american hand book of the daguerreotype-第21部分

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lanishing　hammer　has　left　amazingly　visible　indications　of　its　busy　work。　One　would　suppose　the　manufacturer　intended　the　surface　of　the　plate　to　represent　the　undulations　of　the　sea；　instead　of　that　smooth　and　level　character　so　strongly　recommended　by　M。　Daguerre。

Such　a　plate　necessarily　requires　at　the　hand　of　the　operator　considerable　labor　before　the　surface　is　in　a　proper　condition　to　receive　a　suitable　polish　from　the　buffer。　The　least　reflection　in　the　world　should　teach　any　one　that　so　long　as　the　undulatory　character　continues　upon　the　surface　of　the　plate；　it　is　in　a　very　imperfect　condition　for　buffing；　because　the　buffer　cannot　touch　every　point　equally；　the　elevated　portions　alone　receiving　a　high　degree　of　polish　while　the　depressed　portion；　from　their　roughness　acting　as　nuclei；　gather　dust；　rouge；　and　other　foreign　bodies；　so　detrimental　to　sensitiveness。　The　secret　of　the　superior　judgment　and　skill　of　one　operator　over　another；　is　intimately　connected　with　this　point：　his　success　depends　very　much　upon　the　first　process　of　cleaning　the　plate。

Let　us　examine　the　manipulation　of　the　complaining　operator。　He　takes　one　of　these　plates　and　gives　it　a　careful　scouring　with　rotten…stone　and　alcohol　or　any　other　liquid　preferred　for　this　part　of　the　operationthat　is；　he　gives　it　what　he　terms　a　careful　scouring　very　gently　indeed　because；　from　the　frequent　trials　he　is　in　the　habit　of　making　in　the　camera；　he　fears　he　will　rub　the　silver　entirely　away　before　he　succeeds　in　obtaining　a　good　impression。　The　dark　patches；　specks；　and　granular　appearance　resulting　entirely　from　the　unevenness　of　the　surface　of　the　plate；　look　like　copper　to　him；　and　he　is　surprised　that　he　should　have　rubbed　away　the　silver　so　soon；　particularly　by　such　delicate　handling。

The　judgment　and　experience　of　the　successful　operator；　however；　teach　him　that　scouring　injures　a　plate　less　than　buffing。　He　knows　that　unless　the　hammer　marks　be　obliterated；　he　cannot　by　the　buffer　produce　a　surface　of　uniform　polish　and　sensitiveness；　without　which　a　fair　proof　is　extremely　doubtful；　he　knows　that　the　time　employed　in　the　preliminary　operation　of　cleaning　the　plate　properly　is　economy。

There　is　a　style　of　French　plates　in　the　market；　denominated　heavy；　which　are　truly　excellent；　if　properly　managed。　　Much　patience；　however；　is　required　to　remove　the　marks　of　the　hammer；　but　with　tripoli　and　alcohol　the　surface　is　readily　cut　down；　and　the　plate　is　then　susceptible　of　a　beautiful　black　lustre　by　polishing　with　the　buffer。　　The　complaining　operator　could　not　succeed　by　his　own　method　with　one　of　the　plates；　he　would　encounter　all　manner　of　clouds　and　other　unaccountable　phenomena；　he　would　imagine　this　plate　entirely　worn　out　before　it　was　half　cleaned；　and　soon　fix　in　his　own　estimation　the　reputation　of　the　heavy　plate。

In　making　a　choice　of　plates；　therefore；　it　would　appear　to　be　a　matter　of　perfect　indifference　with　an　experienced　operator　what　kind　he　would　use；　except　so　far　only　as　the　labor　required　in　cleaning　them　was　to　be　taken　into　consideration。

The　distinction　between　a　scale　plate；　a　Scovill　No。　1；　S。　F。；　heavy　A；　star；　crescent；　eagle；　or　any　other　brand；　consists　in　the　superior　finish　of　some；　and　the　thinness　of　the　silver　in　the　cheaper　qualities。

Consequently；　let　the　complaining　operator　but　employ　the　diligence　inculcated　in　this　article；　to　clean　his　plate　thoroughly；　so　as　to　bring　it　to　a　perfectly　even　and　level　surface；　and　he　will　seldom　be　troubled　with　specks；　clouds；　dark　patches；　and　the　host　of　other　obstacles　which　heretofore　have　tormented　him。



CHAPTER　VI。

AN　ACCOUNT　OF　WOLCOTT　AND　JOHNSON'S　EARLY　EXPERIMENTS；　IN　THE　DAGUERREOTYPE。　BY　JOHN　JOHNSON。

＇From　Humphrey's　Journal；　vol。　　ii　185l＇

As　a　general　thing；　however　perfect　any　invention　may　be　deemed　by　the　inventor　or　discoverer；　it　falls　to　the　lot　of　most；　to　be　the　subject　of　improvement　and　advancement；　and　especially　is　this　the　case　with　those　new　projects　in　science　which　open　an　untrodden　field　to　the　view　of　the　artisan。　　Such　has　been；　in　an　eminent　degree；　the　case　with　the　discovery　first　announced　to　the　world　by　Mons。　　Jean　Jaques　Claude　Daguerre；　of　Paris；　in　the　year　1839；　and　which　excited　unbounded　astonishment；　curiosity　and　surprise。　　It　may　be　questioned　had　any　other　than　Daguerre　himself　discovered　a　like　beautiful　combination；　whether　the　world　would　have　been　favored　with　details　exhibiting　so　much　care；　patience　and　perseverance　as　the　Daguerreotype　on　its　introduction。　　Shortly　after；　these　details　reached　the　United　States；　by　Professor　S。　F。　B。　Morse；　of　New　York；　who　was；　at　the　time　of　the　discovery；　residing　in　Paris。　By　this　announcement；　the　whole　scientific　corps　was　set　in　operation；　many　repeating　the　experiments；　following　carefully　the　directions　pointed　out　by　Daguerre；　as　being　necessary　to　success。　Among　the　number　in　the　United　States；　was　Alexander　S。　Wolcott　（since　deceased）　and　myself；　both　of　this　city。　　On　the　morning　of　the　6th　day　of　October；　1839；　I　took　to　A。　Wolcott's　residence；　a　full　description　of　Daguerre's　discovery；　he　being　at　the　time　engaged　in　the　department　of　Mechanical　Dentistry；　on　some　work　requiring　his　immediate　attention；　the　work　being　promised　at　2　P。M。　that　day；　having；　therefore；　no　opportunity　to　read　the　description　for　himself　（a　thing　he　was　accustomed　to　do　at　all　times；　when　investigating　any　subject）。　I　read　to　him　the　paper；　and　proposed　to　him　that　if　he　would　plan　a　camera　（a　matter　he　was　fully　acquainted　with；　both　theoretically　and　practically）；　I　would　obtain　the　materials　as　specified　by　Daguerre。　This　being　agreed　to；　I　departed　for　the　purpose；　and　on　my　return　to　his　shop；　he　handed　me　the　sketch　of　a　camera　box；　without　at　all　explaining　in　what　manner　the　lens　was　to　be　mounted。　This　I　also　undertook　to　procure。　　After　2；　P。M。；　he　had　more　leisure；　when　he　proceeded　to　complete　the　camera；　introducing　for　that　purpose　a　reflector　in　the　back　of　the　box；　and　also　to　affix　a　plate　holder　on　the　inside；　with　a　slide　to　obtain　the　focus　on　the　plate；　prepared　after　the　manner　of　Daguerre。　While　Mr。　Wolcott　was　engaged　with　the　camera；　I　busied　myself　in　polishing　the　silver　plate；　or　rather　silver　plated　copper；　but　ere　reaching　the　end　preparatory　to　iodizing；　I　found　I　had　nearly　or　quite　removed　the　silver　surface　from　off　the　plate；　and　that　being　the　best　piece　of　sliver…plated　copper　to　be　found；　the　first　remedy　at　hand　that　suggested　itself；　was　a　burnisher；　and　a　few　strips　were　quickly　burnished　and　polished。　　Meantime。　　the　camera　being　finished；　Mr。　Wolcott；　after　reading　for　himself　Daguerre's　method　of　iodizing；　prepared　two　plates；　and　placing　them　in　the　camera；　guessed　at　the　required　time　they　should　remain　exposed　to　the　action　of　the　light；　after　mercurializing　each　in　turn；　and　removing　the　iodized　surface　with　a　solution　of　common　salt　two　successful　impressions　were　obtained；　each　unlike　the　other！　Considerable　surprise　was　excited　by　this　result；　for　each　plate　was　managed　precisely　like　the　other。　　On　referring　to　Daguerre；　no　explanation　was　found　for　this　strange　result；　time；　however；　revealed　to　us　that　one　picture　was　positive；　and　the　other　negative。　On　this　subject　I　shall　have　much　to　say　during　the　progress　of　the　work。　　Investigating；　the　cause　of　this　difference　occupied　the　remainder　of　that　day。　　However；　another　attempt　was　agreed　upon；　and　the　instruments；　plates；　etc。；　prepared　and　taken　up　into　an　attic　room；　in　a　position　most　favorable　for　light。　Having　duly　arranged　the　camera；　I　sat　for　five　minutes；　and　the　result　was　a　profile　miniature　（a　miniature　in　reality；）　or　a　plate　not　quite　three…eighths　of　an　inch　square。　　Thus；　with　much　deliberation　and　study；　passed　the　first　day　in　Daguerreotype　little　dreaming　or　knowing　into　what　a　labyrinth　such　a　beginning　was　hastening　us。

＇Description　of　apparatus　represented　on　pages　192　and　199：＇

　A。The　Boxabout　4　inches　long　by　about　2　outside　diameter。　　B。The　Reflector　soldered　to　a　brass　screw；　and　mounted　in　the　　　　　　rear　of　the　box。　　c。The　slide　to　regulate　the　focus　to　the　plate　holder。　　d。The　standard　to　the　plate　holder　screwed　to　the　slide。　　f。The　plate…holder　frame　having　two　small　ledges；　*　*；　for　the　　　　　　plate　to　rest　upon。

＇page　192＇

　g。The　plate　resting　upon　the　ledge。；　*　*；　and　kept　against　the　　　　　　frame　by　the　spring　h。　　The　plates　used　were　about　3/8　of　an　inch　　　　　　square。　　A。The　window　with　the　sashes　removed。

B　and　C　（p。　199）　are　large　looking…glasses　mounted　as　plain　reflectors；　the　lower　one　C　having　rotary　motion　upon　the　saddle；　resting　upon　the　sill　of　the　window　in　order　to　direct　the　rays　of　the　sun　upon　the　reflector　B；　at　any　hour　of　the　daythe　vertical　motion　of　the　reflector　C

＇amdg_12。gif＇

being　necessary；　the　sun　varying　in　altitude　so　much　during　the　hours　most　favorable　to　the　production　of　portraits。　The　reflector　C　was

＇page　193＇

kept　up　to　the　required　position　by　the　handle　lever；　upright　post　and　bolts。　Reflector　B　was　hinged　at　its　upper　end　at　the　top　of　the　window　frame；　the　only　motion　being　necessary　was　that　which　would　reflect　upon　the　sitter　the　incident　rays　from　reflector　Cthe　reflector　B　being　kept　at　the　required　angle　by　the　connecting　lever　m；　etc。　　Suitable　back…grounds　were　placed　behind　the　sitter。

The　reflector　B　and　C；　had　frequently　to　be　renewed；　the　heat　of　the　sun　soon　destroying　their　brilliance　or　power　of　reflecting；　light；　before　renewing　them；　however；　we　resorted　to　the　springing　of　them；　by　which　means　their　power　was　increased　for　a　period。

The　camera　or　reflecting　apparatus；　invented　by　Mr。　Wolcott；　was；　from　the　nature　of　the　case；　better　adapted　at　that　day　to　the　taking　of　portraits　from　life；　than　any　other　instruments。　After　carefully　examining　the　camera　described　by　Daguerre；　and　the　time　stated　as　necessary　to　produce　action　for　an　image；　it　became　evident　to　the　mind　of　Mr。　Wolcott　at　once；　that　more　light　could　be　obtained　（as　the　field　of　view　required　was　not　large）　by　employing　a　reflector　of　short　focus　and　wide　aperture；　than　from　a　lens　arrangement；　owing　to　spherical　aberration　and　other　causes。　Many　experiments　having　been　tried　with　the　sma