since been brought into operation from Marseilles to Malta, from Suez to Aden, and lastly, from Aden to Bombay. On a recent occasion when there was a break-down upon the Indo-European line, the duplex system rendered essential service, and maintained telegraphic communication which would otherwise have been most seriously interfered with.” The invention, we may well believe, “cannot fail to be highly profitable to the proprietors of submarine cables,” or to bring about “before long a material reduction in the cost of messages from places beyond the seas.” * * * * * The next marvel of telegraphy to be described is the transmission of actual facsimiles of writings or drawings. So far as strict sequence of subject-matter is concerned, I ought, perhaps, at this point, to show how duplex telegraphy has been surpassed by a recent invention, enabling three or four or more messages to be simultaneously transmitted telegraphically. But it will be more convenient to consider this wonderful advance after I have described the methods by which facsimiles of handwriting, etc., are transmitted. Hitherto we have considered the action of the electric current in deflecting a magnetic needle to right or left, a method of communication leaving no trace of its transmission. We have now to consider a method at once simpler in principle and affording means whereby a permanent record can be left of each message transmitted. [Illustration: FIG. 6.] If the insulated wire is twisted in the form of a helix or coil round a bar of soft iron, the bar becomes magnetized while the current is passing. If the bar be bent into the horse-shoe form, as in Fig. 6, where A C B represents the bar, _a b c d e f_ the coil of insulated wire, the bar acts as a magnet while the current is passing along the coil, but ceases to do so as soon as the current is interrupted.[30] If, then, we have a telegraphic wire from a distant station in electric connection with the wire _a b c_, the part _e f_ descending to an earth-plate, then, according as the operator at that distant station transmits or stops the current, the iron A C B is magnetized or demagnetized. The part C is commonly replaced by a flat piece of iron, as is supposed to be the case with the temporary magnets shown in Fig. 7, where this flat piece is below the coils.