,,gas ,,& ,,oil ,,eng9es    ,,simply    
,,expla9$    ,an ,elem5t>y ,in/ruction  
,book = ,amateurs   & ,eng9e ,att5dants 
,,by   ,,walt] ,c4 ,,runciman           
,,fully ,,illu/rat$     ,,london        
,model ,eng9e] ,s]ies4 ,! ,model ,eng9e]
   ,s]ies1 no4 #bf4    #aije            
,,cont5ts    ,,*ap4                     
,,page          ,,preface               
#e        ,i4 ,,introductory            
#g      ,,ii4 ,,! ,,compon5t ,,p>ts ,,( 
,,an ,,eng9e                 #ac        
,,iii4 ,,h[ ,a ,,gas ,,eng9e ,,works    
#bb      ,,iv4 ,,ignition ,,devices     
#cc       ,v4 ,,magneto ,,ignition      
#dg      ,,vi4 ,,gov]n+                 
#ea     ,,vii4 ,,cams ,,& ,,valve       
,,sett+s                          #fc   
,,viii4 ,,oil ,,eng9es                  
#ha     ,,preface   ,my object 9 plac+  
?is h&book be=e ! read] is to provide   
him ) a simple & /raight=w>d explanation
 ( h[ & :y a gas eng9e1 or an oil eng9e1
 works4 ,! ma9 features & peculi>ities 9
 ! con/ruction ( ^! eng9es are describ$1

 :ile ! me?ods & precautions necess>y to
 arrive at desirable results are detail$
 z fully z ! limit$ space p]mits4 ,i h  
aim$ at supply+ j t in=mation :i* my    
exp]i5ce %[s is mo/ ne$$ by ! us] & by !
 amateur build] ( small p[] eng9es4 ,9  
place ( giv+ a m]e li/ ( common eng9e   
tr\bles & _! rem$ies1 ,i h ?\ght x bett]
 to endeav\r to expla9 ?or\ghly !       
fundam5tal pr9ciples & ess5tials ( good 
runn+1 s t %\ld any difficulty arise1 ! 
eng9e att5dant w be able to reason out =
 himself ! cause ( ! tr\ble1 & w ?us "k 
! prop] rem$y to apply4 ,?is w give him 
a comm& ov] 8 eng9e :i* %\ld r5d] him   
equal to any em]g5cy4    ,,walt] ,c4    
,,runciman4    ,,london1 ,e4,c4         
,,gas ,,& ,,oil ,,eng9es  ,,simply      
,,expla9$     ,,*apt] ,i  ,,introductory
   ,! hi/ory ( ! gas eng9e goes back a  
long way1 & ! hi/ory ( ! int]nal        
combu/ion eng9e prop] fur!r /ill4 ,x w  
be int]e/+ to rec\nt ! ma9 po9ts 9 !    
hi/ory ( ! developm5t ( ! class ( eng9e 
we %all deal ) 9 ! foll[+ pages1 9 ord] 

to %[ :at huge /rides 7 made soon aft] !
 correct & mo/ workable !ory _h be5     
=mulat$4  ,9 #afgh ,abbe ,hautefeuille  
expla9$ h[ a ma*9e c\ld be con/ruct$ to 
"w ) gunp[d] z fuel4 ,8 arrangem5t 0 to 
explode ! gunp[d] 9 a clos$ vessel      
provid$ ) valves1 & cool ! products (   
combu/ion1 & s cause a p>tial vacuum to 
be =m$4 ,by ! aid ( su* a ma*9e1 wat]   
c\ld be rais$4 ,?is inv5tor1 h[ev]1 does
 n seem to h c>ri$ out any exp]im5ts4   
,9 #afhe ,huygh5s design$ ano!r p[d]    
ma*9e2 & ,pap91 9 #afhh1 describ$ a     
simil> ma*9e1 :i* 0 provid$ ) regul>    
valves1 z devis$ by himself1 9 !        
,proce$+s ( ! ,leipsic ,academy1 #afhh4 
,f ?is "t until #agia1 :5 ,john ,b>b]   
took out a pat5t = ! production ( =ce by
 ! combu/ion ( hydroc>bon 9 air1        
practically no advancem5t 0 made4 ,!    
latt] pat5t1 curi\sly en\gh1 compris$ a 
v primitive =m ( rot>y eng9e4 ,b>b]     
propos$ to turn coal1 oil1 or o!r       
combu/ible /uff into gas by means (     
ext]nal fir+1 & !n to mix ! gases s     

produc$ ) air 9 a vessel call$ !        
explod]4 ,?is mixture 0 !n ignit$ z x   
issu$ f ! vessel1 & ! ensu+ fla% caus$ a
 paddle-:eel to rotate4 ,m5tion is also 
made t x 0 an object to inject a little 
wat] into ! explod]1 9 ord] to /r5g!n ! 
=ce ( ! fla%4  ,rob]t ,/reet's pat5t (  
#agid m5tions a pi/on eng9e1 9 ! cyl9d] 
( :i*1 coal t>1 _s1 or turp5t9e 0       
vaporis$1 ! gases be+ ignit$ by a light 
burn+ outside ! cyl9d]4 ,! pi/on 9 ?is  
eng9e 0 ?r[n upw>ds1 ?is 9 turn =c+ a   
pump pi/on d[n :i* did "w 9 rais+ wat]4 
,?is 0 ! fir/ real gas eng9e1 ?\gh x 0  
crude & v imp]fectly arrang$4  ,9 #ahja 
,franzose ,lebon describ$ a ma*9e to be 
driv5 by means ( coal-gas4 ,two pumps 7 
us$ to compress air & gas1 & ! mixture 0
 fir$1 z recomm5d$ by ! inv5tor1 by an  
electric sp>k1 & drove a pi/on 9 a      
d\ble-work+ cyl9d]4  ,! atmosph]ic eng9e
 ( ,samuel ,br[n1 #ahbc1 _h a pi/on     
work+ 9 a cyl9d] into :i* gas 0         
introduc$1 & ! latt]1 be+ ignit$1 exp&$ 
! air 9 cyl9d] :il/ burn+ l a flame4 ,! 

fly-:eel c>ri$ ! pi/on up to ! top ( its
 /roke1 !n wat] 0 us$ to cool ! burnt   
gases1 :i* also escap$ ?r\gh valves1 !  
latt] clos+ :5 ! pi/on _h rea*$ ! top ( 
its /roke4 ,a p>tial vacuum 0 =m$1 & !  
atmosph]ic pressure did "w on ! pi/on on
 its d[n /roke4 ,a numb] ( cyl9d]s 7    
requir$ 9 ?is eng9e1 ?ree be+ %[n 9 !   
specification all connect$ to ! same    
crank-%aft4 ,accord+ to ! ,me*anic's    
,magaz9e1 su* an eng9e ) a complete gas 
g5]at+ plant 0 fitt$ to a boat :i* ran z
 an exp]im5t ^u ! ,?ames4  ,a two-cyl9d]
 eng9e work+ on to a beam 0 built 9     
,p>is1 b no useful results 7 obta9$4    
,wright's eng9e ( #ahcc us$ a mixture ( 
combu/ible gas & air1 :i* op]at$ l /eam 
9 a /eam eng9e4 ,?is eng9e _h a         
wat]-jacket1 c5trifugal gov]nor1 & flame
 ignition4 ,9 #ahch ,b>nett appli$ !    
pr9ciple ( compression to a s+le-act+   
eng9e4 ,he also employ$ a gas & air     
pump1 :i* 7 plac$ respectively on ei!r  
side ( ! eng9e cyl9d]1 communication be+
 e/abli%$ betwe5 ! receiv] into :i* !   

pumps deliv]$ & ! work+ cyl9d] z ! *>ge 
0 fir$4 ,! d\ble-act+ eng9es :i* ,b>nett
 devis$ lat] 7 n s successful4  ,f ?is  
"t to ab\t #ahfj v few practical        
developm5ts are record$4 ,a numb] (     
,fr5* & ,engli% pat5ts 7 tak5 out1      
ref]r+ to hydrog5 motors1 b are n ( mu* 
practical value4  ,l5oir's pat5t1 dat+ f
 #bd? ,janu>y #ahfj1 ref]s to a =m (    
eng9e :i* receiv$ consid]able comm]cial 
support1 & consequ5tly became v popul>4 
,a manufactur]1 nam$ ,m>9oni1 built     
sev]al ( ^! eng9es1 :i* 7 set to "w 9   
,p>is 9 a %ort "t4 ,!n1 due to sudd5    
dem&1 ! ,l5oir ,company 0 =m$ to        
und]take ! manufacture ( ^! eng9es4 ,x 0
 claim$ t a #d-;horse-p[] eng9e c\ld be 
run at a co/ ( #c4d %ill+s p] day1 or j 
"o half ! co/ ( a /eam eng9e us+ #i4i   
p\nds ( coal p] horse-p[] p] h\r4 ,_m   
simil> exagg]at$ acc\nts ( _! economy 9 
consumption 7 circulat$1 & ! public1 on 
! /r5g? ( ^! figures1 b\ght4  ,x 0      
und]/ood t #ag4f cubic ft4 ( gas 7      
requir$ p] horse-p[] p] h\r1 b x 0 f\nd 

t z mu* z #aje cubic ft4 7 (t5 consum$4 
,! discrepancy betwe5 ! /at$ figures & !
 actual p]=mance ( ! eng9e 0 a          
disappo9tm5t to ! us+ public1 &1 z a    
result1 ! ,l5oir eng9e got a bad "n4    
,hugon1 director ( ! ,p>isian gas-works1
 :o1 toge!r ) ,rei?mann1 a wat*mak] (   
,mu5i*1 hotly conte/$ ,l5oir's priority 
to ?is inv5tion1 br\ght out a           
modification ( ?is eng9e4 ,he cool$ !   
cyl9d] by inject+ wat] z well z us+ a   
wat]-jacket1 & us$ flame in/ead (       
electric ignition4 ,! consumption 0 n[  
br\ght d[n to #hg4e cubic ft4  ,at !    
second ,p>isian ,int]national           
,exhibition1 #ahfg1 an atmosph]ic eng9e1
 inv5t$ by ,otto  ,lang5 ab\t ?is "t1 0 
%[n4 ,9 ?is eng9e a free pi/on 0 us$ 9 a
 v]tical cyl9d]1 ! =m] be+ ?r[n up by ! 
=ce ( ! explosion4 ,! only "w done on ! 
up-/roke 0 t to ov]come ! weight ( !    
pi/on & pi/on rod1 & ! latt] be+ made 9 
! =m ( a rack1 engag$ ) a too!d :eel on 
! axle z ! pi/on desc5d$1 caus+ !       
fly-:eel & pulley to rotate4  ,b>santi &

 ,matteucci 7 engag$ 9 devis+ &         
exp]im5t+ ) an eng9e v simil> to ?is "s 
ye>s be=e1 b ,otto  ,lang51 no d\bt1    
work$ q indep5d5tly4 ,b>santi's eng9e   
nev] became a comm]cial article2 :ile   
,otto  ,lang5's firm1 x is said1 held _!
 own = t5 ye>s1 & turn$ out ab\t #djjj  
eng9es4 ,9 #ahfb ! ,fr5* eng9e]1 ,beau  
de ,ro*as1 laid d[n ! necess>y          
conditions :i* mu/ prevail 9 ord] to    
obta9 maximum effici5cy4 ,8 pat5t says  
!re are f\r conditions = p]fectly       
utilis+ ! =ce ( expansion ( gas 9 an    
eng9e4  7#a7 ,l>ge/ possible cyl9d]     
volume conta9$ by a m9imum ( surface4   
7#b7 ,! highe/ possible spe$ ( work+4   
7#c7 ,maximum expansion4  7#d7 ,maximum 
pressure at beg9n+ ( expansion4  ,^! are
 ! conditions & pr9ciples1 briefly /at$1
 t comb9e to =m ! n[ well-kn[n cycle ^u 
:i* mo/ gas eng9es "w at ! pres5t "t4   
,x 0 n until #ahgf1 fifte5 ye>s aft] ^! 
pr9ciples _h be5 enum]at$1 t ,otto c>ri$
 !m into practical effect :5 he br\ght  
out a new type ( eng9e1 ) compression   

be=e ignition1 high] pi/on spe$1 m rapid
 expansion1 & a g5]al r$uction (        
dim5sions = a giv5 p[]4 ,due to ?is     
a*ievem5t1 ! cycle above ref]r$ to has  
always be5 t]m$ ! ,otto cycle4          
,,*apt] ,,ii  ,,! ,,compon5t ,,p>ts ,,( 
,,an ,,eng9e   ,hav+ rec\nt$ v briefly !
 *ief po9ts 9 ! developm5t ( ! gas eng9e
 f its beg9n+1 we may proce$ to deal )  
matt]s ( p]haps m practical int]e/ to ^?
 :o we are assum+ h _h little or no     
actual exp]i5ce 9 mak+ or work+ int]nal 
combu/ion eng9es4  ,! mod]n gas eng9e   
comprises comp>atively few p>ts4 ,ap>t f
 ! two ma9 ca/+s--! b$ & cyl9d]--a small
 eng9e1 g5]ally speak+1 consi/s ( f\r   
fundam5tal memb]s1 viz41 ! valves & _!  
op]at+ me*anism1 ! cams & lev]s2 !      
ignition device = fir+ ! *>ge2 & !      
gov]n+ me*anism = regulat+ ! supply &   
admission ( ! explosive *>ge4 ,!re are  
innum]able designs ( ea* "o ( ^! p>ts1 &
 no two makes are precisely alike 9     
detail1 z e mak] employs 8 own me?od (  
a*iev+ ! same end1 namely1 ! production 

( an eng9e :i* comprises maximum        
effici5cy ) a m9imum ( we> & te> &      
att5tion4  ,!re=e1 be=e deal+ ) ea* ( ^!
 prim>y p>ts 9 an arbitr>y mann]1 & ) ! 
cycle ( op]ations 9 detail1 we propose  
to make ! read] famili> ) ! g5]al       
arrangem5t & me?od ( work+ :i* usually  
obta9s 9 ! small] p[] eng9es4 ,9 !      
foll[+ illu/rations ^! p>ts are %[n4 ,a 
7fig4 #a7 is ! ignition device :i*      
c>ries ! ignition tube to fire ! *>ge4  
,h & ,i 7fig4 #b7 are ! ma9 valves1 &   
,,gc 7fig4 #a47 is ! gas-cock4 ,! side  
or cam %aft ,n 7sometimes call$ ! #b to 
#a %aft71 ! cams :i* move ! lev]s ,m1 ! 
latt] 9 turn op]at+ ! valves1 & caus+ !m
 to op5 & close at ! prop] "t1 are %[n 9
 fig4 #aa4 ,a bracket bolt$ up to ! side
 ( cyl9d] =ms a be>+ = "o end ( ! side  
%aft1 & also c>ries a sp9dle at its l[] 
end on :i* ! lev]s oscillate1 transmitt+
 ! motion imp>t$ to !m by ! cams to !   
valves4 ,! ma9 cyl9d] ca/+ & ! b$ ne$ no
 description4 ,9 "s cases ! b$ is 9 two 
portions1 ?\gh n[ a great _m mak]s are  

disc>d+ ! l[] portion altoge!r1 hav+    
f\nd t x is *eap]1 & q z satisfactory1  
to use a built-up f\ndation in/ead1 &1  
if necess>y1 to cut a tr\gh = ! fly-:eel
 to run x4 ,?is arrangem5t1 h[ev]1 only 
obta9s :]e l>g] eng9es are conc]n$4 ,a  
half-compression h&le by :i* ! exhau/   
cam is mov$ lat]ally on ! side %aft z   
requir$ is n ne$$ on v small eng9es4    
,illu/ration3 ,,fig4 #a4--;,g5]al       
,arrangem5t ( a ,gas ,eng9e &           
,accessories4  ,fur!r ref]5ce w be made 
to ?is 9 ano!r *apt]1 &1 al?\gh ?is is n
 a necessity on a small eng9e1 x is     
always employ$ on eng9es ov] #b         
,b4,h4,p4 ,9 fig4 #a1 ,,hw is ! cool+   
wat] outlet & ,,cw ! inlet4 ,a small    
dra9 cock is %[n at ,,dc1 ?r\gh :i* !   
wat] 9 ! cyl9d] wat]-jacket may be drawn
 (f :5 requir$4 ,! pipes lead+ to !     
inlet & outlet ( ?is supply are connect$
 to ! cool+ wat] tank by means ( a c\ple
 ( broad1 flat nuts & lead wa%]s1 "o    
inside & ! o!r outside ! tank1 ! latt]1 
:5 clamp$ up well1 mak+ a p]fectly      

wat]-tight jo9t4 ,! outlet pipe mak+ an 
acute angle ) ! side ( tank1 ! wa%]s us$
 !re %\ld be w$ge-%ape 9 section4 ,x is 
also desirable to fit a /op-cock ,,sc1 s
 t ! pipes c be disconnect$ f ! eng9e   
entirely1 or ! wat]-jacket empti$ )\t   
runn+ ! :ole ( ! wat] out ( ! tank4 ,!  
exhau/ pipe ,,ep is made up ( gas-b>rel4
 ,x %\ld lead f ! eng9e to ! sil5c] or  
exhau/ box 7if "o is f\nd to be         
necess>y7 z directly z possible1 i4e41 )
 no m b5ds ?an are ne$$1 & :at !re are  
%\ld n be acute4 ,! sil5c] c be inside  
or outside ! eng9e-room1 :i*ev] is mo/  
conv5i5t2 b bo? x & ! exhau/ pip+ %\ld  
be kept f all direct contact ) wood-"w1 
& at ! same "t 9 a readily accessible   
position4  ,beyond ! exhau/-pipe & box &
 ! wat]-tank1 ! gas bag ,,gb & gas met] 
7:]e small p[]s are conc]n$1 ! ord9>y   
h\se or work%op light+ met] may be us$  
)\t inconv5i5ce7 are ! only o!r         
accessories :i* are includ$ 9 a small   
in/allation4  ,illu/ration3 ,,fig4      
#b4--;,a ,section ( a ,gas ,eng9e4      

,fig4 #b gives a sectional view1 %[+ !  
cyl9d] & l9]4 ,! latt] is a v desirable 
feature 9 any type ( gas eng9e1 b       
especially 9 ! l>g] sizes2 = at any     
future "t1 %\ld x be f\nd necess>y to   
re-bore ! l9]1 x c be remov$ )          
comp>ative ease1 & is1 moreov]1 m       
readily dealt ) 9 ! la! ?an ! :ole      
cyl9d] ca/+ w\ld be4  ,! l9] is         
virtually a ca/-iron tube1 ) a specially
 %ap$ flange at ei!r end4 ,at ! back end
 ! jo9t betwe5 x & ! cyl9d] ca/+ has to 
be v c>efully made4 ,?is is a wat] &    
explosion jo9t2 h5ce x has n only to    
prev5t wat] ent]+ ! cyl9d] f !          
wat]-jacket1 b also to be suffici5tly   
/rong to )/& ! pressure g5]at$ 9 !      
cyl9d] :5 ! *>ge is fir$4 ,= ?is purpose
 specially prep>$ copp]$ asbe/os r+s are
 us$1 :i* w /& bo? wat] & int5se heat4  
,sometimes a copp] r+ alone is employ$  
to make ! jo9t4 ,at ! front end ! l9] is
 j a good fit1 & ent]s ! b$ easily1 & a 
c\ple ( bolts fitt$ 9 correspond+ lugs  
on ! l9]1 pass ?r\gh ! back end ( cyl9d]

 ca/+1 s t by tight5+ up ^! ! jo9t at   
back end is made secure4 ,a small groove
 is cut on a flange1 & a rubb] r+1 (    
ab\t #a_/d-;94 sectional diamet]1 is    
ins]t$ "h :5 ! l9] is fitt$ into !      
cyl9d] ca/+4 ,?is makes ! wat]-jacket   
jo9t at ! front end4  ,illu/ration3     
,,fig4 #c4  ,illu/ration3 ,,fig4 #e4    
,illu/ration3 ,,fig4 #d4  ,lugs are     
provid$ on ! b$ & cyl9d] ca/+s1 & are   
bor$ to receive /eel bolts--?ree are    
suffici5t1 provid$ ! metal 9 & ar\nd ^! 
lugs is n p9*$4 ,9 "s cases a cont9u\s  
flange is provid$ on bo? b$ & cyl9d]1 & 
a numb] ( bolts ins]t$ all ! way r\nd4  
,?is1 h[ev]1 is unnecess>y1 & has a     
some:at clumsy appe>ance4 ,:5 ^! bolts  
are tight5$ up1 ! cyl9d] & l9] are      
clamp$ firmly to ! b$2 b ! l9] be+ free 
at ! op5 end1 c exp& longitud9ally )\t  
caus+ /resses 9 ! cyl9d] ca/+4  ,!      
combu/ion *amb] ,k is virtually "p ( !  
cyl9d]1 & has approximately equal to    
"o-f\r? ! total volume ( ! cyl9d]4 ,!   
%ape v>ies some:at 9 diff]5t makes (    

eng9es2 9 "s x is rectangul>1 ) all !   
corn]s well r\nd$ (f2 9 o!rs x is       
practically a cont9uation ( ! cyl9d]1   
i4e41 x is circul> 9 cross-section1 ) ! 
back end m or less sph]ical2 :ile1 aga91
 x is made slightly oval 9              
cross-section2 b 9 e case ! corn]s %\ld 
be well curv$ & r\nd$ (f1 s t !re is no 
"o "p :i* is liable to become heat$     
disproportionately ) ! re/ ( ! ca/+2 9  
fact1 9 ! :ole cyl9d] ca/+ !re %\ld be  
no sudd5 *ange1 b a uni=mity 9 !        
?ickness ( ! metal employ$4 ,?is po9t   
%\ld be c>efully rememb]$1 al?\gh x     
applies m p>ticul>ly to ^? p>ts ( ! ca/+
 subject$ to high] temp]atures ?an !    
re/4  ,! ma9 be>+s are usually ( brass  
or gun-metal1 & are adju/$ = runn+ 9 !  
same mann] z any /eam or o!r eng9es w\ld
 be4 ,! brasses are 9 halves1 & are held
 d[n by ! ca/-iron caps1 z %[n 9 fig4   
#a4  ,^! be>+s require extremely little 
att5tion1 & d n %[ ! we> & te> ( runn+  
ne>ly s soon z ! connect+-rod brasses4  
,^!1 too1 are usually ( brass or        

gun-metal2 b !re are v>i\s =ms (        
con/ruction employ$ 9 connection ) !    
back end or pi/on p9 be>+s4 ,on v small 
eng9es ! connect+ rod is swoll5 at !    
back end 9 ! =g+1 & !n ma*9$ up &       
drill$1 z %[n 9 fig4 #c4 ,9 ?is hole !  
brasses are ins]t$ aft] be+ scrap$ up to
 a good fit on ! pi/on p94  ,a flat is  
cut on "o ( ! brasses1 & a set screw is 
fitt$1 z %[n1 to prev5t any movem5t ( ! 
latt] aft] ! f9al adju/m5t has be5 made4
 ,a lock nut %\ld be us$ 9 conjunction )
 ?is set screw4 ,ano!r me?od1 & "o m    
g5]ally us$ on l>g] eng9es1 is %[n 9    
fig4 #d4 ,9 ?is case ! brasses are l>g] 
?an 9 ! =m]1 :]e !y are virtually a     
split bu%2 "h !y h holes drill$ 9 !m to 
take ! bolts1 ! latt] usually &         
pref]ably be+ turn$ up to ! %ape %[n 9  
fig4 #e4     ,,*apt] ,,iii  ,,h[ ,a     
,,gas ,,eng9e ,,works   ,! gas eng9e ( !
 pres5t day1 al?\gh f a /ructural po9t (
 view is v diff]5t to ! e>ly eng9e1 or  
ev5 t ( fifte5 ye>s ago1 is1 9 respect  
to ! pr9ciple ^u :i* x works1 v simil>4 

,! great] numb] ( small] p[] eng9es 9   
use 9 ?is c\ntry "w on :at is kn[n z !  
,otto or f\r-cycle pr9ciple2 & x is )   
?is class ( eng9e we propose to deal4   
,ref]5ce to ! v>i\s diagrams 9 ! text w 
help consid]ably1 & make x an easy matt]
 = any read] hi!rto totally unacqua9t$ )
 su* eng9es to see :y & h[ !y "w4       
,coal-gas consi/s prim>ily ( five o!r   
gases1 mix$ toge!r 9 c]ta9 proportions1 
^! proportions v>y+ slightly 9 diff]5t  
p>ts ( ! c\ntry3--,hydrog5 7,h71 #ej2   
m>% gas 7,,*#d71 #ch2 c>bon-monoxide1   
#d2 olef9es 7,c#f;,h#d71 #d2 nitrog5    
7,n71 #d4  ,gas alone is n explosive2 & 
be=e any practical use c be made ( x1 a 
consid]able quantity ( air has to be    
add$1 dilut+ x d[n to approximately t5  
p>ts air to "o ( pure gas4 ,?is mixture 
is n[ highly explosive4  ,! read] w d   
well to be> ^! facts con/antly 9 m9d1   
especially :5 he is repair+1 adju/+1 or 
exp]im5t+ ) a gas eng9e4 ,we wi% to     
emphasise ?is at ! outset1 because a    
consid]ation ( ^! facts w keep cropp+ up

 ?r\gh\t all our deal+s ) ! gas eng9e1 &
 if once a fairly cle> conception is    
obta9$ ( h[ gas w behave "u c]ta9 &     
v>i\s conditions1 half1 or ev5 m ?an    
half1 our tr\bles w disappe>2 ! cry t ! 
gas eng9e has gone wrong w be he>d less 
(t51 & us]s w\ld soon le>n t ! gas eng9e
 is 9 reality z wor?y ( _! confid5ce z  
any o!r =m ( p[] g5]ator 9 common use4  
,b to rev]t to ! explanation ( ! cycle (
 op]ations4 ,! cycle is complet$ 9 f\r  
/rokes ( ! pi/on1 i4e41 two revolutions 
( ! crank %aft4  ,at ! comm5cem5t ( !   
fir/ out-/roke 7! *>g+ or suction /roke7
 gas & air are admitt$ to ! cyl9d] ?r\gh
 ! respective valves 7fig4 #f71 &       
cont9ue to be drawn 9 by :at may be t]m$
 ! suck+ action ( ! pi/on1 until !      
completion ( ?is /roke 7! precise       
position ( ! clos+ & op5+ ( ! valves w  
be ref]r$ to lat] on74 ,! next /roke    
7fig4 #g7 is ! compression /roke4 ,all !
 valves are clos$ :il/ ! pi/on moves    
inw>ds1 compress+ ! gases1 until at !   
end ( ?is /roke1 & at ! in/ant ( maximum

 compression1 ! highly explosive *>ge is
 fir$ by means ( ! hot tube or an       
electric sp>k1 z ! case may be4 ,! ensu+
 /roke--! second out-/roke ( ! cycle--is
 ! result ( ! explosion1 ! exp&+ gases  
driv+ ! pi/on rapidly be=e !m2 ?is1 !n1 
is ! expansion1 or work+ /roke 7fig4    
#h47  ,illu/ration3 ,,fig4              
#f4--;,comm5cem5t ( fir/ out-/roke      
suction or *>g+ /roke4 ,gas & air valve 
ab\t to op54  ,illu/ration3 ,,fig4      
#g4--;,compression /roke1 dur+ :i* all  
valves rema9 clos$4  ,dur+ ! la/--!     
second inw>d--/roke 7fig4 #i7 ! exhau/  
valve is op5$1 & ! return+ pi/on sweeps 
all ! burnt gases 7! product (          
combu/ion7 out into ! exhau/ pipe & s   
into ! atmosph]e4 ,?is completes !      
cycle1 & ! pi/on1 crank1 & valves are 9 
! same relative positions z =m]ly1 & !  
same s]ies ( op]ations is repeat$ aga9 &
 aga94 ,( c\rse1 x is n always ! case t 
bo? air & gas valve are op5$ on ! *>g+  
/roke2 t dep5ds ^u ! me?od employ$ to   
gov]n ! spe$ ( ! eng9e4 ,suppos+ x 7    

gov]n$ on ! hit & miss pr9ciple 7to be  
expla9$ h]eaft]71 ! gas valve w\ld be   
all[$ to rema9 clos$ dur+ ! *>g+ /roke1 
& air alone w\ld be drawn into ! cyl9d]1
 !n compress$1 b n be+ explosive w\ld   
simply exp& aga9 on ! work+ /roke1 giv+ 
back ne>ly all ! en]gy :i* 0 absorb$ 9  
compress+ x1 & f9ally be exhau/$ 9 !    
same mann] z ! burnt gases are4         
,illu/ration3 ,,fig4 #h4--,second out   
/roke1 %[+ position ( valves dur+ work+ 
/roke4  ,illu/ration3 ,,fig4            
#i4--,second inw>d /roke1 %[+ position (
 valves dur+ ! exhau/ /roke4            
,illu/ration3 ,,fig4 #aj4--;,fir/       
out-/roke1 %[+ position ( valves dur+ ! 
*>g+ /roke4  ,fig4 #aj %[s              
diagrammatically ! position ( crank1    
pi/on1 & valves dur+ ! *>g+ /roke4      
,illu/ration3 ,,fig4 #aa4--;,cross      
,section ( ,cyl9d]4  ,9 figs4 #a & #b we
 gave draw+s ( two gas eng9es1 :i* are  
typical examples ( mod]n practice4 ,huge
 /rides h be5 made 9 rec5t ye>s 9       
gas-eng9e "w1 z reg>ds bo? workman%ip & 

effici5cy1 s t to-day we h 9 ! gas eng9e
 a ma*9e ^: me*anical effici5cy comp>es 
fav\rably ) t ( any o!r p[] g5]ator1 &  
^: !rmal effici5cy is v mu* great]4     
,illu/ration3 ,,fig4 #ab4--,longitud9al 
,section ( ,cyl9d]4  ,figs4 #aa & #ab %[
 respectively a sectional end & side    
elevation ( ! cyl9d]1 f :i* x w n be    
difficult = ! read]1 h[ev] unacqua9t$ he
 may be ) gas-eng9e "w1 to see h[ !     
v>i\s requirem5ts & peculi>ities ( !    
eng9e %\ld be consid]$ & provid$ =4  ,a 
mo/ important desid]atum 9 any ma*9e or 
eng9e is t x %all be z simple 9         
con/ruction z ev] possible2 complicat$  
me*anism %\ld only be introduc$ :5 su*  
addition or complication comp5sates     
adequately = :at mu/ necess>ily be a    
high] fir/ co/1 & incid5tally ! great]  
we> & te> & att5tion involv$4 ,figs4 #aa
 & #ab %[ :at has be5 done to simplify !
 con/ruction ( ! gas eng9e 9 rec5t ye>s4
 ,! ma9 feature 9 ?is case is ! v       
get-at-able position ( ! two ma9        
valves--! air valve ,f & ! exhau/ ,e4   

,^! valves1 z may be se5 f ! draw+1 are 
capable ( )drawal aft] ! cov] ( !       
combu/ion *amb] has be5 remov$4 ,! latt]
 is an iron ca/+1 %ap$ & fac$ up to make
 an absolutely tight jo9t2 no asbe/os or
 any pack+ is us$ to make ?is jo9t--& is
 held 9 place by f\r /uds1 z %[n4 ,?us1 
all t is necess>y is to remove ! f\r    
nuts1 lift ! cov] (f1 !n pull out ! p9s 
:i* keep ! spiral spr+s 9 position1 &   
)draw ! valves4 ,! latt] are seat$      
direct on to ! metal ( ! cyl9d] ca/+1 ! 
gun-metal bu%es ,a & ,b act+ z guides4  
,fur!r ref]5ce to ,a 7! mix]71 :i* s]ves
 a tw(old purpose1 w be made lat] on4   
,! gas valve & cock are m\nt$ 9 a       
sep>ate ca/+1 :i* is c>ri$ by a c\ple ( 
/uds1 ! jo9t betwe5 ?is & cyl9d] be+    
made ) a piece ( rubb] ins]tion4 ,! gas 
ent]s at ! gas-cock1 passes ?r\gh !     
valve & port ,g1 & r\nd ! annul> space 9
 ! bu% or mix] ,a1 previ\sly m5tion$1 & 
!nce ?r\gh a numb] ( small holes 9 same1
 imm$iately bel[ ! seat ( ! air valve   
,f4 ,at ! same "t1 pure air is drawn 9  

via ! air box 7z expla9$ h]eaft]71 ?r\gh
 port ,l 7fig4 #aa71 & !nce up ! c5tre (
 bu% ,a & ov] ! small holes ?r\gh :i* ! 
gas is fl[+4 ,! two !n ?or\ghly mix &   
ent] ! combu/ion *amb] toge!r z ! air   
valve ,f is op5$4 ,?is device produces a
 p]fectly homog5e\s mixture1 :i*        
conduces 9 no small measure to p]fect   
combu/ion :5 ! explosion takes place1 & 
^u :i*1 to a v great ext5t1 dep5ds !    
effici5cy ( ! eng9e4 ,besides possible  
loss 9 ?is direction1 h[ev]1 !re is     
ano!r s\rce ( wa/e :i* _c be elim9at$1 &
 t is ! heat tak5 away by ! cool+ wat]  
:i* surr\nds ! cyl9d]4 ,z ?is loss is   
inevitable1 ! be/ ?+ we c d is to make x
 z small z possible4 ,!oretically1 x    
w\ld be no small advantage if we c\ld "w
 at v mu* high] temp]atures ?an we d at 
! pres5t "t1 & x is only c]ta9 me*anical
 difficulties :i* b> ! way & s          
effectually prev5t ! already high !rmal 
effici5cy ( ! eng9e be+ greatly         
increas$4  ,x is no easy matt] to       
ov]come ^! difficulties completely1 b   

improvem5ts 9 ?is direction are         
cont9ually be+ made1 s t tr\bles :i*    
att5d$ ! gas-eng9e us] ye>s ago no long]
 exi/4  ,all t we require ( ! cool+ wat]
 is t x %all keep c]ta9 work+ p>ts ( !  
eng9e at a reasonable temp]ature2 =     
in/ance1 ! cyl9d] mu/ n be s hot z to   
deprive ! lubricat+ oil ( its prop]ty to
 lubricate1 nei!r mu/ ! exhau/ valve    
become s hot z to cause x to seize 9 !  
bu% & /ick up2 b1 beyond su*            
consid]ations z ^!1 ! high] ! temp]ature
 is at ! comm5cem5t ( ea* explosion ! m 
effici5t w ! eng9e be4 ,! object1 !n1 is
 to d z little cool+ z possible1 & to   
apply ! cool+ effect at ! "r p>ts2 h5ce 
! passages & *amb]s ?r\gh :i* ! cool+   
wat] circulates %\ld be s arrang$ t ^?  
:i* require to be kept at a l[          
temp]ature are 9 close proximity to !   
cool+ wat]4 ,on "s ( ! eng9es ( days    
gone by1 ! exhau/ valve 0 c>ri$ 9 a l>ge
 iron ca/+1 ?is 9 turn be+ bolt$ to !   
cyl9d] ca/+ & communicat+ ) ! combu/ion 
*amb] by means ( a port4 ,su* an        

arrangem5t 0 f\nd to be n only clumsy b 
ineffici5t2 ! wat] passages 7 small &   
difficult to get at2 !y readily furr$   
up2 & moreov]1 ! jo9t betwe5 ?is ca/+ & 
! cyl9d] 0 necess>ily a wat] & explosion
 jo9t1 & ! few] we h ( ^! ! bett]4  ,!  
me?od--if x may be call$ a me?od--(     
ov]com+ or prev5t+ ! exhau/ valve becom+
 too hot is1 9 ! case ( figs4 #aa & #ab1
 simply "o ( judici\s arrangem5t &      
design4 ,! cool+ wat] ent]s by ! inlet  
,k 7fig4 #aa71 & circulates r\nd !      
exhau/ valve port ,x & valve ,e         
imm$iately1 be=e becom+ heat$1 ?us keep+
 ! hotte/ ( ! work+ p>ts ( ! eng9e at a 
suitable temp]ature2 & ! valve seat1 be+
 9 direct metallic communication ) !    
cold wat]1 does n become burnt or pitt$4
 ,on ! o!r side ( ! exhau/ valve we h ! 
air valve & its passages1 ?r\gh :i* cool
 air is cont9ually be+ drawn2 ?is also  
helps to keep ! exhau/ valve cool4  ,f  
?is1 !n1 we may conclude t ov]heat+ ( ! 
cyl9d] w n occur "u normal conditions1  
giv5 an eng9e ( good design2 b1 if ?is  

tr\ble does arise1 we may safely look   
fir/ ( all = "s defect 9 ! cool+ wat]   
circulation4 ,"s wat]s conta9 a great]  
am\nt ( impurities ?an o!rs1 &          
consequ5tly ! wat] space may furr up m  
rapidly 9 "o di/rict ?an 9 ano!r4 ,b ?is
 deposit1 ev5 "u ! wor/ conditions1     
accumulates v sl[ly1 & ! op]ation (     
clean+ out ! wat]-jacket is a v         
infrequ5t necessity4 ,! exhau/ valve1   
h[ev]1 may become ov]heat$ if x is all[$
 to get into bad condition1 i4e41 leaky4
 ,its seat %\ld be well look$ aft]1 or !
 hot gases w bl[ pa/ :5 x is presumably 
%ut2 & if ?is defect1 slight ?\gh x may 
be to beg9 )1 is all[$ to develop1 bo? !
 seat1 ! valve head1 & ! sp9dle w become
 burnt away & pitt$1 p]haps badly1 due  
to ! excessive heat4     ,,*apt] ,,iv   
,,ignition ,,devices   ,! ignition      
devices commonly employ$ may be divid$  
into ?ree ma9 classes--! metal tube1 !  
porcela9 tube1 & ! electric ignition4   
,^! aga9 may be subdivid$3 ,! fir/ be+  
ei!r iron or nickel 7hecknum z !y are   

sometimes call$72 ! second are ( two    
k9ds--s+le-end$ & d\ble-end$2 & ! ?ird  
takes _m =ms :i* _m ( my read]s are     
possibly well acqua9t$ )1 su* z !       
magneto1 ! induction coil & trembl]1 & !
 high-t5sion magneto ignition1 ! latt]  
device hav+ be5 us$ successfully on     
v>i\s occasions1 ?\gh n yet univ]sally  
adopt$4  ,! fir/-nam$ h "o or two       
advantages ov] ! nickel tube4 ,!y are v 
inexp5sive1 & are easily heat$ to !     
requir$ temp]ature2 moreov]1 !y c be    
made at home1 %\ld occasion dem&4 ,on ! 
o!r h&1 !y are n s durable1 h a v       
unc]ta9 life1 & consequ5tly ne$ r5ew+   
frequ5tly--_! av]age life be+ n m ?an   
#fj work+ h\rs4 ,fig4 #ac gives an      
outl9e draw+ ( an iron tube1 ) its burn]
 & *imney fix$ 9 position4 ,! tube is v 
simil> to a piece ( #a_/d-;94 gas-b>rel1
 clos$ up at "o end & a tap] ?read      
7#a_/d-;94 gas7 cut on ! o!r2 9 fact1   
gas-b>rel may be us$ = mak+ ^! tubes at 
home--& measure ab\t #g or #h 94 ov] all
 ,x is screw$ into a fir+ block1 :i* 9  

turn is screw$ into ! combu/ion *amb]   
end1 s t :5 "r home x is 9 su* position 
t ! tube /&s q v]tical4 ,! section ( !  
tube1 fig4 #ac1 %[s ! condition x gets  
into aft] hav+ be5 9 use "s "t4 ,! bore1
 x w be se51 has become almo/ completely
 clos$ up1 s t !re is practically no    
communication betwe5 ! hot "p ( ! tube &
 ! combu/ion *amb]4 ,?is clos+ up ( !   
bore is v gradual1 & x is 9 ! e>ly /ages
 ( ?is process t erratic fir+ is likely 
to occur2 sometimes ! *>ge w be         
successfully fir$ & sometimes n4 ,x may 
be z well to m5tion "h t ! l5g? ( !     
tube1 al?\gh to a c]ta9 ext5t immat]ial1
 %\ld nei!r be excessively long nor     
abnormally %ort1 ! precise l5g? v>y+ ) !
 size ( ! eng9e4 ,a #a_/d-;94 tube1 #h  
ins4 long1 may be us$ successfully on   
eng9es rang+ f #a_/b to #f horse-p[]1   
provid$ a suitable burn] is fitt$ enabl+
 ! tube to be heat$ at any requir$ spot4
 ,aft] ! fir/ *>ge has be5 fir$1 & !    
exhau/ takes place1 practically all !   
burnt gases are cle>$ out ( ! cyl9d]1 b 

a small am\nt ( ^! w g5]ally rema9 9 !  
tube & ! bore ( ! fir+ block4 ,on !     
ensu+ compression /roke ^! in]t gases   
are compress$ to ! f> end ( ! tube1 ?us 
mak+ way = ! explosive mixture to rea* !
 hot portion1 & explode1 ?us s5d+ a jet 
( flame into ! ma9 volume ( ! mixture   
:i* is imm$iately ignit$4 ,h5ce !re is  
no advantage 9 hav+ a tube too long1    
:ile1 on ! o!r h&1 x mu/ n be too %ort4 
,illu/ration3 ,,fig4 #ac4  ,illu/ration3
 ,,fig4 #ad4  ,illu/ration3 ,,fig4 #ae4 
,! asbe/os l9+1 %[n 9 fig4 #ac1 may be (
 v>i\s ?icknesses1 accord+ to ! size ( !
 *imney & ! tube2 ! reason = ?is w be   
app>5t to _m2 b be+ a mo/ important     
factor 9 ! heat+ ( ! tube1 & consequ5tly
 ! work+ ( ! eng9e1 x w be advisable to 
deal ) ?is po9t m fully4  ,due ma9ly to 
! peculi> behavi\r ( iron tubes "u heat 
& int]nal pressure1 x is always         
advisable to look to !m fir/ ( all :5 ! 
eng9e %[s signs ( miss+ fire2 & to      
always exam9e ! bore ( a fre% "o1 &     
asc]ta9 t x is p]fectly cle> be=e putt+ 

x 94 ,! adju/m5t ( ! ignition tube1     
al?\gh "o ( ! mo/ important & necess>y  
to be made on ! :ole eng9e1 is 9 itself 
a p]fectly simple matt]4 ,x mu/ be      
und]/ood t ! ignition tube _c1 ) !      
ord9>y means at our disposal1 be kept at
 too high a temp]ature2 b x mu/ n be    
assum$ t ei!r ! size ( ! flame1 or ! "t 
! flame has be5 alight1 is conclusive   
evid5ce t ! tube is1 or ought to be1    
suffici5tly hot to fire ! *>ge          
successfully4 ,x is an uncommon ?+ to   
he> a man exclaim--aft] x has be5 po9t$ 
out t 8 tube is practically cold--,:y1  
x's be5 alight = h\rs6  ,if su* is !    
case ) y1 read]1 y may v rightly assume 
t ! burn] is n prop]ly adju/$1 & s does 
n give ! "r k9d ( flame4  ,9 ord] to get
 ! hotte/ possible flame1 ! quantity (  
gas & air mu/ be mix$ 9 ! "r            
proportions4 ,a common fault is t !re is
 too mu* gas all[$ to fl[ ?r\gh !       
nipple1 comp>$ ) ! am\nt ( air be+ drawn
 9 at ! air ap]ture1 fig4 #ac4 ,! result
 is1 we get a flame ( great l5g?1 b "o  

:i* is n at all suit$ to our            
requirem5ts2 & in/ead ( giv+ up its heat
 to ! tube & ! asbe/os l9+ ( ! *imney1 a
 l>ge am\nt ( gas we are presumably     
burn+ 9 ! *imney is n be+ burnt !re at  
all1 =1 on apply+ a light j above !     
*imney top1 a quantity ( ?is gas we are 
wa/+ w be se5 to burn ) a flick]+ blue  
flame4  ,to put matt]s "r1 x is necess>y
 to d "o ( two ?+s--ei!r cut d[n !      
supply ( gas or increase ! air-supply4  
,provid+ ! air ap]ture is normal1 i4e41 
! same size z x 0 orig9ally1 x is bett] 
to adju/ ! gas1 :i* may be done by tapp+
 up ! nipple ,n1 z indicat$ 9 ! enl>g$  
sket*1 fig4 #ad1 until j ! "r am\nt (   
gas c fl[4  ,z a rule1 if !re is too mu*
 air1 ! flame w burn ) a l\d ro>+ noise1
 & is liable to fire back4 ,! nipple    
%\ld !n be op5$ out ) a small ream]--!  
tang ( a small file1 gr\nd to a long    
tap] po9t1 makes an admirable tool = ?is
 purpose4 ,:e!r ! burn] is ( ! ord9>y   
buns5 type1 or ! r+ or /ove type1 !     
above rem>ks apply1 z 9 e case ! fl[ (  

gas is gov]n$ by ! size ( ! orifice     
?r\gh :i* x fl[s4  ,!re is no ne$ to use
 any?+ beyond a t\* ( oil :5 putt+ 9 a  
new tube1 9 ord] to make a p]fectly     
tight jo9t2 :ite or r$ lead are q       
unnecess>y1 & are liable to make x a    
tr\blesome matt] to remove ! tube on    
future occasions4 ,nei!r %\ld undue =ce 
be appli$ :5 putt+ 9 new tubes2 x is    
liable to we> ! ?read 9 ! fir+ block1   
:i* results 9 a p>tial /oppage ( !      
ignition hole1 z indicat$ 9 fig4 #ae4   
,?is is especially ! case if we happ5 to
 get hold ( a tube ) its screw$ "p      
slightly small] ?an usual4  ,! asbe/os )
 :i* ! *imney is l9$ %\ld be ab\t #a_/h 
94 ?ick1 &1 :5 r5ew+1 ! same ?ickness   
%\ld be us$ z orig9ally4 ,a ?ick] bo>d w
 r$uce ! annul> space r\nd ! tube1 & w h
 a *ok+ effect on ! flame--mu* ! same z 
ref]r$ to above1 :5 !re is too mu* gas &
 n en\gh air4 ,a simple me?od ( l9+ !   
*imney is to cut a block ( wood to !    
inside dim5sions ( ! *imney1 less #a_/d 
94 9 wid? & ?ickness1 !n s(t5 ! asbe/os 

c>dbo>d by imm]s+ 9 wat]1 & b5d x r\nd !
 wood1 cutt+ (f to ! requir$ size1 i4e41
 till ! two edges =m a neat butt jo9t4  
,x c be all[$ to rema9 on ! m\ld until  
dry--:5 x w reta9 its %ape--or c be put 
into ! *imney /raight away1 if x is     
want$ = use imm$iately4 ,9 ! latt] case1
 h[ev]1 x w be "s fifte5 m9utes or s    
be=e ! tube w atta9 its work+           
temp]ature4 ,asbe/os l9+s gradually     
become worn & ragg$1 & small flakes are 
apt to deta* !mselves & fall d[n into ! 
burn]1 :i*1 ( c\rse1 prev5ts ! flame    
play+ z x %\ld ar\nd ! tube4 ,9 su*     
cases x is n always necess>y to fit a   
new l9+2 if ! *imney is remov$1 ! loose 
flakes %ak5 out & ! asbe/os well damp$ &
 patt$ d[n ) a wood5 or /eel foot-rule  
or o!r suitably %ap$ tool1 x w be fit = 
ano!r long spell ( "w4  ,! nickel or    
hecknum tubes are treat$ 9 ! same mann] 
z ! iron1 b1 z we m5tion$ be=e1 are m   
durable1 b require m heat+ to get !m up 
to a workable temp]ature4 ,_! great]    
fir/ co/ is comp5sat$ to "s ext5t by    

mak]s 9 "s cases gu>antee+ !m = six     
mon?s4  ,( ! porcela9 ignition devices1 
we w deal ) ! d\ble-end$ tube fir/1 x   
be+ ! m commonly us$ ( ! two 9 ?is      
c\ntry4 ,?is =m ( tube is usually ab\t  
#c 94 long1 #a_/b 94 diamet]1 & op5 at  
bo? ends4 ,x may be m\nt$ 9 a metal     
ca/+1 9 =m n unlike ! small gas /oves = 
heat+ sold]+ irons4 ,x is heat$ ! great]
 "p ( its l5g? by a c\ple ( r[s ( gas   
jets1 & is frequ5tly surr\nd$ by an     
asbe/os l9+4 ,! :ole arrangem5t is 9    
reality a t9y furnace4 ,:5 9 position = 
work+1 "o end ( ! tube is op5 to !      
ignition passage lead+ & communicat+ ) !
 combu/ion *amb]1 :ile ! o!r end is     
seal$1 ?r\gh butt+ up aga9/ a metal cap 
or plate4 ,an asbe/os wa%] is int]pos$  
betwe5 ! tube at ea* end & ! metal x    
be>s aga9/1 ?us mak+ a m or less        
flexible jo9t4 ,a ?umb screw is arrang$ 
at ! outside end ( ! tube1 by means (   
:i* pressure c be appli$ to clamp x up  
betwe5 ! wa%]s to ! desir$ ext5t4 ,"s   
c>e has to be ex]cis$ 9 adju/+ ?is =m ( 

tube = runn+4 ,:5 heat$ to ! work+      
temp]ature x1 ( c\rse1 exp&s1 s t1 if   
tight5$ up too mu* :5 cold1 x is "u a   
fairly high compression2 & :5 ! eng9e is
 />t$1 & ! explosion takes place1 x n   
infrequ5tly bur/s1 if !re is n suffici5t
 give 9 ! wa%]s to all[ = ! expansion4  
,on ! o!r h&1 if n clamp$ up suffici5tly
 tight to />t )1 :5 ! explosion occurs1 
! wa%] at "o or ea* end is bl[n out4    
,?is adju/m5t has to be made to a       
nicety1 &1 al?\gh a some:at difficult   
matt]1 success may be atta9$ aft] "o or 
two trials4 ,x is advisable1 aft] a new 
tube has be5 put 91 to />t up ! eng9e   
g5tly1 i4e41 ) less ?an ! normal supply 
( gas1 & increase to ! full am\nt       
gradually :il/ runn+4 ,?is may be done  
by simply op5+ ! gas-cock on eng9e      
p>tially 9 ! fir/ place4  ,! s+le-end$  
porcela9 tube is n s well kn[n "h z on !
 cont95t2 :y1 we _c say2 c]ta9ly x is   
pref]able 9 e way4 ,we give a few       
illu/rations1 %[+ ! me?od ( us+ ?is     
tube4  ,figs4 #af & #ag %[ ! g5]al      

arrangem5t ( tube & *imney & ! mann] 9  
:i* !y are fix$ to ! cyl9d]4 ,! device  
consi/s prim>ily ( ?ree p>ts--! body or 
*imney ,b1 ! cov] ,c1 & ! tube itself   
,t4 ,! body is a light iron ca/+1 c>ri$ 
by a c\ple ( /uds ,,ss1 :i* are ei!r    
screw$ into ! fir+ block ,f1 or direct  
into ! metal ( ! cyl9d] ca/+ if no      
fir+-block is us$2 ! latt] may v well be
 disp5s$ ) 9 ! small]-siz$ eng9es4  ,!  
tube is made ( ?9 porcela91 slightly    
bell-m\!d at its op5 end1 & is m\nt$ 9 a
 ?ick metal wa%] ,w1 z %[n 9 fig4 #ah 9 
section1 ! jo9t be+ made ) a little     
asbe/os pap]1 moi/5$4  ,! block ,f & !  
face ( ! body ,b 7fig4 #af7 are recess$ 
to take ! wa%] ,w easily1 b ! dep? ( bo?
 recesses tak5 toge!r mu/ be ab\t #a_/af
 94 less ?an ! ?ickness ( ! wa%] ,w2    
?us1 :5 ! tube is plac$ 9 position      
betwe5 ! body ,b & ! block ,f1 & ! =m]  
screw$ up by means ( ! two nuts1 z %[n 9
 ! figure #af1 ! effect is to clamp !   
wa%] :i* c>ries ! tube1 b n ! porcela9  
tube itself4  ,illu/ration3 ,,fig4 #af4 

,illu/ration3 ,,fig4 #ag4  ,illu/ration3
 ,,fig4 #ah4  ,! latt] is left p]fectly 
free to exp&2 & yet1 ow+ to its p>ticul>
 %ape1 ! pressure 9 ! cyl9d] dur+ !     
compression & explosion /roke only t5ds 
to make ! jo9t betwe5 ! tube & wa%] m   
secure4 ,! action ( ?is ignition device 
dep5ds ^u ! tube heat] ,h1 :i* is m]ely 
a small buns5 burn]1 ! flame ( :i*      
imp+es on ! tube at "o p>ticul> spot1   
rais+ x to a v high temp]ature--almo/   
:ite heat4 ,mo/ ( my read]s w "k !      
=mation ( ! buns5 flame4 ,x 9 compos$ ( 
two di/9ct zones4 ,! inn] "o1 m>k$ ,a 9 
fig4 #ah1 is a p]fectly cold "p ( !     
flame1 & appe>s to be a pale-blue col\r$
 cone4  ,x is ! out] zone :i* is ! hot  
portion ( ! flame1 h5ce ?is "p only mu/ 
be all[$ to play on ! tube4 ,! tip ( !  
blue cone ,a mu/ be kept ab\t #a_/d 94  
bel[ ! tube1 9 ord] to ensure ! hotte/  
"p ( ! flame imp++ precisely :]e ! heat 
is requir$4  ,! total l5g? ( ! :ole     
flame is1 to a c]ta9 ext5t1 immat]ial2  
b1 g5]ally speak+1 x %\ld be adju/$ s t 

! l5g? ( ! inn] cone ,a is ab\t #a 94 or
 #a-a_/d 94 ,! same me?ods :i* we       
describ$ 9 ! e>ly "p ( ?is *apt] c be   
employ$ 9 ! adju/m5t ( ?is burn]1 b "s  
c>e %\ld be ex]cis$ to get ! correct    
flame l5g?4  ,! result ( all[+ ! cold "p
 ( ! flame to imp+e on ! tube is        
obs]vable 9 fig4 #ah4 ,! black spot     
indicat$ on ! draw+ actually appe>s z a 
black or sooty spot :5 look+ at ! tube  
"u ^! conditions2 b 9 reality no        
discoloration :atev] takes place1 ! spot
 disappe>+ imm$iately ! cone ,a is made 
%ort]1 or ! burn] ,h l[]$ 9 ! *imney ,b1
 s t ! tip ( ,a is j bel[1 & does n t\* 
! tube at all4  ,! adju/m5t ( ! l5g? (  
cone ,a may be accompli%$ 9 two         
ways--7#a7 by keep+ ! supply ( gas      
con/ant1 & v>y+ ! am\nt ( air admitt$ at
 ap]ture ,k1 fig4 #ah2 7#b7 by keep+ !  
supply ( air con/ant1 & v>y+ ! am\nt (  
gas admitt$ ?r\gh nipple ,n4 ,! fir/    
me?od is to be pref]r$ :5 x is necess>y 
to make any slight adju/m5t due to !    
v>iation ( gas pressure dur+ ! day1 &   

may be accompli%$ by fitt+ a small slid+
 %ield ,g1 z %[n 9 ! figs4 #af & #ag1 & 
mov+ x r\nd s t x cov]s1 m or less1 !   
ap]ture ,k4 ,?us ! l5g? ( cone ,a may be
 adju/$ to a nicety 9 a v few seconds4  
,?is %ield keeps all draughts & puffs ( 
w9d f ! fly-:eel away f ! ap]ture1 &    
helps ! flame to burn v /eadily4 ,9 !   
fir/ place1 ( c\rse1 ! flame w be       
regulat$ by op5+ out or tapp+ up !      
nipple ,n 7an enl>g$ sket* ( :i* is giv5
 9 fig4 #ad71 s t cone ,a is j ab\t     
#a-a_/d 94 long :5 air ap]ture is full  
op52 b once ?is is done1 any future     
adju/m5t c be made by ?rottl+ !         
air-supply1 or rais+ or l[]+ ! burn]    
bodily1 ! set screw keep+ x 9 any desir$
 position 7see fig4 #ag74  ,f ! =ego+   
rem>ks x w be se5 t ! mo/ notewor?y     
features ( ?is =m ( ignition are ! ease 
& c]ta9ty ) :i* ! tube c be fix$ 9 a few
 mom5ts2 t :5 ! two nuts on ! /uds ,,ss 
h be5 tight5$ up !re is no likelihood ( 
! jo9ts be+ bl[n1 =1 z we said be=e1    
only ! metal wa%] is clamp$ up1 !       

porcela9 tube itself be+ z free to exp& 
z x 0 be=e4 ,x is also at once obvi\s :5
 any adju/m5t ( ! flame is necess>y2 !re
 ne$ be no unc]ta9ty z to :e!r ! tube is
 hot en\gh or n4     ,,*apt] ,v         
,,magneto ,,ignition   ,! ?ird =m (     
ignition we h to deal ) is ! electric4  
,!re are a great numb] ( diff]5t types  
made & us$1 b = gas-eng9e use p]haps t  
kn[n z ! magneto ignition is ! mo/      
satisfactory4 ,) ?is =m1 nei!r          
accumulators1 dry batt]ies1 or sp>k     
coils are requir$1 & consequ5tly a      
great] simplicity is arriv$ at ?an w\ld 
o!rwise be ! case4  ,9 fig4 #ai we %[   
diagrammatically ! ord9>y =m ( magneto  
ma*9e4 ,virtually x is a small dynamo   
:i* is fix$ to ! side ( cyl9d] ca/+1 &  
is op]at$ 9 ! mann] %ortly to be        
describ$4 ,z we d n propose to ent] into
 m ?an a brief explanation ( :y & h[ ?is
 app>atus g5]ates curr5t to produce !   
requir$ sp>k1 p]haps a simple analogy w 
make matt]s mo/ intelligible to any     
read] n well acqua9t$ ) electrical      

ph5om5a4 ,we "k t :5 a curr5t (         
electricity is fl[+ 9 a wire1 & ! wire  
be sudd5ly brok51 a sp>k w occur at !   
po9t ( breakage4 ,?is fact may be obs]v$
 9 an ord9>y electric bell :5 r++2 at ! 
tip ( ! contact break] a numb] ( t9y    
sp>ks may be se5 to occur1 due to !     
rapid make & break ( ! curr5t fl[+ 9 !  
circuit4 ,precisely ! same action takes 
place 9 our magneto-ignit]1 b1 in/ead ( 
a multitude ( t9y sp>ks1 we produce "o  
at a "t1 at def9ite int]vals1 viz41 at !
 comm5cem5t ( ea* explosion /roke4      
,illu/ration3 ,,fig4 #ai4  ,9 ! lat] =m 
( magneto ma*9es !re is a s(t iron      
sleeve betwe5 ! magnet poles & !        
armature4 ,! =m] is connect$ to a sy/em 
( lev]s by :i* a reciprocat+ motion is  
imp>t$ to x by means ( a suitably       
arrang$ cam on ! side %aft4 ,x has be5  
f\nd t bett] results are obta9$ by caus+
 ! magnetic field to move relative to ! 
armature w9d+ ?an to move ! latt] ?r\gh 
a /ation>y field4 ,ref]5ce to !         
diagrams1 figs4 #bj & #ba1 w make ?is   

cle>4  ,9 fig4 #ai ! cam ,c is %[n j on 
! po9t ( all[+ ! lev] ,l to fly back    
into its normal position1 due to !      
action ( ! spr+s compris+ a da%pot ,s4  
,z ! cam rotates1 x pu%es ! lev] ,l to !
 left1 ! sleeve 7or virtually ! armature
 ,a7 is also rotat$ ?r\gh a portion ( a 
revolution comp>atively sl[ly2 b z soon 
z ,l is releas$1 ! sleeve 7or armature7 
flies back aga9 almo/ in/antane\sly & = 
! mom5t is g5]at+ a curr5t 9 ! same     
mann] z w\ld any ord9>y cont9u\s curr5t 
dynamo4  ,illu/ration3 ,,fig4 #bj4      
,illu/ration3 ,,fig4 #ba4  ,at ! in/ant 
! maximum curr5t is be+ g5]at$1 !       
circuit is brok5 by means ( ! contact   
break] ,d1 fig4 #ai1 :i* we %[ 9 detail 
9 fig4 #bb4 ,! latt] is m\nt$ on ! end (
 ! combu/ion *amb]1 & consi/s ( two     
p>ts1 ,d & ,p4  ,illu/ration3 ,,fig4    
#bb4  ,d is an easy fit 9 ! hole bor$ to
 receive x1 & has a mu%room valve head &
 seat+1 z %[n1 s t x moves readily :5   
/ruck by ! projection ,e on ! rod ,r    
7fig4 #ai72 b yet1 act+ 9 ! mann] ( a   

non-return valve1 x all[s no gas to     
escape :5 ! explosion takes place 9 !   
cyl9d]4 ,d is !re=e 9 direct metallic   
communication ) ! eng9e frame & e>?4  ,p
 is a fix$ metal p91 c>efully insulat$ f
 all contact ) ! eng9e frame & e>?4 ,to 
?is p9 "o end ( ! armature w9d+ is      
connect$1 :il/ ! o!r end is connect$ to 
! eng9e frame4  ,?us a clos$ circuit is 
=m$1 & :5 ! curr5t is g5]at$ x fl[s f "o
 t]m9al ( magneto ?r\gh wire to p9 ,p1  
on to ,d1 ?r\gh ,d to e>? 7i4e41 eng9e  
frame71 & s back to o!r t]m9al on       
magneto4  ,& z ! circuit is brok5 betwe5
 ,d & ,p1 we obta9 a sp>k1 z previ\sly  
expla9$1 :i* may be tim$ to take place  
by adju/+ ! position ( cam ,c on side   
%aft relatively to ! position ( pi/on4  
,x may be said t ! position ( !         
magneto-ignit] is immat]ial2 x w be fix$
 9 diff]5t positions on diff]5t types ( 
eng9es1 & s long z ! op]at+ me*anism is 
simple & effective1 i4e41 z direct z is 
practicable1 x works well1 & requires   
little att5tion4 ,! tim+ ( ! sp>k w be  

dealt ) 9 ! *apt] on ,cams & ,valve     
,sett+s4     ,,*apt] ,,vi  ,,gov]n+   ,!
 devices = gov]n+ ! spe$ ( ! eng9e may  
be divid$1 broadly speak+1 into two     
classes--! in]tia or hit & miss gov]nor1
 & ! c5trifugal4 ,( ! latt] type we w   
give an in/ance fir/4 ,9 figs4 #bc & #bd
 ! gov]nor ge> is %[n diagrammatically1 
consi/+ ( a c\ple ( weights ,,ww susp5d$
 f a v]tical sp9dle4 ,^! fly ap>t :5    
caus$ to revolve by ! bevel :eel ge>+   
,,bb1 & raise ! sleeve ,s to a great] or
 less] ext5t4 ,a recess 9 ! latt]       
engages a lev] arm ,l1 ?r\gh :i* !      
v]tical movem5t ( ! sleeve ,s is conv]t$
 into a horizontal movem5t ( ! sleeve   
,t4 ,! latt] is c>ri$ by ! valve lev]   
,p1 & is virtually a roll] :i* engages )
 "o or o!r ( ! /eps ( ! cam ,c1 accord+ 
to ! spe$ ( ! eng9e4 ,! object ( ?is    
arrangem5t is to keep ! ratio ( air to  
gas uni=m ?r\gh\t all v>iations ( load4 
,! gas & air valve are %[n z bo? be+    
op]at$ by ! same lev] ,p1 ! accurate    
tim+ ( ! latt] be+ obta9$ by means ( set

 screws4  ,illu/ration3 ,,fig4 #bc4     
,illu/ration3 ,,fig4 #bd4  ,messrs      
,d\gill  ,co4's eng9es are fitt$ ) a /ep
 d[n cam & gov]nor su* z ?is4 ,!        
c5trifugal gov]nor is (t5 arrang$ s t   
in/ead ( ! *>ge be+ m]ely r$uc$ 9       
volume1 ! :ole *>ge is cut out1 & no    
explosion :atev] takes place4 7,9 ?is   
respect ! same results are obta9$ z :5 a
 hit & miss gov]nor is us$1 & ! latt] =m
 !re=e is to be pref]r$1 especially on  
small eng9es1 :]e ! diff]5ce betwe5 !   
indicat$ p[] & ! brake p[] is always1   
ev5 "u ! be/ conditions1 fairly great47 
,9 ?is case ! gov]nor lev] only op]ates 
! gas valve2 ! air valve be+ op5$ on e  
*>g+ or suction /roke1 :e!r gas is      
admitt$ or n4  ,ano!r application ( !   
c5trifugal gov]nor is to susp5d a       
di/ance piece on ! end ( ! gov]nor lev]1
 s t at normal spe$ ?is di/ance piece is
 int]pos$ betwe5 ! gas valve sp9dle & ! 
lev] op]at+ x4 ,9 t case ! gas valve w  
be op5$4 ,b if ! spe$ is above ! normal1
 ! di/ance piece w be rais$ cle> ( !    

valve sp9dle1 & ! op5+ me*anism 7driv5  
by a cam on ! side %aft7 w simply move  
=w>d & rec$e aga9 )\t ev] t\*+ ! gas    
valve4  ,!re are any numb] ( movem5ts   
:i* h be51 & !re are _m m :i* c\ld be1  
devis$ to give ! same result2 & x dep5ds
 pr9cipally ^u ! =m ( eng9e 9 "q :i*    
device we adopt4  ,! simple/ & mo/      
direct action is1 h[ev]1 always ! be/2  
complicat$ me*anism is to be deprecat$1 
especially on small eng9es4 ,= ?is      
reason is ! in]tia gov]nor m g5]ally    
fitt$ to su* eng9es4  ,illu/ration3     
,,fig4 #be4  ,a simple =m ( ?is gov]nor 
is %[n 9 fig4 #be4 ,! gas valve ,v is   
%[n on its seat+4 ,x is screw$ into a   
peck] block ,b1 & p9n$ z %[n4 ,! latt]  
%\ld be ( ca/ /eel1 temp]$ to a /raw    
col\r2 or if mild /eel or iron is us$1 x
 mu/ be well case-h>d5$1 9 ord] to resi/
 we>4 ,! peck] ,p 7also temp]$ h>d7 is  
m\nt$ on ! ca/-iron weight ,w1 :i* 9    
turn is pivot$ on ! valve lev] ,l4 ,x w 
be se5 t ! weight ,w 7:i* is only held 9
 ! position %[n by ! spr+ ,s7 w t5d to  

lag beh9d :5 a sudd5 upw>d motion is    
imp>t$ to ! lev] ,l4 ,?us x dep5ds ^u ! 
degree ( sudd5ness ) :i* ,l moves :e!r !
 peck] ,p rema9s 9 ! same relative      
position to ! lev] z ! latt] travels    
upw>ds & engages ) ! peck] block ,b1 or 
:e!r x misses x & simply slides ov] !   
face ( ! block4 ,! adju/m5t ( ! spr+ ,s 
is effect$ by screw+ up or slack+ out ! 
mill$ nuts ,t2 & on ! degree to :i* ?is 
spr+ is compress$ dep5ds ! s5sitiv5ess (
 ! gov]nor1 & consequ5tly ! spe$ ( !    
eng9e4 ,to obta9 accurate & /eady gov]n+
 ) ?is type ( me*anism x is ess5tial t !
 weight be p]fectly free on its sp9dle1 
& t no?+ b ! spr+ ,s holds1 or t5ds to  
hold1 x 9 ! position %[n4 ,on ?is acc\nt
 x is advisable to provide a lip on !   
peck] block1 z %[n1 to keep ! area (    
contact z small z possible4 ,?is        
effectually prev5ts any /ick+1 %\ld a   
sup]fluity ( oil happ5 to get on ei!r   
block or peck]4 ,= simil> reasons !re   
%\ld be "s cle>ance betwe5 ,a & ! peck]1
 i4e41 ! latt] %\ld only be> at "o po9t 

& n b$ flat aga9/ ,a4  ,ano!r =m (      
in]tia gov]nor is %[n 9 fig4 #bf ( ! hit
 & miss type1 :i* is employ$ by ,messrs 
,capel  ,co4 on _m ( _! eng9es4  ,x     
consi/s ( ?ree ma9 p>ts--! brass arm ,l 
c>ri$ on a /ud ,d1 on :i* x is free to  
move2 ! weight ,w1 :i* c>ries ! peck] ,p
 pivot$ at ! upp] end ( ,l2 & ! peck]   
block ,b1 :i* engages ! peck] :5 ! eng9e
 requires a *>ge ( gas4  ,! gov]n+      
action is dep5d5t ^u ! %ape ( ! op]at+  
cam f ,x to ,y4 7,9 ! case already dealt
 )1 ! lev] ,l s]ves to op]ate bo? air & 
gas valves1 & s "o cam only is necess>y2
 b 9 ?is in/ance ! gas valve is op]at$  
by a sep>ate cam1 & a great] nicety (   
adju/m5t is obta9able47  ,illu/ration3  
,,fig4 #bf4  ,if ! spe$ ( ! eng9e is    
suffici5tly high1 ! arm ,l is ?ru/ =w>d 
at su* a rate t ! weight ,w t5ds to lag 
beh9d1 ) ! result t ,p is rais$ above ! 
not* 9 ,b1 z %[n by ! dott$ l9es 9      
draw+4 ,on ! o!r h&1 :5 ! spe$ is too   
l[1 ! arm ,l w n be ?ru/ =w>d ) s great 
a degree ( sudd5ness1 ! weight ,w w h "t

 to move ) ,l1 & ! relative position (  
,w & ,p to ,l w rema9 ! same4 ,h5ce1 9 !
 fir/ case1 :5 a fur!r =w>d movem5t is  
giv5 to ,l by ! cam1 ! peck] ,p is cle> 
( ,b1 & omits to op5 ! gas valve ,v2 9 !
 second case1 ,p engages ) ,b1 & ! gas  
valve is held op5 dur+ ! "t ! portion ( 
cam ,y to ,z is pass+ ov] ! roll] ,r on 
arm ,l4  ,! great drawback to "s =ms (  
gov]nors is n t !y fail to gov]n well :5
 new1 b t no provision is made to ensure
 !m work+ /eadily :5 a bit worn4 ,! %ape
 ( ! cam has ev]y?+ to d ) ! regul>     
work+ ( ?is =m ( gov]nor4  ,suppos+ our 
cam 0 ( ! %ape %[n 9 fig4 #bg1 i4e41 !  
gov]n+ & op5+ portion all 9 "o curve1 x 
w\ld cause ! peck] to move bo? =w>d & 9 
an upw>d direction at ! same "t1 s t at 
! mom5t ( engag+ ,b1 ,p might /ill be   
mov+ 9 an upw>d direction1 :i* w\ld     
cause unc]ta9ty ( action1 especially if 
! tips ( ! engag+ memb]s 7 at all blunt 
?r\gh we>2 &1 9 all probability1 ,p w\ld
 fly (f ,b aft] p>tially op5+ ! gas     
valve4  ,?is behavi\r is v undesirable1 

z ! small quantity ( gas s admitt$ to ! 
cyl9d] is q useless1 & a %e] wa/e is    
incurr$4 ,) ! gov]n+ arrangem5t %[n 9   
fig4 #bf1 ?is tr\ble does n exi/4 ,! cam
 is s design$ t ! fir/ rise f ,x to ,a  
det]m9es :e!r or n ! valve is to be     
op5$2 ! curve f ,a to ,y is /ruck f !   
c5tre ( ! side %aft2 ?us1 dur+ t portion
 ( ! revolution ! arm ,l is /ation>y1 & 
! peck] at ! same in/ant takes up a     
def9ite position ei!r 9 ! not* 9 ,b or  
on top ( x1 & is ready to op5 ! valve if
 ! spe$ ( ! eng9e is su* z to require an
 explosion1 or simply to slide ov] ! top
 ( ,b1 all[+ ! valve to rema9 clos$4 ,x 
is mo/ int]e/+ to obs]ve ! action ( ?is 
gov]nor2 :5 an eng9e fitt$ ) "o is runn+
 v sl[ly1 ! ?ree di/9ct movem5ts ( !    
peck] ,p may be cle>ly disc]n$ z !      
respective portions ( ! cam pass ov] !  
small roll] ,r4  ,illu/ration3 ,,fig4   
#bg4     ,,*apt] ,,vii  ,,cams ,,&      
,,valve ,,sett+s   ,) ! gas1 z ) any o!r
 k9d ( eng9e1 ! valve sett+s are (      
prim>y importance4 ,on v small eng9es x 

is (t5 ! case t only ! exhau/ valve is  
op]at$ me*anically4  ,aga91 !re are     
sev]al well-kn[n makes :i* op]ate ! gas 
& exhau/ me*anically :ile ! air valve is
 op5$ by suction alone4 ,?\gh op9ions   
diff] z to :i* is ! be/ c\rse to take1  
!re c be little d\bt t1 ) all ?ree      
valves me*anically op]at$1 a great]     
nicety ( adju/m5t is obta9able ?an w\ld 
be o!rwise possible4 ,& provid$ ! work+ 
p>ts are neatly made & f9i%$1 !y w take 
b little p[] to drive !m2 & su* loss    
w\ld be comp5sat$ by ! additional p[] & 
effici5cy obta9$ f ! eng9e1 due to      
satisfactory & correct adju/m5t4  ,9    
fig4 #bh we give a diagram %[+ ! exact  
positions ( ! crank :5 ! gas1 air1 &    
exhau/ valves op5 & close respectively1 
"u normal conditions ( work+4 ,! solid  
circle repres5ts ! fir/ revolution ( !  
crank %aft1 />t+ f ! comm5cem5t ( !     
suction /roke1 & ! dott$ circle ! second
 revolution1 dur+ :i* ! explosion &     
exhau/ /rokes take place2 ! dott$       
horizontal l9e %[s ! position ( crank at

 ! back & front dead c5tres4  ,z a cle> 
conception ( :y c]ta9 ?+s happ5 "u c]ta9
 conditions is mo/ desirable1 we w fir/ 
describe ! op]ation ( m>k+ (f ! cams :i*
 op]ate ! respective valve lev]s1 & !n  
discuss ! effect ( v>i\s sett+s ( !     
valves on ! runn+ ( ! eng9e4            
,illu/ration3 ,,fig4 #bh4  ,assum+ t we 
are /ill deal+ ) ! ,otto cycle eng9e1 ! 
cam or side %aft w revolve at precisely 
half ! spe$ ( ! crank %aft4 ,?is #b to  
#a motion is obta9$ by means ( too!d    
:eels1 or a screw ge>4 ,9 ! =m] case1   
:]e pla9 or bevel cog-:eels are employ$1
 ! "o fix$ on ! crank %aft mu/ be       
exactly half ! diamet] ( ! "o on ! side 
%aft1 i4e41 x mu/ h "o half ! numb] (   
tee?4 ,on ! o!r h&1 if a screw ge> is   
us$1 ! relative diamet]s ( ! two :eels  
may v>y1 b ! pit* ( ! tee? on ! "o mu/  
be twice t ( ! o!r4 ,^! :eels sometimes 
h ! tee? or ?read =m$ 9 ! ca/+1 &       
sometimes !y are cut aft] a pla9 ca/+   
has be5 made4 ,! latt] k9d are1 ne$less 
to say1 bett] ?an ! =m]1 :i* (t5 require

 fil+ up 9 ord] to make e too? alike1 & 
ensure sweet runn+4  ,we "k already 9   
:at positions our crank has to be at !  
op5+ & clos+ ( ! ?ree valves1 & ) ! aid 
( ! diagram1 fig4 #bh1 we c det]m9e !   
size ( ! cams4 ,9 fig4 #bi1 ,s is ! side
 %aft to :i* ! cams h to be key$1 ,r !  
roll] on valve lev]1 ! latt] be+        
repres5t$ by ! c5tre l9es ,,ll1 z all we
 require to f9d is ! motion ?is lev] w  
transmit to ! valve1 ! sp9dle ( :i* is  
%[n at ,v4  ,fig4 #cj %[s               
diagrammatically ! position ( crank at !
 op5+ & clos+ ( ! air valve4 ,f ?is we  
see t ! angle ?r\gh :i* ! crank travels 
dur+ ! "t ! air valve is op5 is equal to
 ! obtuse angle ,,abc4 ,n[1 z ! side    
%aft ,s revolves at half ! spe$ ( crank1
 x is obvi\s t ! =m] w travel ?r\gh only
 half t angle 9 ! same space ( "t1 i4e41
 ?r\gh an angle equal to ,,abd4 ,we c n[
 transf] ?is angle on to ,s1 fig4 #bi1 &
 draw two l9es ,,se1 ,,sf1 cutt+ a      
circle ,,ghj1 repres5t+ ! back ( ! cam1 
:i* latt] passes 9 front ( ! roll] ,r   

)\t caus+ any movem5t ( ! lev] ,l4      
,illu/ration3 ,,fig4 #bi4  ,illu/ration3
 ,,fig4 #cj4  ,illu/ration3 ,,fig4 #ca4 
,x w be se5 t by draw+ a l9e =m+ a      
tang5t to ! circle ,,ghj at ,f & ano!r  
at ,e1 & produc+ ^!1 !y w meet at po9t  
,k4 ,consequ5tly1 z ! side %aft rotates 
9 ! direction indicat$1 ! lev] ,l w beg9
 to op5 ! valve ,v :5 ! cam is 9 !      
position %[n 9 fig4 #bi1 rea* a maximum 
op5+ at ,k1 & f9ally close :5 ! cam has 
mov$ s t po9t ,e is n[ :]e ,f 04 ,) a   
cam ( ?is %ape1 h[ev]1 a consid]able    
portion ( ! /roke w\ld h pass$ be=e !   
valve 0 rais$ any appreciable di/ance (f
 its seat2 x w\ld only be fully op5 = an
 in/ant1 viz41 :5 ,k 0 pass+ ov] ,r1 &  
w\ld beg9 to close aga9 directly4       
,moreov]1 if ! eng9e 7 runn+ at ev5 a   
sl[ spe$1 ! motion imp>t$ to lev] ,l    
w\ld be indef9ite2 & ?is1 especially if 
! gov]nor is fitt$ to ! air valve lev]1 
z 9 fig4 #be1 is v undesirable4 ,!re=e1 
to obta9 a def9ite op5+ we mu/ set out !
 cam1 z %[n 9 fig4 #ca4 ,9 ?is diagram !

 roll] is %[n /&+ cle> ( ! back ( cam by
 ab\t #a_/af 94 ,a l9e ,,mn is !n drawn1
 =m+ a tang5t to bo? roll] ,r & circle  
,,ghj at po9ts ,f & ,o respectively4    
,?is gives u ! op5+ portion ( cam4 ,!n f
 ! c5tre ,s ) radius ,,sf describe ! arc
 ,,fe 7%[n dott$ 9 fig4 #ca71 & set (f !
 angle requir$ 7,,abd1 fig4 #cj71 z     
previ\sly expla9$4 ,?r\gh po9t ,e draw a
 l9e =m+ a tang5t to circle ,,ghj1 &    
produce x t[>ds ,p4 ,?is l9e gives u !  
clos+ portion ( cam4 ,! di/ance ,w is ( 
c\rse v>iable1 accord+ to ! am\nt ( lift
 we give ! valve4 ,by comp>+ ^! two     
diagrams x w be se5 t 9 bo? cases !     
valve w be op5$ ! same l5g? ( "t1 b 9   
fir/ case ! motion w be indef9ite &     
unc]ta94 ,9 practice ! corn]s are r\nd$ 
(f some:at1 9 ord] to obta9 a /eady     
motion2 & :5 ! air cam is also ! gov]n+ 
cam1 x is advisable to r\nd (f ! op5+   
face1 z indicat$ 9 fig4 #cb4 ,^u ! %ape 
( ?is face bo? ! s5sitiv5ess & ! life ( 
! gov]nor ge> dep5ds4 ,if x is nicely   
r\nd$ (f1 giv+ a gradual rise1 v little 

t5sion 7or compression1 z ! case may be7
 ( ! controll+ spr+ w be necess>y to    
give ! requir$ spe$ to eng9e2 :]eas1 if 
! rise is sudd51 ! spr+ w h to be screw$
 up tight]1 &1 if unev5 & lumpy 7i4e41 n
 a fair curve71 ! result w1 ( c\rse1 be 
erratic gov]n+4  ,illu/ration3 ,,fig4   
#cb4  ,a c]ta9 am\nt ( cle>ance %\ld    
always be provid$ betwe5 ! roll] & !    
back ( cam 7comp>e figs4 #bi & #ca71 t  
is1 ! roll] %\ld n be> aga9/ ! cam1     
except dur+ t portion ( ! /roke 9 :i* x 
is actually op]at+ ! valve1 viz41 f ,f  
to ,e 7fig4 #ca74 ,a small /op int]pos$ 
betwe5 ! lev] & "s conv5i5t "p ( !      
eng9e1 su* z ! side-%aft bracket be>+1  
answ]s ?is purpose4  ,illu/ration3      
,,fig4 #cc4  ,illu/ration3 ,,fig4 #cd4  
,! size & %ape ( ! exhau/ cam is f\nd 9 
! same mann] z above describ$2 ! angle  
?r\gh :i* x op]ates is great] ?an t ( ! 
air cam1 & is %[n 9 fig4 #cc4 ,a fair   
m>g9 %\ld be all[$ = fil+ or ma*9+ ^!   
ca/+s up2 ! %ape & sizes arriv$ at by ! 
above describ$ me?od be+ f9i%$          

measurem5ts4 ,fig4 #cd gives ! outl9e ( 
an exhau/ cam work$ out f ! sett+       
diagram1 fig4 #cc4  ,illu/ration3 ,,fig4
 #ce4  ,illu/ration3 ,,fig4 #cg4        
,illu/ration3 ,,fig4 #da4  ,illu/ration3
 ,,fig4 #db4  ,we may n[ consid] !      
relative positions ^! two cams w occupy 
:5 key$ up on ! side %aft4 ,assum+ t we 
h bo? cams f9i%$ to ! prop] %ape & size1
 & ! keyway cut 9 ! side %aft1 we c     
comm5ce to m>k (f ! position ( keyway 9 
! air cam4 ,) ! crank 9 ! position %[n 9
 fig4 #ce1 ! air cam is slipp$ on to !  
side %aft & br\ght to ! position %[n 9  
fig4 #cb4 ,! keyway be+ already cut 9 ! 
side %aft1 ! position = t 9 ! cam may be
 scrib$ (f1 z %[n by dott$ l9es 7fig4   
#cb71 ! cam remov$1 & ! keyway cut4 ,x  
is z well1 h[ev]1 to *eck ?is m>k by    
turn+ ! crank r\nd to position %[n 9    
fig4 #cg1 i4e41 ! clos+ ( air valve4 ,! 
side %aft w also turn ?r\gh exactly half
 ?is angle1 s t :5 ! cam is aga9 slipp$ 
on ! latt]1 ! scrib] m>ks & keyway 9    
%aft %\ld be exactly 9 l9e1 z !y 7 9    

fig4 #cb1 & ! fall ( ! cam--! clos+     
portion--%\ld j be t\*+ roll] ,r1 b n   
suffici5t to keep ! valve op5 7see fig4 
#ch74 ,! slighte/ movem5t ( ! crank f   
?is po9t 9 a =w>d direction %\ld result 
9 a little play be+ felt 9 ! lev] ,l1   
assum+ t ! cam is also mov$ j en\gh to  
keep ! scrib] m>ks 9 l9e ) ! exi/+      
keyway4  ,illu/ration3 ,,fig4 #cf4      
,illu/ration3 ,,fig4 #ch4  ,illu/ration3
 ,,fig4 #ci4  ,by ^! op]ations x w be at
 once evid5t :e!r ! cam is too l>ge or  
too small4 ,suppos+ x is too small1 we w
 obta9 two sets ( m>ks indicat+ !       
position ( keyway1 z %[n 9 fig4 #ci1 & x
 is obvi\s t we mu/ give ! lev] less    
play by screw+ up ! set screws %[n 9    
fig4 #aa4 ,! effect ( ?is is to cause ! 
valve to op5 e>li] & close lat] ?an x   
w\ld if ! play 7 great]2 z x w\ld 7 !   
op]at+ portion ( cam l>g]4 ,a m9imum    
am\nt ( play mu/ always be all[$1 h[ev]4
 ,:5 two sets ( m>ks are obta9$1 ! mean 
mu/ be tak5 & ! keyway cut z %[n by !   
?ick l9es 9 fig4 #ci4 ,! exhau/ cam 9   

l>g] eng9es is usually made ) a swell+  
on ! op5+ portion1 z %[n 9 fig4 #dj1 s t
 ! valve is v slightly op5$ "s "t be=e !
 crank has rea*$ ! position %[n 9 fig4  
#da4 ,fig4 #db %[s position ( crank at !
 close ( exhau/ valve1 & ! two          
la/-m5tion$ diagrams correspond ) ! two 
positions 9 :i* ! exhau/ cam is %[n 9   
fig4 #cd4 ,! small lump on ! back (     
exhau/ cam1 fig4 #dj1 is only requir$ on
 eng9es above #c ,b4,h4,p4 to relieve ! 
compression on ! compression /roke :5   
/>t+ up4 ,by mov+ ! roll] ,r on valve   
lev] longitud9ally1 s t x engages bo?   
p>ts ( cam z !y pass 9 front ( x1 !     
exhau/ valve is held op5 dur+ a small   
portion ( ! compression /roke1 usually  
clos+ :5 ! crank has rea*$ ! bottom     
c5tre4  ,ref]r+ aga9 to fig4 #bf1 ?is   
gas or gov]nor cam may be set out1 & !  
keyway m>k$ on ! same pr9ciple z already
 describ$ = ! air & exhau/ valves4 ,an  
end view ( ! ?ree cams key$ up on ! side
 %aft is giv5 9 fig4 #dj;,a4 ,9 small   
eng9es x is conv5i5t to h ! air & exhau/

 cams made 9 "o ca/+1 :5 "o key only w  
be requir$4 ,on "s eng9es1 in/ead (     
employ+ a movable roll] or valve lev]1 !
 exhau/ cam is fitt$ on side %aft ) a   
fea!r--i4e41 a headless key--& ! cam be+
 capable ( longitud9al movem5t1 su*     
movem5t be+ controll$ by a small lev] or
 h&le1 call$ ! half-compression lev]4   
,illu/ration3 ,,fig4 #dj4  ,illu/ration3
 ,,fig4 #dj;,a4  ,hav+ once ?or\ghly    
grasp$ ! important "p ! cams play 9 !   
work+ ( ! eng9e1 x w be an easy matt] to
 adju/ ! valve sett+s1 & to keep !m     
adju/$ correctly4 ,! effect ( a wrong   
sett+ w !n be /rik+ly app>5t4 ,on small 
eng9es a sep>ate cam to op]ate ! gas    
valve is n a necessity2 & ! practice (  
fitt+ ! gas valve sp9dle 7or ! peck]1 ! 
effect w\ld be ! same7 ) a device =     
increas+ or dim9i%+ its l5g?1 is also   
unnecess>y & uns\nd4  ,! we> on a       
well-design$ gas valve op]at+ me*anism  
is practically nil2 & ev5 if !re 0 we>1 
! effect w\ld be to cause ! valve to op5
 a trifle lat] & close soon] ?an x w\ld 

o!rwise1 i4e41 x w\ld rema9 op5 a %ort] 
"t dur+ ea* *>g+ /roke4 ,?is 9 turn 7o!r
 conditions rema9+ ! same7 w\ld give u a
 weak] mixture2 & al?\gh too weak a     
mixture is pref]able to a too ri* "o1 we
 %\ld h to adopt "s means ( increas+ !  
ri*ness ( ! mixture2 o!rwise ! maximum  
p[] ( ! eng9e w\ld soon be se5 to       
dim9i%4  ,to get ! mixture normal aga9  
we mu/ ei!r enl>ge ! gas inlet or cut   
d[n ! air-supply some:at1 & s keep !    
proportions ! same4 ,t is to say1 !     
quality ( ! mixture is dep5d5t ^u !     
relative dim5sion ( ! gas & air inlets4 
,we "k by actual trial t if at !        
completion ( ! *>g+ /roke ! pressure 9 !
 cyl9d] is approximately t ( !          
atmosph]e1 bett] results are obta9$ ?an 
:5 ! pressure is consid]ably bel[ t ( ! 
atmosph]e4 ,?us1 ! l>g] we make ! inlet 
ports 7b /ill reta9+ correct relative   
dim5sions7 ! m readily w ! mixture be   
drawn into ! cyl9d] z ! pi/on moves     
=w>d1 t5d+ to create a vacuum4 ,( ! two 
c\rses op5 to u to reta9 a good mixture 

x is pref]able to op5 out ! gas-supply1 
= by cutt+ d[n ! air-supply1 & suck+ !  
gas 91 due to ! p>tial vacuum be+ =m$1  
we %\ld be keep+ ! proportions correct  
at ! exp5se ( r$uc+ ! total volume ( !  
explosive mixture 7m /rictly speak+1 !  
d5sity ( ! *>ge7 admitt$ to ! cyl9d]4   
,"u normal conditions x is n necess>y to
 create a high vacuum to suck ! gas into
 ! cyl9d]1 b x is z well to und]/& :at  
results we w\ld t5d to produce1 did we  
"w on ^! l9es4 ,( c\rse1 ) small        
high-spe$ eng9es fitt$ ) suction air    
valve1 ! vacuum is high] ?an x w\ld be 9
 sl[-spe$ eng9es ) me*anically op]at$   
valves4 ,if we take an extreme case z an
 example1 :]e1 to get any gas to speak (
 into ! cyl9d] ! air-supply w\ld h to be
 cut d[n or ?rottl$ to an abnormal      
ext5t1 we w realise at once t su* a     
small quantity ( bo? air & gas w\ld h   
be5 drawn 91 & consequ5tly ! mixture    
w\ld be s r>efi$ t on ! compression     
/roke ! pressure w\ld possibly be       
extremely l[ & totally inadequate to    

produce effici5t work+4 ,moreov]1 work+ 
at su* a high vacuum z ?is w\ld n only  
prev5t u obta9+ a normal explosion 9 !  
cyl9d]1 b w\ld upset ! work+ ( ! exhau/ 
valve4 ,! latt] be+ held d[n on its seat
 dur+ ! suction /roke by means ( a      
spiral spr+ w\ld be lift$ (f its seat by
 suction 7! p>tial vacuum 9 ! cyl9d]71 &
 any burnt gases :i* happ5$ to be hang+ 
ab\t 9 ! exhau/ port or pipe w\ld be    
drawn into ! cyl9d] aga91 & t5d to damp 
! ensu+ explosion4 ,too e>ly clos+ ( !  
exhau/ %\ld be avoid$ almo/ z rigor\sly 
z too late4 ,! latt] w affect ! work+ 9 
a simil> way to ! exhau/ be+ lift$ on ! 
*>g+ /roke by suction2 on ! o!r h&1 if x
 closes too soon1 ! entire volume (     
burnt gases w n h be5 swept out ( !     
cyl9d]1 & ! effect w aga9 be to damp !  
foll[+ explosion4  ,! gas valve op5s j  
aft] ! crank is above ! back c5tre &    
closes j be=e ! front c5tre is rea*$1 t 
is1 op5+ a little aft] ! air valve &    
clos+ a %ade be=e x1 ?us e p>ticle ( gas
 is us$ 9 ! cyl9d]1 due to a draught (  

air be+ drawn 9 aft] ! gas valve has be5
 clos$4  ,! sett+s ( ! valve be+ (      
prim>y importance1 no matt] :at size    
eng9e we are deal+ )1 & be+ also ! mo/  
confus+ matt] = anyone unacqua9t$ ) gas 
eng9es to grasp1 x w n be out ( place to
 sugge/ a simple me?od ( *eck+ ^!       
sett+s4  ,let u beg9 by pull+ ! fly-:eel
 r\nd backw>ds until we feel ! pi/on is 
on ! compression /roke1 !n f ?is po9t--!
 crank be+ ab\t #de deg4 above ! front  
c5tre--pull ! :eel r\nd until ! crank is
 9 ! position = ! exhau/ op5+ 7see fig4 
#bh74 ,9 ?is position !re %\ld be b !   
slighte/ play 9 ! exhau/ lev]1 %[+ t !  
valve is j on po9t ( op5+2 & by keep+   
"o's h& on ! lev] :il/ ! fly-:eel is    
pull$ r\nd v sl[ly 7x is a good plan to 
get "s "o else to d ! pull+ r\nd71 x is 
possible to asc]ta9 ! precise po9t at   
:i* ! valve op5s4 ,next pull r\nd till !
 crank is 9 ! position = ! air valve    
op5+1 & obs]ve t x is set correctly4 ,!n
 g on to a trifle above ! back c5tre1   
:]e ! exhau/ valve %\ld close1 & s on   

till ! op5+ & clos+ ( ea* valve has be5 
*eck$4 ,x w be notic$ t ! air1 &        
sometimes ! gas1 valve op5s be=e !      
exhau/ closes4 ,?is ov]lap is necess>y2 
& x w be f\nd t ! small] ! eng9e & !    
high] ! spe$ ! great] ?is ov]lap w be to
 obta9 good results1 al?\gh a good deal 
( individual judgm5t mu/ be us$ 9 settl+
 ! exact am\nt ( ov]lap1 z ! requisite  
am\nt may1 to get ! be/ results1 v>y 9  
diff]5t eng9es ( precisely ! same       
dim5sions & type4  ,:5 deal+ ) eng9es   
:i* h no sep>ate gas valve--! gas be+   
admitt$ ) ! air1 :i* is sometimes ! case
 ) v small eng9es--! above notes ref]r+ 
to ! gas sett+ indep5d5tly1 w1 ( c\rse1 
n hold good4  ,x may be m5tion$ ) reg>d 
to ! lump on ! op5+ side ( ! exhau/ cam1
 t ?is if ov]done is f\nd to be         
detrim5tal on l>ge eng9es1 & ev5 on     
small ones4 ,if x is too l>ge1 x w cause
 bo? exhau/ valve & seat to become burnt
 & pitt$1 due to ! surface be+ expos$ to
 ! exce$+ly high temp]ature ( ! exp&+   
gases4 ,if x is too l>ge1 x is equival5t

 to op5+ ! exhau/ valve too e>ly1 & !   
effect is ! same1 viz41 a wa/e ( p[] &  
damage to ! valve & its seat4           
,illu/ration3 ,,fig4 #dc4  ,illu/ration3
 ,,fig4 #dd4--;,brake ,te/+4  ,! me?od (
 gr9d+ 9 ! valves to _! seats ) em]y    
p[d] & oil is s well kn[n t no fur!r    
description is ne$$ "h4 ,we give1 h[ev]1
 9 fig4 #dc a sket* %[+ a v exp$iti\s   
way ( deal+ ) v badly worn or burnt     
seats4 ,! sket* expla9s itself4 ,su* a  
tool is readily made2 ev5 ! cutt] c\ld  
be turn$ & fil$ up to %ape & !n h>d5$ at
 home4 ,by lightly tapp+ 9 ! tap] cott] 
p9 little by little1 suffici5t pressure 
is put on ! cutt] to make x an easy     
matt] to completely re-face an old seat 
or =m a new "o4 ,a ,t-wr5* or tommy c be
 us$ to "w ! cutt] sp9dle4 ,! l[] "p ( !
 latt] mu/ be ! same diamet] z ! exi/+  
valve sp9dle2 ! bu% acts z a guide2 & z 
! bevel ( ! cutt] %\ld be ! same z t ( !
 valve1 a v little gr9d+ 9 ) em]y p[d]  
is requir$ to f9i% ! job (f4  ,9 fig4   
#dd we give a diagram %[+ ! me?od ( te/+

 = ,brake ,h4,p4 ( eng9e1 z x is        
frequ5tly int]e/+ to make su* a simple  
te/ aft] any alt]ations or adju/m5ts h  
be5 made4  ,two spr+ balances & a rope  
or cord 7accord+ to ! size ( ! eng9e71  
fitt$ ) a few wood blocks z %[n 9       
section1 fig4 #dd1 to keep ! rope on !  
rim ( fly-:eel1 is all t is requir$ =   
?is te/4 ,! foll[+ =mula may be us$ =   
arriv+ at ! ,b4,h4,p43--    ,b4,h4,p4   
7,s#a - ,s#b7 #c4ad x ,d x ,r _/ #ccjjj 
,s#a  ,read+ 9 lbs4 ( spr+ balance ,no4 
#a4   ,s#b  ,read+ 9 lbs4 ( spr+ balance
 ,no4 #b4   ,d   ,diamet] ( fly-:eel &  
diamet] ( brake        rope 9 feet4   ,r
   ,revolutions ( fly-:eel p] m9ute4    
,z #c4ad x ,d _/ #ccjjj w always rema9 !
 same = any giv5 eng9e &   ge>1 we may  
call t expression ,c2 !n ! ,b4,h4,p4 may
 be writt5--    ,b4,h4,p4  7,s#a - ,s#b7
 ,c ,r     ,,*apt] ,,viii  ,,oil        
,,eng9es   ,! small oil eng9e is        
practically ! same z ! gas eng9e1 ) !   
addition ( a vaporis] = conv]t+ ! oil   
into gas1 or vap\r1 to be explod$ 9 !   

cyl9d]2 consequ5tly ! "o may be conv]t$ 
into ! o!r 9 _m cases )\t mu* tr\ble4 ,!
 difficulty ( produc+ an effici5t oil   
eng9e lies pr9cipally 9 devis+ a        
satisfactory & reliable vap\ris]--"o :i*
 w "w equally well "u all loads4 ,! heat
 suppli$ to ! *amb] mu/ be suffici5t to 
vaporise ! oil1 b n great en\gh to      
decompose x4 ,!re are v>i\s me?ods (    
vaporis+ ! oil1 & _m types ( vaporis]s  
are employ$ to atta9 ! same end4 ,!re   
are "s 9 :i* a *>ge ( oil is drawn by   
suction into a hot *amb] 9 :i* x is     
conv]t$ into vap\r & at ! same "t mix$ )
 a small quantity ( hot air2 ?is ri*    
mixture is !n pass$ into ! combu/ion    
*amb] ( ! eng9e1 9 ! same mann] z       
coal-gas w\ld be1 :]e x is fur!r dilut$ 
) m air drawn 9 ?r\gh ! air valve4 ,o!r 
arrangem5ts cause a jet ( oil to be     
inject$ into a *amb] conta9+ hot air1 9 
! =m ( spray1 :i* imm$iately conv]ts !  
oil into vap\r1 & is !n pass$ into !    
cyl9d]1 compress$1 & fir$4 ,!n1 aga91 we
 c pump oil ?r\gh a spray+ nipple into !

 vap\ris] 7:i* is kept at a suitable    
temp]ature7 :il/ ! cyl9d] is be+ fill$ )
 air on ! suction /roke4 ,on ! foll[+   
compression /roke ! air is driv5 into ! 
vap\ris]1 :i* communicates ) ! cyl9d]   
?r\gh a n>r[ neck1 & mixes intimately ) 
! oil vap\r4 ,gradually1 z ! pressure   
rises1 due to compression1 ! *>ge       
becomes m & m explosive1 until at !     
completion ( ?is /roke x has atta9$ !   
prop] proportions ( air & oil vap\r1 &  
is fir$ by ! temp]ature ( ! vap\ris] & t
 caus$ by a high compression2 t is1 !   
*>ge is fir$ automatically2 & once !    
eng9e is runn+1 no heat+ lamp is requir$
 to keep ! vap\ris] at ! correct        
temp]ature4 ,x is necess>y1 h[ev]1 to   
raise x to ! workable temp]ature at     
/>t+4 ,?is is kn[n z ! ,hornsby-,akroyd 
me?od4  ,capel's arrangem5t is also     
simple & effici5t1 & has ! additional   
advantage ( be+ capable ( be+ fitt$ to  
_! exi/+ gas eng9es1 ! conv]sion be+    
made 9 a v %ort "t4 ,?is vap\ris]       
consi/s prim>ily ( a tubul> ca/+ ,a1 on 

! outside ( :i* are =m$ a s]ies (       
v]tical ribs1 %[n 9 plan1 fig4 #df1     
runn+ to )9 a %ort di/ance ( ! flange at
 "o end1 z %[n 9 ! section1 fig4 #de1   
?us provid+ an annul> space ,c betwe5 ! 
upp] ends ( ! ribs & ! flange4 ,?is ca/+
 is enclos$ by an out] cas+ ,b1 :i* fits
 well ov] ! inn] tube4 ,x has also a    
numb] ( small holes drill$ ne> ! l[] end
 communicat+ ) ! *annels betwe5 ! ribs4 
,?us x w be se5 t :5 ! gas valve is op5$
 & suction takes place1 air is drawn 9  
?r\gh ^! holes1 passes up into ! annul> 
space ,c bel[ ! top flange1 f !re       
travels to ! opposite side ( vap\ris]1 &
 mixes ) ! oil :i* is also be+ drawn 9  
?r\gh a small nipp] at ,n1 fig4 #de4    
,bo? !n pass betwe5 a s]ies ( pegs1 :]e 
!y become ?or\ghly mix$1 & f9ally pass  
on to ! inlet valve ,v1 fig4 #dg1 & s   
into ! cyl9d]1 :]e ! complete *>ge is   
mix$ up & compress$ & fir$ 9 ! usual    
mann]4 ,iron ignition tubes may be us$1 
& "o heat+ lamp s]ves a d\ble purpose 9 
keep+ ! tube & vap\ris] hot at ! same   

"t4 ,?is lamp is f$ by means ( a pump   
actuat$ f ! side %aft4 ,! plung] ( !    
pump is load$ ) a spiral spr+1 :i* may  
be adju/$ to give any desir$ pressure1 &
 is kept con/ant & /eady by means ( an  
air vessel4 ,?is pump is %[n 9 fig4 #dh4
 ,x is actuat$ by means ( a rod & lev] f
 ! side %aft ( eng9e4 ,! plung] ,p works
 9 a b>rel ,b1 :i* is c>ri$ by a small  
res]voir ,r1 ! latt] be+ 9 communication
 ) ! ma9 oil tank by means ( ! pipe ,h4 
,illu/ration3 ,,fig4 #df4  ,illu/ration3
 ,,fig4 #de4  ,illu/ration3 ,,fig4 #dg4 
,illu/ration3 ,,fig4 #dh4  ,illu/ration3
 ,,fig4 #di4  ,illu/ration3 ,,fig4 #ej4 
,illu/ration3 ,,fig4 #ea4  ,! plung] is 
load$ ) a spiral spr+1 & has a ball     
valve1 z %[n4 ,int]m$iate betwe5 ?is    
small res]voir & ! ma9 oil tank is ano!r
 set ( valves1 %[n 9 fig4 #di4 ,x w be  
se5 t ! suction ( ! pump w draw ! oil   
up1 ! small & l[] ball valve1 ( c\rse1  
all[+ x to pass freely4 ,on ! d[n /roke 
! l[] valve w be automatically clos$1 & 
! oil w be put "u pressure1 ?is be+     

det]m9$ by ! load on ! plung] valve1 :i*
 is adju/able by means ( ! screw ,s1    
fig4 #dh4 ,:5 ! requir$ pressure 9 !    
pipe ,p1 figs4 #de & #di1 has be5       
atta9$1 ! plung] valve lifts on ea*     
/roke & ! surplus oil fl[s ?r\gh !      
plung] into ! small res]voir ,r4 ,!     
latt] is at ab\t ! same level z ano!r   
/ill small] res]voir ,m 7%[n 9 figs4 #dg
 & #ej71 a fl[ ( oil be+ e/abli%$ betwe5
 ! two by means ( a pipe ,q 7see figs4  
#dh & #ej74 ,9 ! res]voir ,r is fitt$ an
 ov]fl[ pipe1 s t ! oil _c rise beyond a
 c]ta9 level2 h5ce ! head ( oil 9 !     
small] "o ,m is always con/ant4 ,on !   
suction /roke a p>tial vacuum is =m$ 9 !
 eng9e cyl9d]1 consequ5tly ! pressure 9 
! vap\ris] drops some:at bel[ t ( !     
atmosph]e1 & ?is small diff]5ce 9       
pressure is en\gh to cause ! oil to rise
 9 ! small passage ,x1 fig4 #de1 beyond 
its normal level1 & ov]fl[ into !       
vap\ris+ *amb]1 z previ\sly describ$4 ,!
 valve or nipp] ,n is %[n op5 9 !       
diagram1 fig4 #de1 & all t is requir$ to

 /op ! eng9e :5 runn+ is to drop ! small
 h&le ,l1 fig4 #de1 :5 ! valve w close1 
due to ! spr+ ,s4 ,! air vessel %[n 9   
fig4 #di is 9 communication ) ! pipe    
lead+ to ! bl[ lamp4 ,a pressure gauge c
 also be fitt$1 al?\gh x is n 9 any way 
a necessity4  ,! rat*et :eel & pawl %[n 
9 fig4 #dh are "p ( ! lubricator4 ,!    
:eel drives a brass or gun-metal plug1  
produc+ an int]mitt5t rot>y motion4 ,!  
plug has a small hole 9 its p]iph]y1 :i*
 becomes fill$ ) oil :5 x is at ! upp]  
"p ( its travel1 & empties ! oil out    
into a dis*>ge pipe ,t1 :5 x is inv]t$1 
& is !n l$ away & appli$ to ! pi/on at !
 requir$ spot4 ,fig4 #ea %[s ?is        
arrangem5t 9 section4