heroes of the telegraph-第3部分

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hem　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　sparks　in　it。　　The　points　of　the　wire　were　so　arranged　that　if　the　sparks　were　instantaneous；　their　reflections　would　appear　in　one　straight　line；　but　the　middle　one　was　seen　to　lag　behind　the　others；　because　it　was　an　instant　later。　　The　electricity　had　taken　a　certain　time　to　travel　from　the　ends　of　the　wire　to　the　middle。　　This　time　was　found　by　measuring　the　amount　of　lag；　and　comparing　it　with　the　known　velocity　of　the　mirror。　　Having　got　the　time；　he　had　only　to　compare　that　with　the　length　of　half　the　wire；　and　he　found　that　the　velocity　of　electricity　was　288；000　miles　a　second。

Till　then；　many　people　had　considered　the　electric　discharge　to　be　instantaneous；　but　it　was　afterwards　found　that　its　velocity　depended　on　the　nature　of　the　conductor；　its　resistance；　and　its　electro…static　capacity。　　Faraday　showed；　for　example；　that　its　velocity　in　a　submarine　wire；　coated　with　insulator　and　surrounded　with　water；　is　only　144；000　miles　a　second；　or　still　less。　　Wheatstone's　device　of　the　revolving　mirror　was　afterwards　employed　by　Foucault　and　Fizeau　to　measure　the　velocity　of　light。

In　1835；　at　the　Dublin　meeting　of　the　British　Association；　Wheatstone　showed　that　when　metals　were　volatilised　in　the　electric　spark；　their　light；　examined　through　a　prism；　revealed　certain　rays　which　were　characteristic　of　them。　　Thus　the　kind　of　metals　which　formed　the　sparking　points　could　be　determined　by　analysing　the　light　of　the　spark。　This　suggestion　has　been　of　great　service　in　spectrum　analysis；　and　as　applied　by　Bunsen；　Kirchoff；　and　others；　has　led　to　the　discovery　of　several　new　elements；　such　as　rubidium　and　thallium；　as　well　as　increasing　our　knowledge　of　the　heavenly　bodies。　　Two　years　later；　he　called　attention　to　the　value　of　thermo…electricity　as　a　mode　of　generating　a　current　by　means　of　heat；　and　since　then　a　variety　of　thermo…piles　have　been　invented；　some　of　which　have　proved　of　considerable　advantage。

Wheatstone　abandoned　his　idea　of　transmitting　intelligence　by　the　mechanical　vibration　of　rods；　and　took　up　the　electric　telegraph。　　In　1835　he　lectured　on　the　system　of　Baron　Schilling；　and　declared　that　the　means　were　already　known　by　which　an　electric　telegraph　could　be　made　of　great　service　to　the　world。　　He　made　experiments　with　a　plan　of　his　own；　and　not　only　proposed　to　lay　an　experimental　line　across　the　Thames；　but　to　establish　it　on　the　London　and　Birmingham　Railway。　　Before　these　plans　were　carried　out；　however；　he　received　a　visit　from　Mr。　Fothergill　Cooke　at　his　house　in　Conduit　Street　on　February　27；　1837；　which　had　an　important　influence　on　his　future。

Mr。　Cooke　was　an　officer　in　the　Madras　army；　who；　being　home　on　furlough；　was　attending　some　lectures　on　anatomy　at　the　University　of　Heidelberg；　where；　on　March　6；　1836；　he　witnessed　a　demonstration　with　the　telegraph　of　Professor　Moncke；　and　was　so　impressed　with　its　importance；　that　he　forsook　his　medical　studies　and　devoted　all　his　efforts　to　the　work　of　introducing　the　telegraph。　　He　returned　to　London　soon　after；　and　was　able　to　exhibi