ture of the earth's surface; besides being nearly useless as a signal at night, and totally so in fogs or cloudy weather. The only agent that will serve our purpose is Electricity. It is far swifter than sound or light. It is not afraid of the dark, and it can travel in all weathers. It can outrival even the goblin messenger in the old ballad, of whom we are told— "And when he came to broken bridge, He bent his bow and swam; And when he came to grass growing, Set down his feet and ran. And when he came to Greenwood Hall, Would neither knock nor call; But set his bent bow to his breast, The highway for this subtle spirit—which, together with the generating and propelling apparatus at the one end, and the receiving and recording instruments at the other, constitutes the Electric Telegraph—is in one sense the lineal descendant of the older methods of speaking and writing to a distance. But its purely scientific parents are the Compass-needle and the Electrical Machine. As the guide of Columbus to the New World, the magnetic needle was the precursor and pioneer of the Telegraph. Silently, and as with finger on its lips, it led him across the waste of waters. And the time has come when, as an integrant of the Telegraph, it has removed its finger and broken silence, so that now the inhabitants of the old and the new hemispheres exchange affectionate greetings. The quivering magnetic needle which lies in the coil of the galvanometer is the tongue of the electric Telegraph, and engineers talk of it as speaking. The magnet, however, did not, till 1820, directly aid the Telegraph. What, then, of the other parent? We strike sharply, in beginning, on a definite date, 1600, when Gilbert of Colchester introduced the new word, and the all but new science, Electricity. The science, thus recognised and titled, made rapid progress. The lump of amber was changed for a fragment of sulphur, which soon grew into a globe, and was by-and-by replaced by a glass sphere, a cylinder, or a plate, whirled rapidly, and constituting an Electrical Machine. By the beginning of the eighteenth century, men knew well how to produce electricity. And soon afterwards they discovered that some bodies conduct, and others do not conduct it; so that they were in possession of the essential halves of an electrical highway, namely, conductors free through half their length, and insulated through the other half by non-conductors. In 1745, the Leyden Jar was stumbled on. It was literally an electrical condenser, and did as much to enhance the power of the friction-machine, as Watt's steam-condenser did to enlarge that of the steam-engine. Provided with the Leyden Jar, the next two important telegraphic discoveries were speedily made: the one that electricity traverses a metallic wire with inconceivable rapidity; the other that it travels with equal celerity through earth or water. Here, then, were two-thirds of the Telegraph supplied; the message-sender was there, and so was the message-carrier. Why was not a message-receiver also provided? The fault lay with the sender. Friction-electricity is so brief in duration, and so intense and impetuous, that it cannot be induced to take a long journey. The best conductors in their best state of insulation are unwelcome to it. If there is the least obstacle in any part of its path, it turns off, as it were, at a side-station, and returns by the shortest route with its message undelivered. Owing to this hindrance, Electrical Telegraphy remained at a stand-still for half a century. But, in 1800, the Voltaic Battery, already some years in use, was ascertained to produce a continuous stream of electricity, far less impetuous and reluctant to travel than the electricity of the friction-machine. We had to wait, however, twenty years longer, till two famous additional discoveries were made: the one that the electrical current deflects the compassneedle; the other that the electric current develops magnetism. Our earliest Electric Telegraph was electro-magnetic; and to this day the majority of Telegraphs employ electricity to produce signals, either by moving a permanent magnet, or by making a temporary one. The land Telegraph was now in essentials complete; but a subaqueous Telegraph was still impossible for want of a good insulator. Great historical importance, accordingly, attaches to the importation, in 1843, of gutta-percha, which, from its powerful insulating properties, has rendered it possible to lay telegraph wires across the beds of the mightiest oceans. The early attempts to lay submarine cables were attended with much difficulty and many failures. The first of these, laid in 1850 between Dover and Calais, continued to act only for a day; and that greatest achievement of electric engineering, the bringing together of the Old and New Worlds, was not successfully accomplished till three cables had been laid across the Atlantic. The first Atlantic cable was laid in 1858, but ceased to convey messages after a month. In 1865 a second was laid and lost. In 1866, however, telegraphic communication was permanently established by the successful laying of a third cable; and since then nearly all the most important parts of the world have been brought into telegraphic communication with each other, and the feat of putting an electric girdle round the globe has been virtually consummated. The existing lines include many hundred thousand miles of wire. The batteries amount to thousands, and demand a lake or river of sulphuric acid to excite them. The magnets are not less numerous than the batteries; and of lesser instruments the name is legion. The arts involved, who can patiently enumerate? Consider what felling of forests there must have been; what quarrying and dressing of metallic ores; what smelting and working of metals; what tapping of gutta-percha trees; what digging of coal and sulphur, and blazing of brimstone to make oil of vitriol; what loading of ships and guiding them safe across the seas of the world! —and all this but the preparation of the raw material! Add its elaboration and application !—the navvy work of laying lines, spinning cables, erecting posts, and otherwise fitting together the ruder components of the Telegraph; and the multiplied artistic skill in constructing batteries, dials, alarums, and other refined apparatus required upon the line! Lastly, consider how vast is the genius which our Telegraph represents;-all that the world knows of electricity since first there was a thunderstorm; all that the world knows of magnetism since first a loadstone was seen to lift iron dust; all that the world knows of a science whose name, Chemistry, has left its first meaning in the forgotten darkness of antiquity! Let us wish all success to the Telegraph everywhere. The best interests of the world are bound up in its progress, and its mission is emphatically one of peace. It does not speak swiftly merely, but softly; and it offers men a common speech in which all mankind can converse together. Compiled. SPECIMENS OF THE POETRY OF THE EIGHTEENTH CENTURY. (Chronologically arranged.) How poor, how rich, how abject, how august, EDWARD YOUNG (b. 1681). BUT most by numbers judge a poet's song; And smooth or rough with them is right or wrong; Who haunt Parnassus but to please the ear, Not mend their minds; as some to church repair, While expletives their feeble aid do join, That like a wounded snake drags its slow length along. ALEXANDER POPE (b. 1688). OH! who can speak the vigorous joys of health, Yet what but high-strung health this dancing pleasance breeds ? I care not, Fortune, what you me deny : You cannot rob me of free Nature's grace; You cannot shut the windows of the sky, Through which Aurora shows her brightening face; The woods and lawns, by living stream, at eve: JAMES THOMSON (b. 1699). GAY hope is theirs by fancy fed, And lively cheer, of vigour born; |