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w rong pofition of the honre wi th regard to extern,d ob·
j c:~ls. which. by interrupting Ihe cou rre o( Ihe alT, m<l.kes
H aljjune vanous dir~ét.ons. and whc:.:l abou t In eddics. fa iI.!
t o prl.!'r ent il frvOl ¡¡ (cc oJing wlth CAre from lhe clllmney
10p, or bcltSH do\Vn ioto lhe room wlth violcnce T hls is
n!Ofc 1~IJum dle cauCe of rm ,ky houf~s thlO eilher of die
t \Vo bl!fore mt:ntioncd; although le fccms:o bl! almaH lhe onl y
OOI! auen,!ed to ~y lhe perfons who prctcnd tO Cure fmoky
hou fes dl pr-:(enr, ;\s ml,}{t of cheir reml!dic:s :He adapten 10
rcmovt! lhe diliJrders uifing from Ihis caufe alone. \Ve
(h ,dl bri.!tly POtnt out lhe (everal cil.fes in ",hich this can oc–
CUT. Ihac every ane rn.l.y be enabled to judge for hLmfdf
wh:..n thele cures are proper or noto
1~ne .liT (as htis been ) is a fl'l id, aAn wind a cu rrent
ofth,\[ flll ,d; which, when driveo along the fu rface of (he
eClnh. flows with a fmooth ;lnd equal Iheam, unlefs when
oppofed by fome oojea: which Interrupts ilS courfe : but
wncn iI meets with any ohjtCl whlch dirtc9: ly oppofes ItS
CanTre, i1 is io fome me;¡(uT¡ pufhed b,lck ag tln and m<lde
10 fpread on every fide, til! it m~~ts with fome apeo (jde:, to·
wards which tI Jlo\Vs with great impetuoGty. lt is hkewife
a fl uid of conliderable gravity , aod thercfore prdrt:s upon
the furface of the eanh with great force; fa that, wilen a
current oEit flows along lhe furrace of our globe, il has a
tendency (O move forwcHd and prefs dOlYnward It tlle
f:lIne time : (rom when¡;e il happens, lhat when :lo cu rrent of
. air is (oreeo ova the top of aoy higl. objett. the.: fide of which
def..:ends perp::ndiculady do.vnw",d, the VelOClty of the
currcnt al nrll overcomes Ihe gravity, and it fiies a {hort way
over in 1hitt oireétion¡ but lhe power of gr.nilY aain ~ up'
on lhe ooJ er fur face , d.aws it downward and in a fllOrt
time overcomcs the impetus that ir had 10 ruOl forward, and
oc.:afions a (on of eddy oe~rly fimilar ro wlut W~ (t:e a,.
water behind a none which interrupls rhe violence of
its currtnLS.
To illullrate this rAore plaioly. let AB. fig . 1{2'. rep rerent
~ p ln of a high ouilding. netir to wbich is a frn aller one
CD j and I: t lhe dotted line EF reprefent a currelll of alr
B~)'N'ing with conridt::rable force in the direétion FE lt is
pl ain that it will flow rlraight rorward over the rop of the
f:nal1 buildiílg ; but when il meets with the large objl:él, ir
\'1111 be ilHerrupled in its cour(e, ~nd fpread itflllf on every
fiJ e, as rc~refented by the dotled lines GG &c. ~t Idll it
\'Ji!1 no .v towards tha[ place through which it can efcd,pe
,.ith the greatell eafe . (f the oppoliog objeé! be large, and
h~s no opl!ning lhrough which il can ,(fue near lhe grCound,
lhe n it wtll afc.c:nJ tO lhe rop of it, and flow off in rhar di·
rettiun, Cdflyiog the fllloke whi::h afcends from the fmall
chimney e alonJ.t with it : but if there is aoy openlng be·
Jow, either a fire:et or laoe, or any other p~,rdge thal \ViII
admlt lhe wind tO pafs , then will lhe natural gravity of the
air dra'v the general currcot 10 flow olF through
lhe bwcr p l(j:tge~ in wt- ich care, lhe fmoke which OUgh l tO
;¡(cend. th rough II!e chimney e, meeting with a currcnl of
O\ir oppofing HS paOdgc, will nOL be at liberty 10 i(fue
(ortll, bm be rorcc:J b<l\. k ar,ain iota the room from whence
il pro-:c:'e:u, unlc:fs fome contrivaoce is falJco upon tO pre·
v: nt ir.
Ar.ain, let A, fi g 13 . reprefent a fmall builJing at the
fide o" a grcat rock B, and the wind co;ning In the din·éllUn
e D ; when the currera of air comes to the: poior D , bc.:ing
hurri..:d forw.ard \Vi lh grettt VclOClty, it gocs a lilde. tClrWJTJ,
b Ul fooo ¿<fecods dow,ward. aod gradu.lly ;. r.::B<atd lIlore
612 S 1\1 O
and more inward, as. repre:lcmed by the dotted lines E E,
&c ro thJt, ddccnJlOg uown ....'drJs UpUII lile lOp I,)f the duro.
~~y A ~ the Imokt: ., ~t::dt b,lo::k ag.tln into the OljH.rtm:.:s.
1;¡~S It IS lh,H low Iloul~s, when contiguJl1s (O hl¡:h cbjtéh,
are 10 danger 01 uelOg d,llurv..:d with 10101\:>! . Ir lhe conti–
gllOUS obJld,t He 001 vcry hlgh, lhl.! dlfolder mAy be·, ur~d
by he.·lghtC01Ag the ..:hlmn~y of th~ low houfe . but ¡nI i.
vcry IlIgh . 11 wllI be nccdrclTy t.J CQve.:r Ihe tor of lhe chlm–
~ey 10 mallne r a, 10 prcveot the Wlnd from enteflng
lt, at lh e: t(l111': ttml! th,H :.t pa(f-tg~ is lert al fo!uc 01 the
fides throl1gh whl\;h lhe (ruokt: 1l1,'y ¡{rue Wilh freedom, l\.rae
ny ...re (he conUlfaOCts whlch h ... ve beeo invented for {his
purpo(e, whi",'l Me la bt; me:t wl' h ~very wherej and;,¡s there
¡s. no dliticul ty In acc!lmpilfhlng lhe defircd end by .. o 106-
olle Vtl.r!ety uf medlOds, every one who needs fuch a thing
m.l.y ple.are hls own f.locy iD ,he choice. W t:: have thouoht
ir l1nnt::ce(f'~tTy te .dd d,oy more but one: kind ofthefe, fig. ~4'
whlc~ \~i11 ",,(wer tbe end dfcélually.
lt is cvideot {hat bl)ul'es tituated ne:ar high hills, or thick
wooJs, will be: 10 (ome me"fure cxpofed 10 lhe [ame incoo.
venlence ; a ut il is Itkewife pIJio, that if a houfe be fituated
UpOll the Dope of a hiH, as at F, fig. 13. it wil! DOt be in
aoy daoger of rmok~ wheo the wiod blows lowards th~l fide:
of lhe hilJ upoo which it is fi tGated ; for the current of air
coming over rhe houfe-top In the direltiQo G H, ¡s ¡mme–
d.. ,ely changed by 'ht fI.lpe of ,he hill to the dircé!ioo He.
which powerfully J rClws lhe Imoke upward from lhe top of
lhe: chimnl!Y. Hut it is alfo eVIUeot, IhOlt a houfe in (his
fi tudtion will be Ji"ble to Imoke when che wind blows [rol.
lhe hall : for lhe current or ai r cOOling downward in the di–
reé'hon e H, W1Jl bcat dllwllward on the chuTllley F, and
prevent lhe fmoke from afcenulng with freedo m. But the
effc.:~t \ViII t e much helghteQ~d, if the door5 and wlndowl
are chl(:fi)' in ¡he Jowel'llloft fide: of the houre.
Thde: fome of lhe mon general circumUances which
preveO{ (he fre~ .tf¡;eOl uf Imokc:, anfing from extern al ob–
jeas : bUl there are many mher lerre r caults which Rlay at
times oc~afion fllloke, al) of which it would be tc:dlous here
te c:oUfTIc:rale; fuch as, blaUs 01 air, reB.~8ed from the lides
of mOUllt.tIOS, and comlog dlJwn vd lJeys with gre,\[ impc:-t u–
o{ity, occaliúnlog, in paruculttr tituatlons, eddles or whi rl–
wlIlds ot ddfaent rons . lo Ihon, 10 any mea–
rure d¡f~urbs the free motion or the ..ir, 15 10 dange r of pro..
ducing fuJden gulls. which may oce," 'o fmoke. T here–
fore, whoeve:r bullos in a ¡itu.ttlon whlch is nOl altogetber
free, may lay hls ac~ount wlth hanng fome fudden guHs of
(m~lke, uolds he rorms {he top of his chilnfley fa as to ob..
viate ie. And thc::re are lome tituations fo O1uch eKpu(ed to
fudoen gulls of wlnd, rometimes whirl,o.; round, lomertJues
!:-eat 1'u~ldt'nly Jownw.trd, or as fuJJenly c:.trned up ¡¡g"io.
th at il is dtfli..:ul t 10 gUdrd ag...lnfl e\'ay ddogcr. In the(e
fi lUOltions \Ve: would rt',:olliln~nd lom~thiog of (he farOl of
what is rc pTc:f~Ol~d at fig. J. S. which would be proot Olgouna:
evcry wl nd wh ¡lenr .
HA.viog lhllS tf.lcl"d rhe cauf.:s of fm nky houft's, Anll ree
duce:d tI'~m to di(h ol.'t c!",r~;i for lhe f3k~ ¡)f ddhn..:lllds; it
is oe:..:dr"ry. bdore \Ve ql\l~ th,s fubj~'~, tO r,bl~n ".', lh.u so
n1.\oy ..s. two or mUle (It ther.; may b~ cUIl1~:n\.·d hl aug·
ment (he lfI:d.1dy, and t1ler\!rvl'-:: it is ncedr.l r)' to lu \'r.. . 11
tht:~ ..:.:s 10 \'¡C \V 10 ew:ry PoHucul..r cli'e. It 110'"
(lnly rl'm;,ios thdt \Ve: p·)int OUt lil " ;~v I JI :,hc"'om~;'I.. \~ hll'h
Ol-tY kAd us to diflinguirh froOl wluch oE lhl!fe genl':r,d ¡;.1U–
fes the ddurJer oomrl.;Il,J of may proeced, -'''nd.
di,