heroes of the telegraph-第3节
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auxiliary device by which a current too feeble to indicate the signals could call into play a local battery strong enough to make them。 Davy was in a fair way of becoming one of the fathers of the working telegraph； when his private affairs obliged him to emigrate to Australia； and leave the course open to Cooke and Wheatstone。
CHAPTER II。
CHARLES WHEATSTONE。
The electric telegraph； like the steam…engine and the railway； was a gradual development due to the experiments and devices of a long train of thinkers。 In such a case he who crowns the work； making it serviceable to his fellow…men； not only wins the pecuniary prize； but is likely to be hailed and celebrated as the chief； if not the sole inventor； although in a scientific sense the improvement he has made is perhaps less than that of some ingenious and forgotten forerunner。 He who advances the work from the phase of a promising idea； to that of a common boon； is entitled to our gratitude。 But in honouring the keystone of the arch； as it were； let us acknowledge the substructure on which it rests； and keep in mind the entire bridge。 Justice at least is due to those who have laboured without reward。
Sir William Fothergill Cooke and Sir Charles Wheatstone were the first to bring the electric telegraph into daily use。 But we have selected Wheatstone as our hero； because he was eminent as a man of science； and chiefly instrumental in perfecting the apparatus。 As James Watt is identified with the steam…engine； and George Stephenson with the railway； so is Wheatstone with the telegraph。
Charles Wheatstone was born near Gloucester； in February； 1802。 His father was a music…seller in the town； who； four years later； removed to 128； Pall Mall； London； and became a teacher of the flute。 He used to say； with not a little pride； that he had been engaged in assisting at the musical education of the Princess Charlotte。 Charles； the second son； went to a village school； near Gloucester； and afterwards to several institutions in London。 One of them was in Kennington； and kept by a Mrs。 Castlemaine； who was astonished at his rapid progress。 From another he ran away； but was captured at Windsor； not far from the theatre of his practical telegraph。 As a boy he was very shy and sensitive； liking well to retire into an attic； without any other company than his own thoughts。 When he was about fourteen years old he was apprenticed to his uncle and namesake； a maker and seller of musical instruments； at 436； Strand； London； but he showed little taste for handicraft or business； and loved better to study books。 His father encouraged him in this； and finally took him out of the uncle's charge。
At the age of fifteen； Wheatstone translated French poetry； and wrote two songs； one of which was given to his uncle； who published it without knowing it as his nephew's composition。 Some lines of his on the lyre became the motto of an engraving by Bartolozzi。 Small for his age； but with a fine brow； and intelligent blue eyes； he often visited an old book…stall in the vicinity of Pall Mall； which was then a dilapidated and unpaved thoroughfare。 Most of his pocket…money was spent in purchasing the books which had taken his fancy； whether fairy tales； history； or science。 One day； to the surprise of the bookseller； he coveted a volume on the discoveries of Volta in electricity； but not having the price； he saved his pennies and secured the volume。 It was written in French； and so he was obliged to save again； till he could buy a dictionary。 Then he began to read the volume； and； with the help of his elder brother； William； to repeat the experiments described in it； with a home…made battery； in the scullery behind his father's house。 In constructing the battery the boy philosophers ran short of money to procure the requisite copper…plates。 They had only a few copper coins left。 A happy thought occurred to Charles； who was the leading spirit in these researches； 'We must use the pennies themselves；' said he； and the battery was soon complete。
In September； 1821； Wheatstone brought himself into public notice by exhibiting the 'Enchanted Lyre；' or 'Aconcryptophone；' at a music…shop at Pall Mall and in the Adelaide Gallery。 It consisted of a mimic lyre hung from the ceiling by a cord； and emitting the strains of several instrumentsthe piano； harp； and dulcimer。 In reality it was a mere sounding box； and the cord was a steel rod that conveyed the vibrations of the music from the several instruments which were played out of sight and ear…shot。 At this period Wheatstone made numerous experiments on sound and its transmission。 Some of his results are preserved in Thomson's ANNALS OF PHILOSOPHY for 1823。 He recognised that sound is propagated by waves or oscillations of the atmosphere； as light by undulations of the luminiferous ether。 Water； and solid bodies； such as glass； or metal； or sonorous wood； convey the modulations with high velocity； and he conceived the plan of transmitting sound…signals； music； or speech to long distances by this means。 He estimated that sound would travel 200 miles a second through solid rods； and proposed to telegraph from London to Edinburgh in this way。 He even called his arrangement a 'telephone。' ＇Robert Hooke； in his MICROGRAPHIA； published in 1667； writes： 'I can assure the reader that I have； by the help of a distended wire； propagated the sound to a very considerable distance in an instant； or with as seemingly quick a motion as that of light。' Nor was it essential the wire should be straight； it might be bent into angles。 This property is the basis of the mechanical or lover's telephone； said to have been known to the Chinese many centuries ago。 Hooke also considered the possibility of finding a way to quicken our powers of hearing。＇ A writer in the REPOSITORY OF ARTS for September 1； 1821； in referring to the 'Enchanted Lyre；' beholds the prospect of an opera being performed at the King's Theatre； and enjoyed at the Hanover Square Rooms； or even at the Horns Tavern； Kennington。 The vibrations are to travel through underground conductors； like to gas in pipes。 'And if music be capable of being thus conducted；' he observes；'perhaps the words of speech may be susceptible of the same means of propagation。 The eloquence of counsel； the debates of Parliament； instead of being read the next day only；But we shall lose ourselves in the pursuit of this curious subject。'
Besides transmitting sounds to a distance； Wheatstone devised a simple instrument for augmenting feeble sounds； to which he gave the name of 'Microphone。' It consisted of two slender rods； which conveyed the mechanical vibrations to both ears； and is quite different from the electrical microphone of Professor Hughes。
In 1823； his uncle； the musical instrument maker； died； and Wheatstone； with his elder brother； William； took over the business。 Charles had no great liking for the commercial part； but his ingenuity found a vent in making improvements on the existing instruments； and in devising philosophical toys。 At the end of six years he retired from the undertaking。
In 1827； Wheatstone introduced his 'kaleidoscope；' a device for rendering the vibrations of a sounding body apparent to the eye。 It consists of a metal rod； carrying at its end a silvered bead； which reflects a 'spot' of light。 As the rod vibrates the spot is seen to describe complicated figures in the air； like a spark whirled about in the darkness。 His photometer was probably suggested by this appliance。 It enables two lights to be compared by the relative brightness of their reflections in a silvered bead； which describes a narrow ellipse； so as to draw the spots into parallel lines。
In 1828； Wheatstone improved the German wind instrument； called the MUND HARMONICA； till it became the popular concertina； patented on June 19； 1829 The portable harmonium is another of his inventions； which gained a prize medal at the Great Exhibition of 1851。 He also improved the speaking machine of De Kempelen； and endorsed the opinion of Sir David Brewster； that before the end of this century a singing and talking apparatus would be among the conquests of science。
In 1834； Wheatstone； who had won a name for himself； was appointed to the Chair of Experimental Physics in King's College； London； But his first course of lectures on Sound were a complete failure； owing to an invincible repugnance to public speaking； and a distrust of his powers in that direction。 In the rostrum he was tongue…tied and incapable； sometimes turning his back on the audience and mumbling to the diagrams on the wall。 In the laboratory he felt himself at home； and ever after confined his duties mostly to demonstration。
He achieved renown by a great experimentthe measurement of the velocity of electricity in a wire。 His method was beautiful and ingenious。 He cut the wire at the middle； to form a gap which a spark might leap across； and connected its ends to the poles of a Leyden jar filled with electricity。 Three sparks were thus produced； one at either end of the wire； and another at the middle。 He mounted a tiny mirror on the works of a watch； so that it revolved at a high velocity； and observed the reflections of his three s
