heroes of the telegraph-第33节

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g　against　one　the　voice　is　conveyed　through　the　string；　solely　by　mechanical　vibration；　to　the　other。　　Gray　employed　electricity；　and　varied　the　strength　of　the　current　in　conformity　with　the　voice　by　causing　the　diaphragm　in　vibrating　to　dip　a　metal　probe　attached　to　its　centre　more　or　less　deep　into　a　well　of　conducting　liquid　in　circuit　with　the　line。　　As　the　current　passed　from　the　probe　through　the　liquid　to　the　line　a　greater　or　less　thickness　of　liquid　intervened　as　the　probe　vibrated　up　and　down；　and　thus　the　strength　of　the　current　was　regulated　by　the　resistance　offered　to　the　passage　of　the　current。　　His　receiver　was　an　electro…magnet　having　an　iron　plate　as　an　armature　capable　of　vibrating　under　the　attractions　of　the　varying　current。　　But　Gray　allowed　his　idea　to　slumber；　whereas　Bell　continued　to　perfect　his　apparatus。　　However；　when　Bell　achieved　an　unmistakable　success；　Gray　brought　a　suit　against　him；　which　resulted　in　a　compromise；　one　public　company　acquiring　both　patents。

Bell's　invention　has　been　contested　over　and　over　again；　and　more　than　one　claimant　for　the　honour　and　reward　of　being　the　original　inventor　of　the　telephone　have　appeared。　　The　most　interesting　case　was　that　of　Signor　Antonio　Meucci；　an　Italian　emigrant；　who　produced　a　mass　of　evidence　to　show　that　in　1849；　while　in　Havanna；　Cuba；　he　experimented　with　the　view　of　transmitting　speech　by　the　electric　current。　　He　continued　his　researches　in　1852…3；　and　subsequently　at　Staten　Island；　U。S。；　and　in　1860　deputed　a　friend　visiting　Europe　to　interest　people　in　his　invention。　　In　1871　he　filed　a　caveat　in　the　United　States　Patent　Office；　and　tried　to　get　Mr。　Grant；　President　of　the　New　York　District　Telegraph　Company；　to　give　the　apparatus　a　trial。　　Ill…health　and　poverty；　consequent　on　an　injury　due　to　an　explosion　on　board　the　Staten　Island　ferry　boat　Westfield；　retarded　his　experiments；　and　prevented　him　from　completing　his　patent。　　Meucci's　experimental　apparatus　was　exhibited　at　the　Philadelphia　Exhibition　of　1884；　and　attracted　much　attention。　　But　the　evidence　he　adduces　in　support　of　His　early　claims　is　that　of　persons　ignorant　of　electrical　science；　and　the　model　shown　was　not　complete。　　The　caveat　of　1871　is　indeed　a　reliable　document；　but　unfortunately　for　him　it　is　not　quite　clear　from　it　whether　he　employed　a　'lovers'　telephone；'　with　a　wire　instead　of　a　string；　and　joined　a　battery　to　it　in　the　hope　of　enhancing　the　effect。　　'I　employ；'　he　says；　'the　well　known　conducting　effect　of　continuous　metallic　conductors　as　a　medium　for　sound；　and　increase　the　effect　by　electrically　insulating　both　the　conductor　and　the　parties　who　are　communicating。　　It　forms　a　speaking　telegraph　without　the　necessity　of　any　hollow　tube。'　In　connection　with　the　telephone　he　used　an　electric　alarm。　　It　is　by　no　means　evident　from　this　description　that　Meucci　had　devised　a　practicable　speaking　telephone；　but　he　may　have　been　the　first　to　employ　electricity　in　connection　with　the　transmission　of　speech。　　＇Meucci　is　dead。＇

'This　crowning　marvel　of　the　electric　telegraph；'　as　Sir　William　Thomson　happily　expressed　it；　was　followed　by　another　invention　in　some　respects　even　more　remarkable。　　During　the　winter　of　1878　Professor　Bell　was　in　England；　and　while　lecturing　at　the　Royal　Institution；　London；　he　conceived　the　idea　of　the　photophone。　　It　was　known　that　crystalline　selenium　is　a　substance　peculiarly　sensitive　to　light；　for　when　a　ray　strikes　it　an　electric　current　passes　far　more　easily　through　it　than　if　it　were　kept　in　the　dark。　　It　　therefore　occurred　to　Professor　Bell　that　if　a　telephone　were　connected　in　circuit　with　the　current；　and　the　ray　of　light　falling　on　the　selenium　was　eclipsed　by　means　of　the　vibrations　of　sound；　the　current　would　undulate　in　keeping　with　the　light；　and　the　telephone　would　emit　a　corresponding　note。　　In　this　way　it　might　be　literally　possible　'to　hear　a　shadow　fall　athwart　the　stillness。'

He　was　not　the　first　to　entertain　the　idea；　for　in　the　summer　of　1878；　one　'L。　F。　W。；'　writing　from　Kew　on　June　3　to　the　scientific　journal　NATURE　describes　an　arrangement　of　the　kind。　　To　Professor　Bell；　in　conjunction　with　Mr。　Summer　Tainter；　belongs　the　honour　of　having；　by　dint　of　patient　thought　and　labour；　brought　the　photophone　into　material　existence。　　By　constructing　sensitive　selenium　cells　through　which　the　current　passed；　then　directing　a　powerful　beam　of　light　upon　them；　and　occulting　it　by　a　rotary　screen；　he　was　able　to　vary　the　strength　of　the　current　in　such　a　manner　as　to　elicit　musical　tones　from　the　telephone　in　circuit　with　the　cells。　　Moreover；　by　reflecting　the　beam　from　a　mirror　upon　the　cells；　and　vibrating　the　mirror　by　the　action　of　the　voice；　he　was　able　to　reproduce　the　spoken　words　in　the　telephone。　　In　both　cases　the　only　connecting　line　between　the　transmitting　screen　or　mirror　and　the　receiving　cells　and　telephone　was　the　ray　of　light。　　With　this　apparatus；　which　reminds　us　of　the　invocation　to　Apollo　in　the　MARTYR　OF　ANTIOCH

　　　'Lord　of　the　speaking　lyre；　　　　That　with　a　touch　of　fire　　　　Strik'st　music　which　delays　the　charmed　spheres。'

Professor　Bell　has　accomplished　the　curious　feat　of　speaking　along　a　beam　of　sunshine　830　feet　long。　　The　apparatus　consisted　of　a　transmitter　with　a　mouthpiece；　conveying　the　sound　of　the　voice　to　a　silvered　diaphragm　or　mirror；　which　reflected　the　　vibratory　beam　through　a　lens　towards　the　selenium　receiver；　which　was　simply　a　parabolic　reflector；　in　the　focus　of　which　was　placed　the　selenium　cells　connected　in　circuit　with　a　battery　and　a　pair　of　telephones；　one　for　each　ear。　　The　transmitter　was　placed　in　the　top　of　the　Franklin　schoolhouse；　at　Washington；　and　the　receiver　in　the　window　of　Professor　Bell's　laboratory　in　L　Street。　　'It　was　impossible；'　says　the　inventor；　'to　converse　by　word　of　mouth　across　that　distance；　and　while　I　was　observing　Mr。　Tainter；　on　the　top　of　the　schoolhouse；　almost　blinded　by　the　light　which　was　coming　in　at　the　window　of　my　laboratory；　　and　vainly　trying　to　understand　the　gestures　he　was　making　to　me　at　that　great　distance；　the　thought　occurred　to　me　to　listen　to　the　telephones　connected　with　the　selenium　receiver。　　Mr。　Tainter　saw　me　　disappear　from　the　window；　and　at　once　spoke　to　the　transmitter。　　I　heard　him　distinctly　say；　〃Mr。　Bell；　if　you　hear　what　I　say；　come　to　the　window　and　wave　your　hat！　〃　It　is　needless　to　say　with　what　gusto　I　obeyed。'

The　spectroscope　has　demonstrated　the　truth　of　the　poet；　who　said　that　'light　is　the　voice　of　the　stars；'　and　we　have　it　on　the　authority　of　Professor　Bell　and　M。　Janssen；　the　celebrated　astronomer；　that　the　changing　brightness　of　the　photosphere；　as　produced　by　solar　hurricanes；　has　produced　a　feeble　echo　in　the　photophone。

Pursuing　these　researches；　Professor　Bell　discovered　that　not　only　the　selenium　cell；　but　simple　discs　of　wood；　glass；　metal；　ivory；　india…　rubber；　and　so　on；　yielded　a　distinct　note　when　the　intermittent　ray　of　light　fell　upon　them。　　Crystals　of　sulphate　of　copper；　chips　of　pine；　and　even　tobacco…smoke；　in　a　test…tube　held　before　the　beam；　emitted　a　musical　tone。　　With　a　thin　disc　of　vulcanite　as　receiver；　the　dark　　heat　rays　which　pass　through　an　opaque　screen　were　found　to　yield　a　note。　Even　the　outer　ear　is　itself　a　　receiver；　for　when　the　intermittent　beam　is　focussed　in　the　cavity　a　faint　musical　tone　is　heard。

Another　research　of　Professor　Bell　was　that　in　which　he　undertook　to　localise　the　assassin's　bullet　in　the　body　of　the　lamented　President　Garfield。　　In　1879　Professor　Hughes　brought　out　his　beautiful　induction　balance；　and　the　following　year　Professor　Bell；　who　had　already　worked　in　the　same　field；　consulted　him　by　telegraph　as　to　the　best　mode　of　applying　the　balance　to　determining　the　place　of　the　bullet；　which　had　hitherto　escaped　the　probes　of　the　President's　physicians。　　Professor　Hughes　advised　him　by　telegraph；　and　with　this　and　other　assistance　an　apparatus　was　devised　which　indicated　the　locality　of　the　ball。　　A　full　account　of　his　experiments　was　given　in　a　paper　read　before　the　American　Association　for　the　Advancement　of　Science　in　August；　1882。

Professor　Bell　continues　to　reside　in　the　United　States；　of　which　he　is　a　naturalised　citizen。　　He　is　married　to　a　daughter　of　Mr。　Gardiner　G。　Hubbard；　who　in　1860；　when　she　was　four　years　of　age；　lost　her　hearing　by　an　illness；　but　has　learned　to　converse　by　the　Horace…Mann　system　of　watching　the　lips。　　Both　he　and　his　father…in…law　（who　had　a　pecuniary　interest　in　his　patents）　have　made　princely　fortunes　by　the　introduction　of　the　telephone。



CHAPTER　IX。

THOMAS　ALVA　EDISON。

Thomas　Alva　Edison；　the　most　famous　inventor　of　his　time　and　country；　was　born　at　Milan；　Erie　County；　Ohio；　in　the　United　States；　on　February　11；　1847。　　His　pedigree　has　been　traced　for　two　centuries　to　a　family　of　prosperous　millers　in　Holland；　some　of　whom　emigrated　to　America　in　1730。　　　Thomas；　his　great…grandfather；　was　an　officer　of　a　bank　in　Manhattan　Island　during　the　Revolution；　and　his　signature　is　extant　on　the　old　notes　of　the　American　currency。　　Longevity　seems　a　characteristic　of　the　strain；　for　Thomas　lived　to　the　patriarchal　term　of　102；　his　son　to　103；　and　Samuel；　the　father　of　the　inventor；　is；　we