SUBMARINE CABLES.

WORKING.

The working and maintenance of the existing telegraph lines employ a vast number of people taken all together; but it is surprising how few hands are necessary for the working of any single line or system. This is especially so in the case of submarine cables, where, when the cable continues sound, it is not necessary to support a staff for surveillance and repairs. Half-a-dozen stations several hundred miles apart, and half-a-dozen men at each, are sufficient to carry the news from one end of a continent to the other.

Without enumerating the telegraph systems that now exist, it may suffice to say that the British Isles are connected by submarine cables with nearly every quarter of the globe, and that their number is still increasing.

A telegraph station abroad, no matter in what Company or country, presents nearly the same characteristics wherever found. The more remote the place, the more primitive may be the arrangements; but the work is the same, the men are about the same, and the instruments almost invariably so. There is the superintendent; and under him the clerk in charge, his right-hand man, who oversees the clerks or operators at their work of sending and receiving messages. Then, besides these, and partly independent of them, there is the electrician, a member of the scientific as distinguished from the operating staff of the Company, whose duties are to take periodical tests of the cable and land-lines, to report on their condition, and to keep the instruments in proper working order. Under all these, there is generally the messenger and battery-man, who may be called the stoker of the electrical engine, and who, besides, does the odd work of the establishment.

The station itself generally consists of the superintendent's office or bureau; the instrument-room, where the messages are sent and received; the battery-room, generally under ground; and the sleeping-quarters of the clerks. Occasionally the electrician and clerk in charge have separate working-rooms; and a smoking-room, with perhaps a billiard-table and home newspapers, are added for the convenience of all. Life passes quietly and uneventfully at these stations, except when something goes wrong with the instruments or the cable, and then the electrician has his period of anxiety and trouble; while the operators, on the other hand, find their occupation at a temporary standstill.

To understand the working of a submarine cable and the actual process of sending a message, it is necessary to figure in imagination the several parts of the electric circuit, made up of the battery, the instruments, the cable, and the earth itself; and to remember that for a current of electricity to flow through any part of the circuit it is necessary that the whole circuit should be complete. Starting then from the battery, which is the source of the electric current, we have the cable joined to it by means of a key or sending instrument, which by the working of a short up-and-down lever can connect or disconnect the conductor of the cable to a particular pole of the battery, the other pole of the battery being the while connected to the earth. The cable then takes us to the distant station. Here the conductor is connected to the receiving instrument, or instrument for making the signals indicating the message, and through the receiving instrument it is connected to the earth. The electric circuit is thus rendered complete. The current passes from one pole of the battery by means of the key into the cable, through the cable to the instrument at the other end, and thence to the earth; and inasmuch as the other pole of the battery is at the same time connected to the earth at the first station, the conducting circuit is complete, for the earth, no matter what the intervening distance be, acts as an indispensable part of the circuit.

We have thus the two stations connected by a cable. At the station sending the message there is the battery, from which the current proceeds; the sending instrument, for letting the current into the cable, or stopping it; and the 'earth-plate,' or metal connection between one pole of the battery and the earth. At the station receiving the message there is the receiving instrument, and again the earth-plate, connecting the earth into circuit. These separate parts of the circuit, as we have already said, must be 'connected up,' as it is termed, so as to provide a complete conducting channel for the current to flow in from one pole of the battery to the distant place and back again (or virtually so) through the earth. Only at one place can the circuit be interrupted and the current consequently stopped—that is, at the key of the sending instrument. Here then the sending clerk sits, and by manipulating the lever of this key he 'makes and breaks' the circuit at will, and thereby controls the current. The regulated making and breaking of this connection is the basis of telegraphing, whether by submarine cable or by the ordinary land lines. Accordingly as the clerk maintains the circuit for a longer or a shorter time, so will the current give longer or shorter indications on the receiving instrument at the distant station: or again, according as the opposite poles of the battery are applied to the cable by the key, and the direction of the current consequently reversed in the cable, so will the indicated signals on the receiving instrument be of opposite kind. From the elementary short and long signals, or right and left signals, so obtained on the receiving instrument, a code of letters and words may be built up, and intelligible messages transmitted. The Morse Code is that universally adopted, and for the further information of our readers we here append it as it is usually written: