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Show LAYING THE FIRST CABLE. Protected with Half an Inch of Gutts Percha and Sunk with Lead. In modern cables the core is always pro-j tected first by a serving of hemp or jute' and then by an outer sheath of . soft, steel wires, which are relied on to fur-( nish the mechanical strength which tha cable must have In order that i& may stand the pulling about which it reu ccives in laying and repairing. But the .SVaf-A urday Review says that in that pioneertrral, there was no idea of a protecting sheath th naked core was to be laid in the channel to( form the first telegraph between Englandrztnd France. There was but a single wire of ep- per inside (nowadays there is always Jr strand of several wires twisted together! and this was covered with gutta percha 6cv thickly as to bring the diameter to hali ajj inch. The covered wire was wound on an great reel on the deck of a steam tug, trai Dover harbor, and after a numbert oft preliminary trips the line waa laUf on the 23d of August, 1S50. Lead sinkers were attached at every hundred jardV to carry the cable to ttw bottom, for, . in tbei absence of any heavy sheathing, its speci&c gravity scarcely exceeded tliat of sea watelj The attempt was at once made to open ocina'-, munication, but though signals teemed tal pass, nothing could be made of them, and i Mr. Smith records that the operators at-seb. end were regretfully forced to the coiictuv' sion that those at the other end babeoo.! lunching, not wisely, but too welL 25erV day matters were worse; no signals wool pass at all. The cable was broken, and ended this first attempt at submarine teieU graphy. The signals of the first day had beeaui intelligible, not because of any breach f continuity on the part of the cable, or f$CH ure in temperance on the part of Its guard ians, but simply in consequence of electros., tatic induction, the influence of which, iij retarding the electrics pulses, was not then understood. It was to overcome the difficulty diffi-culty caused by induction that Sir William Thomson, eight years later, invested hj mirror galvanometer, thereby making it practicable to speak at a reasonable pace-even pace-even through lines aa long as the thaft cross the Atlantic. - |