heroes of the telegraph-第45章

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　or　premeditation　he　is　able　by　uniting　scattered　thoughts　to　add　a　novel　instrument　to　a　domain　of　science　with　which　he　has　little　acquaintance。　　Nay；　the　lessons　of　experience　and　the　scruples　of　intimate　knowledge　sometimes　deter　a　master　from　attempting　　what　the　tyro；　with　the　audacity　of　genius　and　the　hardihood　of　ignorance；　achieves。　　Theorists　have　been　known　to　pronounce　against　a　promising　invention　which　has　afterwards　been　carried　to　success；　and　it　is　not　improbable　that　if　Edison　had　been　an　authority　in　acoustics　he　would　never　have　invented　the　phonograph。　　It　happened　in　this　wise。　During　the　spring　of　1877；　he　was　trying　a　device　for　making　a　telegraph　message；　received　on　one　line；　automatically　repeat　itself　along　another　line。　　This　he　did　by　embossing　the　Morse　signals　on　the　travelling　paper　instead　of　merely　inking　them；　and　then　causing　the　paper　to　pass　under　the　point　of　a　stylus；　which；　by　rising　and　falling　in　the　indentations；　opened　and　closed　a　sending　key　included　in　the　circuit　of　the　second　line。　　In　this　way　the　received　message　transmitted　itself　further；　without　the　aid　of　a　telegraphist。　　Edison　was　running　the　cylinder　which　carried　the　embossed　paper　at　a　high　speed　one　day；　partly；　as　we　are　told；　for　amusement；　and　partly　to　test　the　rate　at　which　a　clerk　could　read　a　message。　　As　the　speed　was　raised；　the　paper　gave　out　a　humming　rhythmic　sound　in　passing　under　the　stylus。　　The　separate　signals　of　the　message　could　no　longer　be　distinguished　by　the　ear；　and　the　instrument　seemed　to　be　speaking　in　a　language　of　its　own；　resembling　'human　talk　heard　indistinctly。'　Immediately　it　flashed　on　the　inventor　that　if　he　could　emboss　the　waves　of　speech　upon　the　paper　the　words　would　be　returned　to　him。　　To　conceive　was　to　execute；　and　it　was　but　the　work　of　an　hour　to　provide　a　vibrating　diaphragm　or　tympanum　fitted　with　an　indenting　stylus；　and　adapt　it　to　the　apparatus。　　Paraffined　paper　was　selected　to　receive　the　indentations；　and　substituted　for　the　Morse　paper　on　the　cylinder　of　the　machine。　　On　speaking　to　the　tympanum；　as　the　cylinder　was　revolved；　a　record　of　the　vibrations　was　indented　on　the　paper；　and　by　re…passing　this　under　the　indenting　point　an　imperfect　reproduction　of　the　sounds　was　heard。　　Edison　'saw　at　once　that　the　problem　of　registering　human　speech；　so　that　it　could　be　repeated　by　mechanical　means　as　often　as　might　he　desired；　was　solved。'　＇T。　A。　Edison；　NORTH　AMERICAN　REVIEW；　June；　1888；　New　York　ELECTRICAL　REVIEW；　1888；＇

The　experiment　shows　that　it　was　partly　by　accident；　and　not　by　reasoning　on　theoretical　knowledge；　that　the　phonograph　was　discovered。　The　sound　resembling　'human　talk　heard　indistinctly'　seems　to　have　suggested　it　to　his　mind。　　This　was　the　germ　which　fell　upon　the　soil　prepared　for　it。　　Edison's　thoughts　had　been　dwelling　on　the　telephone；　he　knew　that　a　metal　tympanum　was　capable　of　vibrating　with　all　the　delicacies　of　speech；　and　it　occurred　to　him　that　if　these　vibrations　could　be　impressed　on　a　yielding　material；　as　the　Morse　signals　were　embossed　upon　the　paper；　the　indentations　would　reproduce　the　speech；　just　as　the　furrows　of　the　paper　reproduced　the　Morse　signals。　　The　tympanum　vibrating　in　the　curves　of　speech　was　instantly　united　in　his　imagination　with　the　embossing　stylus　and　the　long　and　short　indentations　on　the　Morse　paper；　the　idea　of　the　phonograph　flashed　upon　him。　　Many　a　one　versed　in　acoustics　would　probably　have　been　restrained　by　the　practical　difficulty　of　impressing　the　vibrations　on　a　yielding　material；　and　making　them　react　upon　the　reproducing　tympanum。　　But　Edison；　with　that　daring　mastery　over　matter　which　is　a　characteristic　of　his　mechanical　genius；　put　it　confidently　to　the　test。

Soon　after　this　experiment；　a　phonograph　was　constructed；　in　which　a　sheet　of　tinfoil　was　wrapped　round　a　revolving　barrel　having　a　spiral　groove　cut　in　its　surface　to　allow　the　point　of　the　indenting　stylus　to　sink　into　the　yielding　foil　as　it　was　thrust　up　and　down　by　the　vibrating　tympanum。　　This　apparatus　the　first　phonographwas　published　to　the　world　in　1878；　and　created　a　universal　sensation。　＇SCIENTIFIC　AMERICAN；　March　30；　1878＇　　It　is　now　in　the　South　Kensington　Museum；　to　which　it　was　presented　by　the　inventor。

The　phonograph　was　first　publicly　exhibited　in　England　at　a　meeting　of　the　Society　of　Telegraph　Engineers；　where　its　performances　filled　the　audience　with　astonishment　and　delight。　　A　greeting　from　Edison　to　his　electrical　brethren　across　the　Atlantic　had　been　impressed　on　the　tinfoil；　and　was　spoken　by　the　machine。　　Needless　to　say；　the　voice　of　the　inventor；　however　imperfectly　reproduced；　was　hailed　with　great　enthusiasm；　which　those　who　witnessed　will　long　remember。　　In　this　machine；　the　barrel　was　fitted　with　a　crank；　and　rotated　by　handle。　　A　heavy　flywheel　was　attached　to　give　it　uniformity　of　motion。　　A　sheet　of　tinfoil　formed　the　record；　and　the　delivery　could　he　heard　by　a　roomful　of　people。　　But　articulation　　was　sacrificed　at　the　expense　of　loudness。　　It　was　as　though　a　parrot　or　a　punchinello　spoke；　and　sentences　which　were　unexpected　could　not　be　understood。　　Clearly；　if　the　phonograph　were　to　become　a　practical　instrument；　it　required　to　be　much　improved。　Nevertheless　this　apparatus　sufficiently　demonstrated　the　feasibility　of　storing　up　and　reproducing　speech；　music；　and　other　sounds。　　Numbers　of　them　were　made；　and　exhibited　to　admiring　audiences；　by　license；　and　never　failed　to　elicit　both　amusement　and　applause。　　To　show　how　striking　were　its　effects；　and　how　surprising；　even　to　scientific　men；　it　may　be　mentioned　that　a　certain　learned　SAVANT；　on　hearing　it　at　a　SEANCE　of　the　Academie　des　Sciences；　Paris；　protested　that　it　was　a　fraud；　a　piece　of　trickery　or　ventriloquism；　and　would　not　be　convinced。

After　1878　Edison　became　too　much　engaged　with　the　development　of　the　electric　light　to　give　much　attention　to　the　phonograph；　which；　however；　was　not　entirely　overlooked。　　His　laboratory　at　Menlo　Park；　New　Jersey；　where　the　original　experiments　were　made；　was　turned　into　a　factory　for　making　electric　light　machinery；　and　Edison　removed　to　New　York　until　his　new　laboratory　at　Orange；　New　Jersey；　was　completed。　　Of　late　he　has　occupied　the　latter　premises；　and　improved　the　phonograph　so　far　that　it　is　now　a　serviceable　instrument。　　In　one　of　his　1878　patents；　the　use　of　wax　to　take　the　records　in　place　of　tinfoil　is　indicated；　and　it　is　chiefly　to　the　adoption　of　this　material　that　the　success　of　the　'perfected　phonograph'　is　due。　　Wax　is　also　employed　in　the　'graphophone'　of　Mr。　Tainter　and　Professor　Bell；　which　is　merely　a　phonograph　under　another　name。　　Numerous　experiments　have　been　made　by　Edison　to　find　the　bees…wax　which　is　best　adapted　to　receive　the　record；　and　he　has　recently　discovered　a　new　material　or　mixture　which　is　stated　to　yield　better　results　than　white　wax。

The　wax　is　moulded　into　the　form　of　a　tube　or　hollow　cylinder；　usually　4　1/4　inches　long　by　2　inches　in　diameter；　and　1/8　inch　thick。　　Such　a　size　is　capable　of　taking　a　thousand　words　on　its　surface　along　a　delicate　spiral　trace；　and　by　paring　off　one　record　after　another　can　be　used　fifteen　times。　　There　are　a　hundred　or　more　lines　of　the　trace　in　the　width　of　an　inch；　and　they　are　hardly　visible　to　the　naked　eye。　Only　with　a　magnifying　glass　can　the　undulations　caused　by　the　vibrating　stylus　be　distinguished。　　This　tube　of　wax　is　filed　upon　a　metal　barrel　like　a　sleeve；　and　the　barrel；　which　forms　part　of　a　horizontal　spindle；　is　rotated　by　means　of　a　silent　electro…motor；　controlled　by　a　very　sensitive　governor。　　A　motion　of　translation　is　also　given　to　the　barrel　as　it　revolves；　so　that　the　marking　stylus　held　over　it　describes　a　spiral　path　upon　its　surface。　　In　front　of　the　wax　two　small　metal　tympanums　are　supported；　each　carrying　a　fine　needle　point　or　stylus　on　its　under　centre。　　One　of　these　is　the　recording　diaphragm；　which　prints　the　sounds　in　the　first　place；　the　other　is　the　reproducing　diaphragm；　which　emits　the　sounds　recorded　on　the　wax。　They　are　used；　one　at　a　time；　as　the　machine　is　required；　to　take　down　or　to　render　back　a　phonographic　message。

The　recording　tympanum；　which　is　about　the　size　of　a　crown