The　History　and　Practice　of　the　Art　of　Photography
  by　Henry　H。　Snelling
  PREFACE。
  The　object　of　this　little　work　is　to　fill　a　void　much　complained　of　by　Daguerreotypistsparticularly　young　beginers。
  The　author　has　waited　a　long　time　in　hopes　that　some　more　able　pen　would　be　devoted　to　the　subject；　but　the　wants　of　the　numerous；　and　constantly　increasing；　class；　just　mentioned；　induces　him　to　wait　no　longer。
  All　the　English　works　on　the　subjectparticularly　on　the　practical　application；　of　Photogenic　drawingare　deficient　in　many　minute　details；　which　are　essential　to　a　complete　understanding　of　the　art。　Many　of　their　methods　of　operating　are　entirely　different　from；　and　much　inferior　to；　those　practised　in　the　United　States：　their　apparatus；　also；　cannot　compare　with　ours　for　completeness；　utility　or　simplicity。
  I　shall；　therefore；　confine　myself　principallyso　far　as　Photogenic　drawing　upon　metalic　plates　is　concernedto　the　methods　practised　by　the　most　celebrated　and　experienced　operators；　drawing　upon　French　and　English　authority　only　in　cases　where　I　find　it　essential　to　the　purpose　for　which　I　design　my　work；　namely：　　furnishing　a　complete　system　of　Photography；　such　an　one　as　will　enable　any　gentleman；　or　lady；　who　may　wish　to　practise　the　art；　for　profit　or　amusement；　to　do　so　without　the　trouble　and　expense　of　seeking　instruction　from　professors；　which　in　many　cases　within　my　own　knowledge　has　prevented　persons　from　embracing　the　profession。
  To　English　authors　I　am　principally　indebted　for　that　portion　of　my　work　relating　to　Photogenic　drawing　on　paper。　To　them　we　owe　nearly　all　the　most　important　improvements　in　that　branch　of　the　art。　　Besides；　it　has　been　but　seldom　attempted　in　the　United　States；　and　then　without　any　decided　success。　Of　these　attempts　I　shall　speak　further　in　the　Historical　portion　of　this　volume。
  Every　thing　essential；　therefore；　to　a　complete　knowledge　of　the　whole　art；　comprising　all　the　most　recent　discoveries　and　improvements　down　to　the　day　of　publication　will　be　found　herein　laid　down。
  INTRODUCTION
  New　York；　January　27；　1849。　　E。　ANTHONY；　ESQ。
  Dear　Sir；In　submiting　the　accompanying　〃History　and　Practice　of　Photography　to　your　perusal；　and　for　your　approbation；　I　do　so　with　the　utmost　confidence　in　your　ability　as　a　practical　man；　long　engaged　in　the　science　of　which　it　treats；　as　well　as　your　knowledge　of　the　sciences　generally；　as　well　as　your　regard　for　candor。　To　you；　therefore；　I　leave　the　decision　whether　or　no　I　have　accomplished　my　purpose；　and　produced　a　work　which　may　not　only　be　of　practical　benefit　to　the　Daguerrean　artist；　but　of　general　interest　to　the　reading　public；　and　your　decision　will　influence　me　in　offering　it　for；　or　withholding　it　from；　publication。
  If　it　meets　your　approbation；　I　would　most　respectfully　ask　permission　to　dedicate　it　to　you；　subscribing　myself；　　With　esteem；　　Ever　truly　yours；　　HENRY　H。　SNELLING
  New　York；　February　1st；　1849。　　Mr。　H。　H。　SNELLING。
  Dear　SirYour　note　of　January　27th；　requesting　permission　to　dedicate　to　me　your　〃History　and　Practice　of　Photography；〃　I　esteem　a　high　compliment；　particularly　since　I　have　read　the　manuscript　of　your　work。
  Such　a　treatise　has　long　been　needed；　and　the　manner　in　which　you　have　handled　the　subject　will　make　the　book　as　interesting　to　the　reading　public　as　it　is　valuable　to　the　Daguerrean　artist；　or　the　amateur　dabbler　in　Photography。　I　have　read　nearly　all　of　the　many　works　upon　this　art　that　have　emanated　from　the　London　and　Paris　presses；　and　I　think　the　reader　will　find　in　yours　the　pith　of　them　all；　with　much　practical　and　useful　information　that　I　do　not　remember　to　have　seen　communicated　elsewhere。
  There　is　much　in　it　to　arouse　the　reflective　and　inventive　faculties　of　our　Daguerreotypists。　　They　have　heretofore　stumbled　along　with　very　little　knowledge　of　the　true　theory　of　their　art；　and　yet　the　quality　of　their　productions　is　far　in　advance　of　those　of　the　French　and　English　artists；　most　of　whose　establishments　I　have　had　the　pleasure　of　visiting　I　feel　therefore；　that　when　a　sufficient　amount　of　theoretic　knowledge　shall　have　been　added　to　this　practical　skill　on　the　part　of　our　operators；　and　when　they　shall　have　been　made　fully　acquainted　with　what　has　been　attained　or　attempted　by　others；　a　still　greater　advance　in　the　art　will　be　manifested。
  A　GOOD　Daguerreotypist　is　by　no　means　a　mere　machine　following　a　certain　set　of　fixed　rules。　　Success　in　this　art　requires　personal　skill　and　artistic　taste　to　a　much　greater　degree　than　the　unthinking　public　generally　imagine；　in　fact　more　than　is　imagined　by　nine…tenths　of　the　Daguerreotypists　themselves。　And　we　see　as　a　natural　result；　that　while　the　business　numbers　its　thousands　of　votaries；　but　few　rise　to　any　degree　of　eminence。　It　is　because　they　look　upon　their　business　as　a　mere　mechanical　operation；　and　having　no　aim　or　pride　beyond　the　earning　of　their　daily　bread；　they　calculate　what　will　be　a　fair　per　centage　on　the　cost　of　their　plate；　case；　and　chemicals；　leaving　MIND；　which　is　as　much　CAPITAL　as　anything　else　（where　it　is　exercised；）　entirely　out　of　the　question。
  The　art　of　taking　photographs　on　PAPER；　of　which　your　work　treats　at　considerable　length；　has　as　yet　attracted　but　little　attention　in　this　country；　though　destined；　as　I　fully　believe；　to　attain　an　importance　far　superior　to　that　to　which　the　Daguerreotype　has　risen。
  The　American　mind　needs　a　waking　up　upon　the　subject；　and　I　think　your　book　will　give　a　powerful　impulse　in　this　direction。　In　Germany　a　high　degree　of　perfection　has　been　reached；　and　I　hope　your　countrymen　will　not　be　slow　to　follow。
  Your　interesting　account　of　the　experiments　of　Mr。　Wattles　was　entirely　new　to　me；　and　is　another　among　the　many　evidences　that　when　the　age　is　fully　ripe　for　any　great　discovery；　it　is　rare　that　it　does　not　occur　to　more　than　a　single　mind。
  Trusting　that　your　work　will　meet　with　the　encouragement　which　your　trouble　in　preparing　it　deserves；　and　with　gratitude　for　the　undeserved　compliment　paid　to　me　in　its　dedication；
  I　remain；　very　sincerely；　　Your　friend　and　well　wisher；　　E。　ANTHONY。
  PHOTOGRAPHY。
  CHAP。　I。
  A　BRIEF　HISTORY　OF　THE　ART。
  As　in　all　cases　of　great　and　valuable　inventions　in　science　and　art　the　English　lay　claim　to　the　honor　of　having　first　discovered　that　of　Photogenic　drawing。　　But　we　shall　see　in　the　progress　of　this　history；　that　like　many　other　assumptions　of　their　authors；　priority　in　this　is　no　more　due　them；　then　the　invention　of　steamboats；　or　the　cotton　gin。
  This　claim　is　founded　upon　the　fact　that　in　1802　Mr。　Wedgwood　recorded　an　experiment　in　the　Journal　of　the　Royal　Institution　of　the　following　nature。
  〃A　piece　of　paper；　or　other　convenient　material；　was　placed　upon　a　frame　and　sponged　over　with　a　solution　of　nitrate　of　silver；　it　was　then　placed　behind　a　painting　on　glass　and　the　light　traversing　the　painting　produced　a　kind　of　copy　upon　the　prepared　paper；　those　parts　in　which　the　rays　were　least　intercepted　being　of　the　darkest　hues。　　Here；　however；　terminated　the　experiment；　for　although　both　Mr。　Wedgwood　and　Sir　Humphry　Davey　experimented　carefully；　for　the　purpose　of　endeavoring　to　fix　the　drawings　thus　obtained；　yet　the　object　could　not　be　accomplished；　and　the　whole　ended　in　failure。〃
  This；　by　their　own　showing；　was　the　earliest　attempt　of　the　English　savans。　But　this　much　of　the　principle　was　known　to　the　Alchemists　at　an　early　date　although　practically　produced　in　another　wayas　the　following　experiment；　to　be　found　in　old　books；　amply　proves。
  〃Dissolve　chalk　in　aquafortis　to　the　consistence　of　milk；　and　add　to　it　a　strong　solution　of　silver；　keep　this　liquor　in　a　glass　bottle　well　stopped；　then　cutting　out　from　a　piece　of　paper　the　letters　you　would　have　appear；　paste　it　on　the　decanter；　and　lay　it　in　the　sun's　rays　in　such　a　manner　that　the　rays　may　pass　through　the　spaces　cut　out　of　the　paper　and　fall　on　the　surface　of　the　liquor　the　part　of　the　glass　through　which　the　rays　pass　will　be　turned　black；　while　that　under　the　paper　remains　white；　but　particular　care　must　be　observed　that　the　bottle　be　not　moved　during　the　operation。〃
  Had　not　the　alchemists　been　so　intent　upon　the　desire　to　discover　the　far　famed　philosopher's　stone；　as　to　make　them　unmindful　of　the　accidental　dawnings　of　more　valuable　discoveries；　this　little　experiment　in　chemistry　might　have　induced　them　to　prosecute　a　more　thorough　search　into　the　principle；　and　Photogenic　art　would　not　now；　as　it　is；　be　a　new　one。
  It　is　even　asserted　that　the　Jugglers　of　India　were　for　many　ages　in　possession　of　a　secret　by　which　they　were　enabled；　in　a　brief　space；　to　copy　the　likeness　of　any　individual　by　the　action　of　light。　This　fact；　if　fact　it　be；　may　account　for　the　celebrated　magic　mirrors　said　to　be　possessed　by　these　jugglers；　and　probable　cause　of　their　power　over　the　people。
  However；　as　early　as　1556　the　fact　was　established　that　a　combination　of　chloride　and　silver。　called；　from　its　appearance；　horn　silver；　was　blackened　by　the　sun's　rays；　and　in　the　latter　part　of　the　last　century　Mrs。　Fulhame　published　an　experiment　by　which　a　ch