essays-1-第49章

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ed　from　the　middle　of　the　upper　part　of　the　breast　of　the　Chimney　falls。　　The　situation　for　the　new　back　is　ascertained　by　taking　the　line　e　f　equal　to　four　inches。　The　new　back　and　covings　are　represented　as　being　built　of　bricks；and　the　space　between　these　and　the　old　back　and　covings　as　being　filled　up　with　rubbish。　　See　page　342。

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Fig。　4。　This　Figure　represents　the　elevation　or　front　view　of　the　Fire…place　Fig。　3。　after　it　has　been　altered。　　The　lower　part　of　the　door…way　left　for　the　Chimney…sweeper　is　shown　in　this　Figure　by　white　dotted　lines。　　See　page　344。

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Fig。　5。　This　Figure　shows　the　section　of　a　Chimney　Fire…place　and　of　a　part　of　the　canal　of　the　Chimney；　on　the　common　construction。

a　b　is　the　opening　in　front；　b　c；　the　depth　of　the　Fire…place　at　the　hearth；　d；　the　breast　of　the　Chimney。

d　e；　the　throat　of　the　Chimney；　and　d　f；　g　e；　a　part　of　the　open　canal　of　the　Chimney。

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Fig。　6。　Shows　a　section　of　the　same　Chimney　after　it　has　been　altered。

k　l　is　the　new　back　of　the　Fire…place；　l　i；　the　tile　or　stone　which　closes　the　door…way　for　the　Chimney…sweeper；　d　i；　the　throat　of　the　Chimney；　narrow　to　four　inches；　a；　the　mantle；　and　h；　the　new　wall　made　under　the　mantle　to　diminish　the　height　of　the　opening　of　the　Fire…place　in　front。

N。B。　These　two　Figures　are　sections　of　the　same　Chimney　which　is　represented　in　each　of　the　four　preceding　Figures。

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Fig。　7。

This　Figure　represents　the　ground　plan　of　a　Chimney　Fire…place　in　which　the　grate　is　placed　in　a　niche；　and　in　which　the　original　width　A　B　of　the　Fire…place　is　considerably　diminished。

a　b　is　the　opening　of　the　Fire…place　in　front　after　it　has　been　altered；　and　d　is　the　back　of　the　niche　in　which　the　grate　is　placed。　See　page　347。

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Fig。　8。　Shows　a　front　view　of　the　same　Fire…place　after　it　has　been　altered；　where　may　be　seen　the　grate；　and　the　door…way　for　the　Chimney…sweeper。　See　page　347。

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Fig。　9。　Shows　a　section　of　the　same　Fire…place；　c　d　e　being　a　section　of　the　niche；　g　the　door…way　for　the　Chimney…sweeper；　closed　by　a　piece　of　the　fire…stone；　and　f　the　new　wall　under　the　mantle　by　which　the　height　of　the　opening　of　the　Fire…place　in　front　is　diminished。　See　page　347。

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Fig。　10。　This　Figure　shows　how　the　covings　are　to　be　placed　when　the　front　of　the　covings　（a　and　b）　do　not　come　so　far　forward　as　the　front　of　the　opening　of　the　Fire…place；　or　the　jambs　（A　and　B）。　See　page　348。

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Fig。　11。　This　Figure　shows　how　the　width　and　obliquity　of　the　covings　are　to　be　accommodated　to　the　width　of　the　back　of　a　Fire…place；　in　cases　where　it　is　necessary　to　make　the　back　very　wide。　See　page　349。

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Fig。　12。　This　Figure　shows　how　an　instrument　called　a　bevel　（m　n）；　useful　in　laying　out　the　work；　in　altering　Chimney　Fire…places；　may　be　constructed。　See　page　349。

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Fig。　13。　This　shows　how；　when　the　breast　of　a　Chimney　（d）　is　too　high；　it　may　be　brought　down　by　means　of　a　wall　（h）　placed　under　the　mantle；　and　a　coating　of　plaster；　which　in　this　Figure　is　represented　by　the　part　marked　by　dots。　See　page　351。

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Fig。　14。　This　shows　how　the　breast　of　a　Chimney　may　be　brought　down　merely　by　a　coating　of　plaster。　See　page　351。


Footnotes　for　essay　IV。

＇1＇　Eves　and　Sutton；　bricklayers；　Broad　Sanctuary；　Westminster；　have　alone　altered　above　90　Chimnies。The　experiment　was　first　made　in　London　at　Lord　Palmerston's　house　in　Hanover…square；then　two　Chimnies　were　altered　in　the　house　of　Sir　John　Sinclair；　Baronet；　President　of　the　Board　of　Agriculture；　one　in　the　room　in　which　the　Board　meets；　and　the　other　in　the　Secretary's　room；　which　last　being　much　frequented　by　persons　from　all　parts　of　Great　Britain；　it　was　hoped　that　circumstances　would　tend　much　to　expedite　the　introduction　of　these　improvements　in　various　parts　of　the　kingdom。　　Several　Chimnies　were　altered　in　the　house　of　Sir　Joseph　Banks；　Baronet；　K。　B。　President　of　the　Royal　Society。　Afterwards　a　number　were　altered　in　Devonshire…house；in　the　house　of　Earl　Besborough；　in　Cavendish…square；　and　at　his　seat　at　Roehampton；at　Holywell…house；　near　St。　Alban's；　the　seat　of　the　Countess　Dowager　Spencer：at　Melbourne…house；at　Lady　Templeton's　in　Portland…place；　at　Mrs　Montagu's　in　Portman…square；　at　Lord　Sudley's；　in　Dover…street：at　the　Marquis　of　Salisbury's　seat　at　Hatfield；　and　at　his　house　in　town；at　Lord　Palmerston's　seat　at　Broadlands；　near　Southampton；　and　at　several　gentlemen's　houses　in　that　neighbourhood；and　a　great　many　others；　but　it　would　be　tiresome　to　enumerate　them　all；　and　even　these　are　mentioned　merely　for　the　satisfaction　of　those　who　may　wish　to　make　inquiries　respecting　the　success　of　the　experiments。

＇2＇　Having　been　obliged　to　carry　backward　the　Fire…place　in　the　manner　here　described；　in　order　to　accommodate　it　to　a　Chimney　whose　walls　in　front　were　remarkably　thin；I　was　surprised　to　find　upon　lighting　the　fire　that　it　appeared　to　give　out　more　heat　into　the　room　than　any　Fire…place　I　had　ever　constructed。　This　effect　was　quite　unexpected；　but　the　cause　of　it　was　too　obvious　not　to　be　immediately　discovered。The　flame　rising　from　the　fire　broke　against　the　part　of　the　back　which　sloped　forward　over　the　fire；　and　this　part　of　the　back　being　soon　very　much　heated；　and　in　consequence　of　its　being　very　hot；　（and　when　the　fire　burnt　bright　it　was　frequently　quite　red　hot；）　it　threw　off　into　the　room　a　great　deal　of　radiant　heat。It　is　not　possible　that　this　oblique　surface　（the　slope　of　the　back　of　the　Fire…place）　could　have　been　heated　red…hot　MERELY　by　the　radiant　heat　projected　by　the　burning　fuel；　for　other　parts　of　the　Fire…place　nearer　the　fire；　and　better　situated　for　receiving　radiant　heat；　were　never　found　to　be　so　much　heated；and　hence　it　appears　that　the　combined　heat　in　the　current　of　smoke　and　hot　vapour　which　rises　from　an　open　fire　MAY　BE；　at　least　IN　PART；　stopped　in　its　passage　up　the　Chimney；　changing　into　radiant　heat；　and　afterwards　thrown　into　the　room。This　opens　up　a　new　and　very　interesting　field　for　experiment；　and　bids　fair　to　lead　to　important　improvements　in　the　construction　of　Fire…places。I　have　of　late　been　much　engaged　in　these　investigations；　and　am　now　actually　employed　daily　in　making　a　variety　of　experiments　with　grates　and　Fire…places；　upon　different　constructions；　in　the　room　I　inhabit　in　the　Royal　Hotel　in　Pall　Mall；and　Mr。　Hopkins　of　Greek…street　Soho；　Ironmonger　to　his　Majesty；　and　Mrs。　Hempel；　at　her　Pottery　at　Chelsea；　are　both　at　work　in　their　different　lines　of　business；　under　my　direction；　in　the　construction　of　Fire…places　upon　a　principle　entirely　new；　and　which；　I　flatter　myself；　will　be　found　to　be　not　only　elegant　and　convenient；　but　very　economical。But　as　I　mean　soon　to　publish　a　particular　account　of　these　Fire…places；with　drawings　and　ample　directions　for　constructing　them；　I　shall　not　enlarge　farther　on　the　subject　in　this　place。It　may　however　not　be　amiss　just　to　mention　here；　that　these　new…invented　Fire…places　not　being　fixed　to　the　walls　of　the　Chimney；　but　merely　set　down　upon　the　hearth；　may　be　used　in　any　open　Chimney：　and　that　Chimnies　altered　or　constructed　on　the　principles　here　recommended　are　particularly　well　adapted　for　receiving　them。

The　Public　in　general；　and　more　particularly　those　Tradesmen　and　Manufacturers　whom　it　may　concern；　are　requested　to　observe；　that　as　the　Author　does　not　intent　to　take　out　himself；　or　to　suffer　others　to　take　out；　any　patent　for　any　invention　of　his　which　may　be　of　public　utility；　all　persons　are　at　full　liberty　to　imitate　them；　and　vend　them；　for　their　own　emolument；　when　and　where；　and　in　any　way　they　may　think　proper；　and　those　who　may　wish　for　any　further　information　respecting　any　of　those　inventions　or　improvements　will　receive　（gratis）　all　the　information　they　can　require　by　applying　to　the　Author；　who　will　take　pleasure　in　giving　them　every　assistance　in　his　power。

＇3＇　Kindling　balls　composed　of　equal　parts　of　coal；charcoal；　and　clay；　the　two　former　reduced　to　a　fine　powder；　well　mixed　and　kneaded　together　with　the　clay　moistened　with　water；　and　then　formed　into　balls　of　the　size　of　hens　eggs；　and　thoroughly　dried；　might　be　used　with　great　advantage　instead　of　wood　for　kindling　fires。　　These　kindling　balls　may　be　made　so　inflammable　as　to　take　fire　in　an　instant　and　with　the　smallest　spark；　by　dipping　them　in　a　strong　solution　of　nitre　and　then　drying　them　again；　and　they　would　neither　be　expensive　nor　liable　to　be　spoiled　by　long　keeping。　　Perhaps　a　quantity　of　pure　charcoal　reduced　to　a　very　fine　powder　and　mixed　with　the　solution　of　nitre　in　which　they　are　dipped　would　render　them　still　more　inflammable。

I　have　often　wondered　that　no　attempts　should　have　been　made　to　improve　the　fires　which　are　made　in　the　open　Chimnies　of　elegant　apartments；　by　preparing　the　fuel；　for　nothing　surely　was　ever　more　dirty；　inelegant；　and　disgusting　than　a　common　coal　fire。

Fire　balls　of　the　size　of　goose　eggs；　composed　of　coal　and　charcoal　in　powder；　mixed　up　with　a　due　proportion　of　wet　clay；　and　well　dried；　would　make　a　much　more　cleanly；　and　in　all　respects　a　pleasanter　fire　than　can　be　made　with　crude　coals；　and　I　believe　would　not　be　more　expensive　fuel。　　In　Flanders　and　in　several　parts　of　Germany；　and　particular　in　the　Dutchies　of　Juliers　and　Bergen；　where　coals　are　used　as　fuel；　the　coals　are　always　prepared　before　they　are　used；　by　pounding　them　to　a　powder；　and　mixing　them　up　with　an　equal　weight　of　clay；　and　sufficient　quantity　of　water　to　form　the　whole　into　a　mass　which　is　kneaded　together　and　formed　into　cakes；　which　cakes　are　afterwards　well　dried　and　kept　in　a　dry　place　for　use。　And　it　has　been　found　by　long　experience　that　the　expense　attending　this　preparation　is　amply　repaid　by　the　improvement　of　the　fuel。　　The　coals；　thus　mixed　with　the　clay；　not　only　burn　longer；　but　give　much　more　heat　than　when　they　are　burnt　in　their　crude　state。

It　will　doubtless　appear　extraordinary　to　those　who　have　not　considered　the　subject　with　some　attention；　that　the　quantity　of　heat　produced　in　the　combustion　of　any　quantity　of　coals　should　be　increased　by　mixing　the　coals　with　clay；　which　is　certainly　an　incombustible　body；but　the　phenomenon　may；　I　think；　be　explained　in　a　satisfactory　manner。

The　heat　generated　in　the　combustion　of　any　small　particle　of　coal　existing　under　two　distinct　forms；　namely；　in　that　which　is　COMBINED　with　the　flame　and　smoke　which　rise　from　the　fire；　and　which　if　means　are　not　found　to　stop　it；　goes　off　immediately　by　the　Chimney　and　is　lost；and　the　RADIANT　HEAT　which　is　sent　off　from　the　fire；　in　all　directions　in　right　lines：I　think　it　reasonable　to　conclude；　that　the　particles　of　clay　which　are　surrounded　on　all　sides　by　the　flame　arrest　a　part　at　least　of　the　combined　heat；　and　prevent　its　escape；　and　this　combined　heat；　so　arrested；　heating　the　clay　red　hot；　is　retained　in　it；　and　being　changed　by　this　operation　to　radiant　heat；　is　afterwards　emitted；　and　may　be　directed；　and　employed　to　useful　purposes。

In　composing　fire　balls；　I　think　it　probable　that　a　certain　proportion　of　chaffof　straw　cut　very　fine；　or　even　saw　dust；　might　be　employed　with　great　advantage。　　I　wish　those　who　have　leisure　would　turn　their　th