the history and practice of the art of photography-第7部分

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　flat　brush；　and　dried　in　the　air。　If　alcohol　be　not　added；　it　must　be　applied　immediately；　as　the　air　changes　or　destroys　the　color　instantly。

Most　flowers　give　out　their　coloring　matter　to　alcohol　or　water　but　the　former　is　found　to　weaken；　and　in　some　cases　to　discharge　altogether　these　colors；　but　they　are　in　most　cases　restored　in　drying。　Paper　tinged　with　vegetable　colors　must　be　kept　perfectly　dry　and　in　darkness。

To　secure　an　eveness　of　tint　on　paper　it　should　be　first　moistened　on　the　back　by　sponging；　and　blotting　off　with　bibulous　paper。　　It　should　then　be　pinned　on　a　board；　the　moist　side　downwards；　so　that　two　of　its　edges　the　right　and　lower　onesproject　a　little　over　those　of　the　board。　Incline　the　board　twenty　or　thirty　degrees　to　the　horizon；　and　apply　the　tincture　with　a　brush　in　strokes　from　right　to　left；　taking　care　not　to　go　over　the　edges　which　rests　on　the　board；　but　to　pass　clearly　over　those　that　project；　and　also　observing　to　carry　the　tint　from　below　upwards　by　quick　sweeping　strokes；　leaving　no　dry　spaces　between　them。　　Cross　these　with　other　strokes　from　above　downwards；　leaving　no　floating　liquid　on　the　paper。　Dry　as　quickly　as　possible；　avoiding；　however；　such　heat　as　may　injure　the　tint



CHAP。　IV。

A　FEW　HINTS　AND　SUGGESTIONS　TO　DAGUERREOTYPISTS。


There　are　very　few　who　may　not　be　capable　of　practising　the　Photographic　art；　either　on　paper；　or　metalic　platesbut；　like　all　other　professions；　some　are　more　clever　in　its　various　processes　than　others。

Impatience　is　a　great　drawback　to　perfect　success；　and　combined　with　laziness　is　a　decided　enemy。　　Besides　this；　no　one　can　excel　in　Photography　who　does　not　possess　a　natural　taste　for　the　fine　arts；　who　is　not　quick　in　discerning　grace　and　beautyis　regardless　of　the　principles　of　perspective；　foreshorting　and　other　rules　of　drawing；　and　who　sets　about　it　merely　for　the　sake　of　gainwithout　the　least　ambition　to　rise　to　the　first　rank；　both　in　its　practice　and　theory。　There　is　no　profession　or　trade　in　which　a　slovenly　manner　will　not　show　itself；　and　none　where　its　effects　will　be　more　apparent　than　this。

In　order　to　be　great　in　any　pursuit；　we　must　be　ourselves；　and　keep　all　things；　in　order。　　In　your　show　and　reception　rooms；　let　neatness　prevail；　have　your　specimens　so　placed　leaning　slightly　forwardas　to　obtain　the　strongest　light　upon　them；　and　at　the　same　time　prevent　that　glassiness　of　apearance　which　detracts　so　materially　from　the　effect　they　are　intended　to　produce。　　If　possible；　let　the　light　be　of　a　north…western　aspect；　mellowed　by　curtains　of　a　semitransparent　hue。　Your　show…cases；　at　the　door；　should　be　kept　well　cleaned。　I　have　often　been　disgusted　while　attempting　to　examine　portraits　in　the　cases　of　our　artists；　at　the　greasy　coating　and　marks　of　dirty　fingers　upon　the　glass　and　frame　enclosing　them。　Believe　it；　many　a　good　customer　is　lost　for　no　other　reason。

In　your　operating　room；　dust　should　be　carefully　excluded。　It　should　be　furnished　with　nothing　apt　to　collect　and　retain　dust；　a　carpet　is　therefore　not　only　a　useless　article；　but　very　improper。　A　bare　floor　is　to　be　prefered；　but　if　you　must　cover　it　use　matting。　There　is　no　place　about　your　establishment　where　greater　care　should　be　taken　to　have　order　and　cleanliness；　for　it　will　prevent　many　failures　often　attributed　to　other　causes。　〃A　place　for　every　thing；　and　every　thing　in　its　place；〃　should　be　an　absolute　maxim　with　all　artists。　　Do　not　oblige　the　ladies；　on　going　away　from　your　rooms；　to　say〃That　H。　is　a　slovenly　man；　see　how　my　dress　is　ruined　by　sitting　down　in　a　chair　that　looked　as　if　it　had　just　come　out　of　a　porter　house　kitchen　and　had　not　been　cleaned　for　six　months。〃

In　choosing　your　operating　room；　obtain　one　with　a　north…western　aspect；　if　possible；　and　either　with；　or　capable　of　having　attached；　a　large　skylight。　　Good　pictures　may　be　taken　without　the　sky…light；　but　not　the　most　pleasing　or　effective。

A　very　important　point　to　be　observed；　is　to　keep　the　camera　perfectly　free　from　dust。　　The　operator　should　be　careful　to　see　that　the　slightest　particle　be　removed；　for　the　act　of　inserting　the　plate…holder　will　set　it　in　motion；　if　left；　and　cause　those　little　black　spots　on　the　plate；　by　which　an　otherwise　good　picture　is　spoiled。　　The　camera　should　be　so　placed　as　to　prevent　the　sun　shining　into　the　lenses。

In　taking　portraits；　the　conformation　of　the　sitter　should　be　minutely　studied　to　enable　you　to　place　her　or　him　in　a　position　the　most　graceful　and　easy　to　be　obtained。　　The　eyes　should　be　fixed　on　some　object　a　little　above　the　camera；　and　to　one　sidebut　never　into；　or　on　the　instrument；　as　some　direct；　the　latter　generally　gives　a　fixed；　silly；　staring；　scowling　or　painful　expression　to　the　face。　Care　should　also　be　taken；　that　the　hands　and　feet；　in　whatever　position；　are　not　too　forward　or　back　ward　from　the　face　when　that　is　in　good　focus

If　any　large　surface　of　white　is　present；　such　as　the　shirt　front；　or　lady's　handkerchief；　a　piece　of　dark　cloth　（a　temporary　bosom　of　nankeen　is　best；）　may　be　put　over　it；　but　quickly　withdrawn　when　the　process　is　about　two　thirds　finished。

A　very　pleasing　effect　is　given　to　portraits；　by　introducing；　behind　the　sitter；　an　engraving　or　other　pictureif　a　painting；　avoid　those　in　which　warm　and　glowing　tints　predominate。　The　subject　of　these　pictures　may　be　applicable　to　the　taste　or　occupation　of　the　person　whose　portrait　you　are　taking。　This　adds　much　to　the　interest　of　the　picture；　which　is　otherwise　frequently　dull；　cold　and　inanimate。

Mr。　J。　H。　Whitehurst　of　Richmond；　Va。；　has　introduced　a　revolving　background；　which　is　set　in　motion　during　the　operation；　and　produces　a　distinctness　and　boldness　in　the　image　not　otherwise　to　be　obtained。　The　effect　upon　the　background　of　the　plate　is　equally　pleasing；　it　having　the　appearance　of　a　beautifully　clouded　sky。

In　practising　Photographic　drawing　on　paper；　the　student　must　bear　in　mind　that　it　is　positively　essential；　to　secure　success　in　the　various　processes；　to　use　the　utmost　precaution　in　spreading　the　solutions；　and　washes　from　the　combination　of　which　the　sensitive　surfaces　result。　　The　same　brush　should　always　be　used　for　the　same　solution；　and　never　used　for　any　other；　and　always　washed　in　clean　water　after　having　been　employed。　Any　metalic　mounting　on　the　brushes　should　be　avoided；　as　the　metal　precipitates　the　silver　from　its　solution。　The　brushes　should　be　made　of　camels　or　badger's　hair　and　sufficiently　broad　and　large　to　cover　the　paper　in　two　or　three　sweeps；　for　if　small　ones　be　employed；　many　strokes　must　be　given；　which　leave　corresponding　streaks　that　will　become　visible　when　submitted　to　light；　and　spoil　the　picture。

These　few　preliminary　hints　and　suggestions；　will；　I　trust；　be　of　some　service　to　all　who　adopt　this　pleasing　art　as　a　profession；　and　will；　with　a　due　attention　to　the　directions　given　in　the　practical　working　of　the　Daguerreotype；　Calotype；　etc。；　ensure　a　corresponding　measure　of　success。



CHAP。　V。

DAGUERREOTYPE　APPARATUS。


The　entire　Daguerreotype　process　is　comprised　in　seven　distinct　operations；　viz：

1。Cleaning　and　polishing　the　plate。

2。Applying　the　sensitive　coating。

3Submitting　the　plate　to　the　action　of　light　in　the　camera。

4。Bringing　out　the　picture；　in　other　words　rendering　it　visible。

5。Fixing　the　image；　or　making　it　perminentso　that　the　light　may　no　longer　act　upon　it。

6。Gilding：　　or　covering　the　picture　with　a　thin　film　of　gold　which　not　only　protects　it；　but　greatly　improves　its　distinctness　and　tone　of　color。

7。Coloring　the　picture。

For　these　various　operations　the　following　articles　which　make　up　the　entire　apparatus　of　a　Daguerrean　artist　must　be　procured

1。THE　CAMERA。（Fig。　5。）。　The　Camera　Obscura　of　the　Italian　philosophers；　although　highly　appreciated；　on　account　of　the　magical　character　of　the　pictures　it　produced；　remained　little　other　than　a　scientific　toy；　until　the　discovery　of　M。　Daguerre。　The　value　of　this　instrument　is　now　great；　and　the　interest　of　the　process　which　it　so　essentially　aids；　universally　admitted。　A　full　description　of　it　will　therefore　be　interesting。　　＇hipho_5。gif＇

The　camera　is　a　dark　box　（a）；　having　a　tube　with　lenses　（b）　placed　in　one　end　of　it；　through　which　the　radiations　from　external　objects　pass；　and　form　a　diminished　picture　upon　the　ground　glass　（g）　placed　at　the　proper　distance　in　the　box　to　receive　it；　the　cap　c　covering　the　lenses　at　b　until　the　plate　is　ready　to　receive　the　image　of　the　object　to　be　copied。

Thus　a　（fig。　6。）　representing　the　lens；　and　b　the　object　desired　to　be　represented；　the　rays　（c；　c）　proceeding　from　it　fall　upon　the　lens；　and　are　transmitted　to　a　point；　which　varies　with　the　curvature　of　the　glass；　where　an　inverted　image　（d）　of　b　is　very　accurately　formed。　At　this　point；　termed　the　focus；　the　sensitive　photographic　material　is　placed　for　the　purpose　of　obtaining　the　required　picture。

The　great　disideratum　in　a　photographic　camera　is　perfect　lenses。　They　should　be　achromatic；　and　the　utmost　　＇hipho_6。gif＇　transparency　should　be　obtained；　and　under　the　closest　inspection　of　the　glass　not　the　slightest　wavy　appearance；　or　dark　spot　should　be　detected；　and　a　curvature　which　as　much　as　possible　prevents　spherical　aberration　should　be　secured。　The　effect　produced　by　this　last　defect　is　a　convergence　of　perpendiculars；　as　for　instance；　two　towers　of　any　building；　would　be　represented　as　leaning　towards　each　other；　and　in　a　portrait　the　features　would　seem　contracted；　distorted　and　mingled　together；　so　as　to　throw　the　picture　out　of　drawing　and　make　it　look　more　like　a　caricature　than　a　likeness。　If　the　lens　be　not　achromatic；　a　chromatic　aberration　takes　place；　which　produces　an　indistinct；　hazy　appearance　around　the　edges　of　the　picture；　arising　from　the　blending　of　the　rays。

The　diameter　and　focal　length　of　a　lens　must　depend　in　a　great　measure　on　the　distance　of　the　object；　and　also　on　the　superficies　of　the　plate　or　paper　to　be　covered。　　For　portraits　one　of　1　1/2　inches　diameter；　and　from　4　1/2　to　5　1/2　inches　focus　may　be　used；　but　for　distant　views；　one　from　2　inches　to　3　inches　diameter；　and　from　8　to　12　inches　focal　length　will　answer　much　better。　　For　single　le