essays-1-第62部分

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wood；　or　turf；　as　well　as　those　constructed　for　burning　coals。

CHAPTER。　II。　　Practical　directions　designed　for　the　use　of　workmen；　showing　　　　how　they　are　to　proceed　in　making　the　alterations　necessary　to　　　　improve　chimney　fire…places；　and　effectually　to　cure　smoking　　　　chimnies。

CHAPTER。　III。　　Of　the　cause　of　the　ascent　of　smoke。　　Illustration　of　the　subject　by　familiar　comparisons　and　　　　experiments。　　Of　chimnies　which　affect　and　cause　each　other　to　smoke。　　Of　chimnies　which　smoke　from　want　of　air。　　Of　the　eddies　of　wind　which　sometimes　blow　down　chimnies；　　　　and　cause　them　to　smoke。　　Explanation　of　the　figures。


ESSAY　IV。

ADVERTISEMENT

The　Author　thinks　it　his　duty　to　explain　the　reasons　which　have　induced　him　to　change　the　order　in　which　the　publication　of　his　Essays　has　been　announced　to　the　Public。Being　suddenly　called　upon　to　send　to　Edinburgh　a　person　acquainted　with　the　method　of　altering　Chimney　Fire…places；　which　has　lately　been　carried　into　execution　in　a　number　of　houses　in　London；　in　order　to　introduce　these　improvements　in　Scotland；　he　did　not　think　it　prudent　to　send　any　person　on　so　important　an　errand　without　more　ample　instruction　than　could　well　be　given　verbally；　and　being　obliged　to　write　on　the　subject；　he　thought　it　best　to　investigate　the　matter　thoroughly；　and　to　publish　such　particular　directions　respecting　the　improvements　in　question　as　may　be　sufficient　to　enable　all　those；　who　may　be　desirous　of　adopting　them；　to　make；　or　direct　the　necessary　alterations　in　their　Fire…places　without　any　further　assistance。

The　following　Letter；　which　the　Author　received　from　Sir　John　Sinclair；　Baronet；　Member　of　Parliament；　and　President　of　the　Board　of　Agriculture；　will　explain　this　matter　more　fully：

You　will　hear　with　pleasure　that　your　mode　of　altering　Chimnies；　so　as　to　prevent　their　smoking；　to　save　fuel；　and　to　augment　heat；　has　answered　not　only　with　me；　but　with　many　of　my　friends　who　have　tried　it；　and　that　the　Lord　Provest　and　Magistrates　of　Edinburgh　have　voted　a　sum　of　money　to　defray　the　expences　of　a　bricklayer；　who　is　to　be　sent　there　for　the　purpose　of　establishing　the　same　plan　in　that　city。　　I　hope　that　you　will　have　the　goodness　to　expedite　your　paper　upon　the　management　of　Heat；　that　the　knowledge　of　so　useful　an　art　may　be　as　rapidly　and　as　extensively　diffused　as　possible。With　my　best　wishes　for　your　success　in　the　various　important　pursuits　in　which　you　are　now　engaged；　believe　me；　with　great　truth　and　regard；　　　　　　　　　　　Your　faithful　and　obedient　servant　　　　　　　　　　　　　　　　　　　　　　　　　　　　　John　Sinclair　Whitehall；　London；　9th　February　1796。


CHAPTER。　I。

　Fire…places　for　burning　coals；　or　wood；　in　an　open　chimney；　　　　are　capable　of　great　improvement。　　Smoking　chimnies　may　in　all　cases　be　completely　cured。　　The　immoderate　size　of　the　throats　of　chimnies　the　principal　　　　cause　of　all　their　imperfections。　　Philosophical　investigation　of　the　subject。　　Remedies　proposed　for　all　the　defects　that　have　been　discovered　　　　in　chimnies　and　their　open　fire…places。　　These　remedies　applicable　to　chimnies　destined　for　burning　　　　wood；　or　turf；　as　well　as　those　constructed　for　burning　coals。

The　plague　of　a　smoking　Chimney　is　proverbial；　but　there　are　many　other　very　great　defects　in　open　Fire…places；　as　they　are　now　commonly　constructed　in　this　country；　and　indeed　throughout　Europe；　which；　being　less　obvious；　are　seldom　attended　to；　and　there　are　some　of　them　very　fatal　in　their　consequences　to　health；　and；　I　am　persuaded；　cost　the　lives　of　thousands　every　year　in　this　island。

Those　cold　and　chilling　draughts　of　air　on　one　side　of　the　body；　while　the　other　side　is　scorched　by　a　Chimney　Fire；　which　every　one　who　reads　this　must　often　have　felt；　cannot　but　be　highly　detrimental　to　health；　and　in　weak　and　delicate　constitutions　must　often　produce　the　most　fatal　effects。I　have　not　a　doubt　in　my　own　mind　that　thousands　die　in　this　country　every　year　of　consumptions　occasioned　solely　by　this　cause。By　a　cause　which　might　be　so　easily　removed！by　a　cause　whose　removal　would　tend　to　promote　comfort　and　convenience　in　so　many　ways。

Strongly　impressed　as　my　mind　is　with　the　importance　of　this　subject；　it　is　not　possible　for　me　to　remain　silent。The　subject　is　too　nearly　connected　with　many　of　the　most　essential　enjoyments　of　life　not　to　be　highly　interesting　to　all　those　who　feel　pleasure　in　promoting；　or　in　contemplating　the　comfort　and　happiness　of　mankind。And　without　suffering　myself　to　be　deterred；　either　by　the　fear　of　being　thought　to　give　the　subject　a　degree　of　importance　to　which　it　is　not　entitled；　or　by　the　apprehension　of　being　tiresome　to　my　readers　by　the　prolixity　of　my　descriptions；I　shall　proceed　to　investigate　the　subject　in　all　its　parts　and　details　with　the　utmost　care　and　attention。　And　first　with　regard　to　smoking　Chimnies：

There　are　various　causes　by　which　Chimnies　may　be　prevented　from　carrying　smoke；　but　there　are　none　that　may　not　easily　be　discovered　and　completely　removed。This　will　doubtless　be　considered　as　a　bold　assertion；　but　I　trust　I　shall　be　able　to　make　it　appear　in　a　manner　perfectly　satisfactory　to　my　readers　that　I　have　not　ventured　to　give　this　opinion　but　upon　good　and　sufficient　grounds。

Those　who　will　take　the　trouble　to　consider　the　nature　and　properties　of　elastic　fluids；of　air；smoke；and　vapour；　and　to　examine　the　laws　of　their　motions；　and　the　necessary　consequences　of　their　being　rarified　by　heat；　will　perceive　that　it　would　be　as　much　a　miracle　if　smoke　should　not　rise　in　a　Chimney；　（all　hindrances　to　its　ascent　being　removed；）　as　that　water　should　refuse　to　run　in　a　syphon；　or　to　descend　in　a　river。

The　whole　mystery；　therefore；　of　curing　smoking　Chimnies　is　comprised　in　this　simple　direction。　　FIND　OUT　AND　REMOVE　THOSE　LOCAL　HINDRANCES　WHICH　FORCIBLY　PREVENT　THE　SMOKE　FROM　FOLLOWING　ITS　NATURAL　TENDENCY　TO　GO　UP　THE　CHIMNEY；　or　rather；　to　speak　more　accurately；　which　prevents　its　being　forced　up　the　Chimney　by　the　pressure　of　the　heavier　air　of　the　room。

Although　the　causes；　by　which　the　ascent　of　smoke　in　a　Chimney　MAY　BE　obstructed；　are　various；　yet　that　cause　which　will　most　commonly；　and　I　may　say　almost　universally　be　found　to　operate；　is　one　which　it　is　always　very　easy　to　discover；　and　as　easy　to　remove；the　bad　construction　of　the　Chimney　IN　THE　NEIGHBOURHOOD　OF　THE　FIRE…PLACE。

In　the　course　all　my　experience　and　practice　in　curing　smoking　Chimnies；and　I　certainly　have　not　had　less　than　five　hundred　under　my　hands；　and　among　them　many　which　were　thought　to　be　quite　incurable；I　have　never　been　obliged；　except　in　one　single　instance；　to　have　recourse　to　any　other　method　of　cure　than　merely　reducing　the　Fire…place　and　the　throat　of　the　Chimney；　or　that　part　of　it　which　lies　immediately　above　the　Fire…place；　to　a　proper　form；　and　just　dimensions。

That　my　principles　for　constructing　Fire…places　are　equally　applicable　to　those　which　are　designed　for　burning　coal；　as　to　those　in　which　wood　is　burnt；　has　lately　been　abundantly　proved　by　experiments　made　here　in　London；　for　of　above　an　hundred　and　fifty　Fire…places　which　have　been　altered　in　this　city；　under　my　direction；　within　these　last　two　months；　there　is　not　one　which　ha