important a part of the mechanism of cable telegraphy to-day as it was sixty years ago, when introduced by Lord Kelvin. To prevent frictioli between the siphon and the paper from interfering with the extremely feeble incoming signals, this siphon is kept constantly vibrating. Cables offer a tremendously retarding effect to the signals, and when they arrive at the dietant end they are so attenuated and feeble that, in order to receive them at a satisfactory speed, the cable office must use very sensitive instruments. The normal working speed in Auckland is between thirty and forty words a minute, and may lie increased when necessary to fifty or more. It is, of course, only by amplifying the signals and making them perfectly regular that such a speed can be maintained. The Key to Efficiency. That being so, the instrument which performs the amplifying work gives the key to a cable station's efficiency. Auckland is fortunate in this respect [ in possessing what is known as the I selenium amplifier, an instrument that was introduced ten years ago, and gives our station great possibilities of future development. This amplified, works by means of a mirror that vibrates under the influence of the incoming signals, and reflects the light from an electric bulb on to a selenium cell, composed of a substance that is sensitive enough to magnify the vibrations from one to ten thousand times. Auctually, the Auckland station never requires the signals magnified to that extent, and in ordinary practice works at from two to five hundred. The receiving o? messages is not a matter that calls for a large staff of experts. It is entirely mi automatic process. Once the magnifier has done its highly important work the signals are transmitted to a further machine which turns out the messages on a perforated tapae. All that is then required is to feed the tape into a Creed printer, which prints in Roman characters on a final strip of paper less than half an inch wide. This strip passes through a gumming machine, and is gummed by the receiving operator to the usual telepram form, which is then used for obtaining the required number of copies by means of a copying machine. Sometimes it is necessary for messages to and from Australia to be sent northwards, via Auckland, instead of via Norfolk and Southport, and in that case the perforated tape that reveices the message from Sydney is passed through an automatic transmitter, which re-transmits to Suva. A southbound message can be sent from Suva to Sydney, via, Auckland, in the same way. So important is it to use the cable as much as possible if it is to be run cheaply that in all ordinary times messages are being sent and received simultaneously along the same wire. This depends upon what is known as balancing an "artificial" cable against the real cable. The artificial cable, set up in cabinets about 6ft high, and equipped with a formidable array of adjustment*, contains the electrical equivalent of the 1200 miles of cable that connect Auckland and Sydney. All the electrical conditions of the real cabin must be imitated in the artificial outfit, wherein is located a series of coils of wire corresponding to the cable conductor. "Our great problem,' , said an official of the Pacific Cable Board in discussing this question, "is to get the balance so perfect that our own receiving instrument is unaffected by the currents we are sending out on the same line. The incoming signals arc so feeble that they bear the ratio of something like one to a million, or of the outCTing ones. j. ;-■>;.. ■'-. ..,

~i '-'All cable work aims at pushing -np the working speed of the cable, and we are able to make our receiving instruments so sensitive that the speed could be enormously increased, if only -we conld keep the balance between the artificial and the main cables right. The more sensitive the receiving instruments, the more troublesome are conditions such as varying temperature, which must be compensated for. But we are now beginning to s<'e light through this difficulty, and during tlie past IS months methods have been developed that jiromiso, to make possible higher practicable working speeds, a greater percentage of accuracy, and more economy of service. "These improved methods are being developed here, with the object of applying them as soon as possible to the Ion" cables between Suva ami Vancouver Island, on which higher workin" speeds are badly needed."