,illu/ration3 ,,! ,,mo/ ,,important ,,tool ,,9 ,,! ,,build+ ,,( ,,model ,,a]oplanes4 ,illu/ration by p]mission f ,,messrs4 ,a4 ,,gall5kamp ,,co',s4 ,,*emical ,,catalogue4 ,,! ,,!ory ,,& ,,practice ,,( ,,model ,,a]oplan+ ,,by ,v4,e4 ,,johnson1 ,m4,a4 ,,au?or ,,( ',,! ,,be/ ,,%ape ,,= ,,an ,,air%ip1' ',,so>+ ,,flight1' ',,h[ ,,to ,,advance ,,! ,,sci5ce ,,( ,,a]onautics1' ',,h[ ,,to ,,build ,a ,,model ,,a]oplane1' ,,etc4 ,model ,a]oplan+ is an ,art 9 itself ,illu/ration ,london ,e4 ,f4,n4 ,,spon1 ,,ltd41 #eg ,,haym>ket ,new ,york ,,spon ,,*amb]la91 #abc ,,lib]ty ,,/reet #aiaj ,,preface ,! object ( ?is little book is n to describe h[ to con/ruct "s p>ticul> k9d ( a]oplane2 ?is has be5 done else:]e3 b to n>rate 9 pla9 language ! g5]al practice & pr9ciples ( model a]oplan+4 ,!re is a sci5ce ( model a]oplan+--j z !re is a sci5ce ( model ya*t+ & model /eam & electric traction1 & an endeav\r is made 9 ! foll[+ pages to d 9 "s measure = model a]oplanes :at has already be5 done = model ya*ts & locomotives4 ,to a*ieve ! be/ results1 !ory & practice mu/ g h& 9 h&4 ,f a s]ies ( c>efully conduct$ exp]im5ts empirical =mul c be obta9$ :i*1 comb9$ lat] ) ma!matical induction & d$uction1 may lead1 n only to a m accurate & g5]aliz$ law ?an t conta9$ 9 ! empirical =mula1 b to valuable d$uctions ( a totally new type1 embody+ "s g5]al law hi!rto q unkn[n by exp]im5tali/s1 :i* 9 its turn may s]ve z a f\ndation or /epp+ /one = sugge/+ o!r exp]im5ts & empirical =mul :i* may be ( especial importance1 to be treat$ 9 _! turn l _! pr$ecessor4 ,by especial importance1 ,i mean n only to model1 b ,a]oplan+ g5]ally4 ,z to ! value ( exp]im5ts on or ) models ) respect to full-siz$ ma*9es1 fifte5 ye>s ago ,i held ! op9ion t !y 7 a v d\btful factor4 ,i h s9ce consid]ably modifi$ t view1 & n[ consid] t exp]im5ts ) models--if prop]ly c>ri$ out1 & giv5 due1 n undue1 weight--bo? c & w be ( z mu* use to ! sci5ce ( ,a]onautics z !y h already prov$ !mselves to be 9 t ( m>9e eng9e]+4 ,! subject ( model propell]s & motors has be5 some:at fully dealt )1 z b little has be5 publi%$ 79 book =m1 at any rate7 on ^! all-important dep>tm5ts4 ,on simil> gr\nds ! reasons :y & h[ a model a]oplane flies h be5 practically omitt$1 because ^! h be5 dealt ) m or less 9 e book on heavi]-?an-air ma*9es4 ,great c>e has be5 ex]cis$ 9 ! selection ( matt]1 & 9 ! v>i\s facts /at$ h]e92 9 mo/ cases ,i h p]sonally v]ifi$ !m2 great pa9s h also be5 ex]cis$ to exclude n only mislead+1 b also d\btful matt]4 ,i h no p]sonal axe to gr9d :atev]1 nor am ,i connect$ ei!r directly or indirectly ) any firm ( a]oplane build]s1 model or o!rwise4 ,! /atem5ts conta9$ 9 ^! pages are absolutely free f bias ( any k9d1 & = !m ,i am prep>$ to accept full responsibility4 ,i h to ?ank ,messrs4 ,a4,w4 ,,gamage 7,holborn7 = ! use ( v>i\s model p>ts = te/+ purposes1 & also = ! use ( v>i\s electros f _! mod]n ,aviation ,catalogue2 also ,messrs4 ,t4,w4,k4 ,,cl>ke ,,co41 ( ,k+/on-on-,?ames4 ,= ! fur!r use ( electros1 & = p]mission to reproduce illu/rations :i* h previ\sly appe>$ 9 _! pap]s1 ,i mu/ express my ackn[l$gm5t & ?anks to ! publi%]s ( ! ,model ,eng9e]1 ,flight1 & ! ,a]o4 ,corrections & sugge/ions ( any k9d w be gratefully receiv$1 & duly ackn[l$g$4 ,v4,e4 ,,johnson4 ,,cont5ts ,,introduction4 ,,page #a-e4 ,! two classes ( models--,fir/ requisite ( a model a]oplane4 #f4 ,an art 9 itself4 #g4 ,! lead+ pr9ciple #a ,,*apt] ,i4 ,,! ,,"q ,,( ,,weight4 #a-b4 ,its prim>y importance bo? 9 rubb] & p[]-driv5 models--,pr(essor ,langley's exp]i5ces4 #c4 ,!oretical aspect ( ! "q4 #d4 ,means :]eby m weight c be c>ri$--,h[ to obta9 maximum /r5g? ) m9imum weight4 #e4 ,heavy models v]sus light ones #d ,,*apt] ,,ii4 ,,! ,,"q ,,( ,,resi/ance4 #a4 ,! *ief function ( a model 9 ! m$ium 9 :i* x travels4 #b4 ,resi/ance consid]$ z load p]c5tage4 #c4 ,h[ made up4 #d4 ,! %ape ( m9imum resi/ance4 #e4 ,! case ( rubb]-driv5 models4 #f4 ,! a](oil surface--,%ape & mat]ial z affect+ ?is "q4 #g4 ,sk9 friction--,its coeffici5t4 #h4 ,exp]im5tal pro(s ( its exi/5ce & importance #g ,,*apt] ,,iii4 ,,! ,,"q ,,( ,,balance4 #a4 automatic /ability ess5tial 9 a fly+ model4 #b4 !oretical rese>*es on ?is "q4 #c-f4 a brief summ>y ( ! *ief conclusions arriv$ at--rem>ks on & d$uctions f ! same--conditions = automatic /ability4 #g4 !ory & practice--/r+fell[--pnaud--tat9--! "q ( f9s--cl>ke's models--"s fur!r consid]ations4 #h4 longitud9al /ability4 #i4 transv]se /ability4 #aj4 ! dih$ral angle4 #aa4 diff]5t =ms ( ! latt]4 #ab4 ! upturn$ tip4 #ac4 ! mo/ effici5t section #ac ,,*apt] ,,iv4 ,,! ,,motive ,,p[]4 ,,section ,i4--,,rubb] ,,motors4 #a4 ,"s exp]im5ts ) rubb] cord4 #b4 ,its ext5sion "u v>i\s weights4 #c4 ,! laws ( elongation 7/ret*+7--,p]man5t set4 #d4 ,effects ( elongation on its volume4 #e4 ,/ret*$-twi/$ rubb] cord--,torque exp]im5ts ) rubb] /r&s ( v>y+ l5g? & numb]4 #f4 ,results plott$ z graphs--,d$uctions--,v>i\s relations--,h[ to obta9 ! mo/ effici5t results--,relations betwe5 ! torque & ! numb] ( /r&s1 & betwe5 ! l5g? ( ! /r&s & _! numb]4 #g4 ,analogy betwe5 rubb] & spr+ motors--,:]e x fails to hold4 #h4 ,"s fur!r practical d$uctions4 #i4 ,! numb] ( revolutions t c be giv5 to rubb] motors4 #aj4 ,! maximum numb] ( turns4 #aa4 ,lubricants = rubb]4 #ab4 ,action ( copp] ^u rubb]4 #ab;,a4 ,action ( wat]1 etc4 #ab;,b4 ,h[ to pres]ve rubb]4 #ac4 ,to te/ rubb]4 #ad4 ,! %ape ( ! section4 #ae4 ,size ( section4 #af4 ,ge>$ rubb] motors4 #ag4 ,! only sy/em wor? consid]ation--,its practical difficulties4 #ah4 ,its advantages #bd ,,section ,,ii4--,,o!r ,,=ms ,,( ,,motors4 #ah;,a4 ,spr+ motors2 _! inf]iority to rubb]4 #ah;,b4 ,! mo/ effici5t =m ( spr+ motor4 #ah;,c4 ,compress$ air motors--,a fasc9at+ =m ( motor1 on pap]4 #ah;,d4 ,! pneumatic drill--,application to a model a]oplane--,l5g? ( possible flight4 #ah;,e4 ,! pressure 9 motor-c> tyres4 #ai4 ,h>graves' compress$ air models--,! be/ results comp>$ ) rubb] motors4 #bj4 ,! effect ( heat+ ! air 9 its passage f ! res]voir to ! motor--,! great ga9 9 effici5cy !reby atta9$--,liquid air--,practical drawbacks to ! compress$-air motor4 #ba4 ,r$uc+ valves--,l[e/ work+ pressure4 #bb4 ,! inf]iority ( ?is motor comp>$ ) ! /eam eng9e4 #bb;,a4 ,tat9's air-compress$ motor4 #bc4 ,/eam eng9e--,/eam eng9e model--,pr(essor ,langley's models--,8 exp]im5t ) v>i\s =ms ( motive p[]--,conclusions arriv$ at4 #bd4 ,8 /eam eng9e models--,difficulties & failures--& f9al success--,! boil] ! great difficulty--,8 model describ$4 #be4 ,! use ( _s or "s v volatile hydroc>bon 9 ! place ( wat]4 #bf4 ,/eam turb9es4 #bg4 ,relation betwe5 difficulty 9 con/ruction & ! size ( ! model4 #bh4 ,exp]im5ts 9 ,france4 #bi4 ,petrol motors4--,b few successful models4 #cj4 ,limit to size4 #ca4 ,/ang]'s successful model describ$ & illu/rat$4 #cb4 ,"o-cyl9d] petrol motors4 #cc4 ,electric motors #ci ,,*apt] ,v4 ,,propell]s ,,or ,,screws4 #a4 ,! position ( ! propell]4 #b4 ,! numb] ( blades4 #c4 ,fan v]sus propell]4 #d4 ,! function ( a propell]4 #e4 ,! pit*4 #f4 ,slip4 #g4 ,?ru/4 #h4 ,pit* coeffici5t 7or ratio74 #i4 ,diamet]4 #aj4 ,!oretical pit*4 #aa4 ,uni=m pit*4 #ab4 ,h[ to asc]ta9 ! pit* ( a propell]4 #ac4 ,holl[-fac$ blades4 #ad4 ,blade area4 #ae4 ,rate ( rotation4 #af4 ,%r\d+4 #ag4 ,g5]al design4 #ah4 ,! %ape ( ! blades4 #ai4 ,_! g5]al cont\r--,propell] design--,h[ to design a propell]4 #bj4 ,exp]im5ts ) propell]s--,havill&'s design = exp]im5ts--,! au?or exp]im5ts on dynamic ?ru/ & model propell]s g5]ally4 #ba4 ,fabric-cov]$ screws4 #bb4 ,exp]im5ts ) tw9 propell]s4 #bc4 ,! ,flem+ ,williams propell]4 #bd4 ,built-up v4 twi/$ wood5 propell]s #eb ,,*apt] ,,vi4 ,,! ,,"q ,,( ,,su/5tation4 ,,! ,,c5tre ,,( ,,pressure4 #a4 ,! c5tre ( pressure--,automatic /ability4 #b4 ,oscillations4 #c4 ,ar*$ surfaces & movem5ts ( ! c5tre ( pressure--,rev]sal4 #d4 ,! c5tre ( gravity & ! c5tre ( pressure4 #e4 ,camb]4 #f4 ,dipp+ front edge--,camb]--,! angle ( incid5ce & camb]--,attitude ( ! ,wright ma*9e4 #g4 ,! mo/ effici5t =m ( camb]4 #h4 ,! in/ability ( a deeply camb]$ surface4 #i4 ,aspect ratio4 #aj4 ,con/ant or v>y+ camb]4 #aa4 ,c5tre ( pressure on ar*$ surfaces #gh ,,*apt] ,,vii4 ,,mat]ials ,,= ,,a]oplane ,,con/ruction4 #a4 ,! *oice /rictly limit$4 #b4 ,bamboo4 #c4 ,a%--spruce-- :itewood--popl>4 #d4 ,/eel4 #e4 ,umbrella section /eel4 #f4 ,/eel wire4 #g4 ,silk4 #h4 ,alum9ium & magnalium4 #i4 ,alloys4 #aj4 ,%eet ebonite--,vulcaniz$ fibre--,%eet celluloid--,mica #hf ,,*apt] ,,viii4 ,,h9ts ,,on ,,! ,,build+ ,,( ,,model ,,a]oplanes4 #a4 ,! *ief difficulty to ov]come4 #b4 ,g5]al design--,! pr9ciple ( cont9uity4 #c4 ,simple monoplane4 #d4 ,importance ( sold]+4 #e4 ,?+s to avoid4 #f4 ,a](oil ( metal--wood--or fabric4 #g4 ,%ape ( a](oil4 #h4 ,h[ to camb] an a]ocurve )\t ribs4 #i4 ,flexible jo9ts4 #aj4 ,s+le surfaces4 #aa4 ,! rod or tube c>ry+ ! rubb] motor4 #ab4 ,position ( ! rubb]4 #ac4 ,! position ( ! c5tre ( pressure4 #ad4 ,elevators & tails4 #ae4 ,skids v]sus :eels--,mat]ials = skids4 #af4 ,%ock absorb]s1 h[ to atta*--,relation betwe5 ! gap & ! *ord #ic ,,*apt] ,,ix4 ,,! ,,/e]+ ,,( ,,! ,,model4 #a4 ,a problem ( great difficulty--,effects ( propell] torque4 #b4 ,h[ obviat$4 #c4 ,! two-propell] solution--,! reason :y x is only a p>tial success4 #d4 ,! spe$ solution4 #e4 ,v]tical f9s4 #f4 ,balanc+ tips or ail]ons4 #g4 ,weight+4 #h4 ,by means ( transv]sely cant+ ! elevator4 #i4 ,! necessity = "s =m ( keel #aje ,,*apt] ,x4 ,,! ,,laun*+ ,,( ,,! ,,model4 #a4 ,! direction 9 :i* to laun* !m4 #b4 ,! velocity--wood5 a](oils & fabric-cov]$ a](oils--,poynt]'s laun*+ app>atus4 #c4 ,! laun*+ ( v light models4 #d4 ,l>ge size & p[]-driv5 models4 #e4 ,models design$ to rise f ! gr\nd--,paulhan's prize model4 #f4 ,! sett+ ( ! elevator4 #g4 ,! mo/ suitable propell] = ?is =m ( model4 #h4 ,pr(essor ,kress' me?od ( laun*+4 #i4 ,h[ to laun* a tw9 screw model4 #aj4 ,a prior revolution ( ! propell]s4 #aa4 ,! be/ angle at :i* to laun* a model #aji ,,*apt] ,,xi4 ,,helicopt] ,,models4 #a4 ,models q easy to make4 #b4 ,sir ,george ,cayley's helicopt] model4 #c4 ,phillips' successful p[]-driv5 model4 #d4 ,toy helicopt]s4 #e4 ,incorrect & correct way ( arrang+ ! propell]s4 #f4 ,fabric cov]$ screws4 #g4 ,a design to obviate weight4 #h4 ,! "q ( a f9 or keel4 #aac ,,*apt] ,,xii4 ,,exp]im5tal ,,records #aaf ,,*apt] ,,xiii4 ,,model ,,fly+ ,,competitions4 #a4 ,a few g5]al details conc]n+ su*4 #b4 ,a]o ,models ,association's classification1 etc4 #c4 ,v>i\s po9ts to be kept 9 m9d :5 compet+ #aai ,,*apt] ,,xiv4 ,,useful ,,notes1 ,,tables1 ,,=mul1 ,,etc4 #a4 ,comp>ative velocities4 #b4 ,conv]sions4 #c4 ,areas ( v>i\s %ap$ surfaces4 #d4 ,fr5* & ,engli% measures4 #e4 ,useful data4 #f4 ,table ( equival5t incl9ations4 #g4 ,table ( sk9 friction4 #h4 ,table ,i4 7metals74 #i4 ,table ,,ii4 7w9d pressures74 #aj4 ,w9d pressure on v>i\s %ap$ bodies4 #aa4 ,table ,,iii4 7lift & drift7 on a camb]$ surface4 #ab4 ,table ,,iv4 7lift & drift7--,on a plane a](oil--,d$uctions4 #ac4 ,table ,v4 7timb]74 #ad4 ,=mula connect+ weight lift$ & velocity4 #ae4 ,=mula connect+ models ( simil> design b diff]5t weights4 #af4 ,=mula connect+ p[] & spe$4 #ag4 ,propell] ?ru/4 #ah4 ,to det]m9e exp]im5tally ! /atic ?ru/ ( a propell]4 #ai4 ,horse-p[] & ! numb] ( revolutions4 #bj4 ,to comp>e "o model ) ano!r4 #ba4 ,"w done by a clockwork spr+ motor4 #bb4 ,to asc]ta9 ! horse-p[] ( a rubb] motor4 #bc4 ,foot-p\nds ( en]gy 9 a giv5 weight ( rubb]--,exp]im5tal det]m9ation (4 #bd4 ,!oretical l5g? ( flight4 #be4 ,to te/ diff]5t motors4 #bf4 ,effici5cy ( a model4 #bg4 ,effici5cy ( design4 #bh4 ,naph?a eng9es4 #bi4 ,horse-p[] & weight ( model petrol motors4 #cj4 ,=mula = rat+ ! same4 #cj;,a4 ,relation betwe5 /atic ?ru/ ( propell] & total weight ( model4 #ca4 ,h[ to f9d ! height ( an inaccessible object 7kite1 balloon1 etc474 #cb4 ,=mula = ,i4,h4,p4 ( model /eam eng9es #abe ,,app5dix ,a4 ,"s models :i* h won m$als at op5 competitions #adc ,,gloss>y ,,( ,,t]ms ,,us$ ,,9 ,,model ,,a]oplan+4 ,a]oplane4 ,a motor-driv5 fly+ ma*9e :i* relies ^u surfaces = its support 9 ! air4 ,monoplane 7s+le74 ,an a]oplane ) "o pair ( out/ret*$ w+s4 ,a](oil4 ,^! out/ret*$ w+s are (t5 call$ a](oil surfaces4 ,"o pair ( w+s =m+ "o a](oil surface4 ,monoplane 7d\ble74 ,an a]oplane ) two a](oils1 "o beh9d ! o!r or two ma9 planes1 t&em-wise4 ,biplane4 ,an a]oplane ) two a](oils1 "o bel[ ! o!r1 or hav+ two ma9 planes sup]pos$4 ,triplane4 ,an a]oplane hav+ ?ree su* a](oils or ?ree su* ma9 planes4 ,multiplane4 ,any su* ma*9e hav+ m ?an ?ree ( ! above4 ,glid]4 ,a motorless a]oplane4 ,helicopt]4 ,a fly+ ma*9e 9 :i* propell]s are employ$ to raise ! ma*9e 9 ! air by _! own unaid$ ef=ts4 ,dih$ral ,angle4 ,a dih$ral angle is an angle made by two surfaces t d n lie 9 ! same plane1 i4e4 :5 ! a](oils are arrang$ ,v-%ap$4 ,x is bett]1 h[ev]1 to some:at ext5d ?is def9ition1 & n to consid] x z necess>y t ! two surfaces d actually meet1 b w\ld d s if produc$ ?us 9 figure4 ,,ba & ,,cd are /ill dih$rals1 sometimes t]m$ upturn$ tips4 ,illu/ration3 ,dih$rals4 ,span is ! di/ance f tip to tip ( ! ma9 support+ surface measur$ transv]sely 7across7 ! l9e ( flight4 ,camb] 7a slight ar*+ or convexity upw>ds74 ,?is t]m d5otes t ! a](oil has su* a curv$ transv]se section4 ,*ord is ! di/ance betwe5 ! ent]+ 7or lead+7 edge ( ! ma9 support+ surface 7a](oil7 & ! trail+ edge ( ! same2 also def9$ z ! =e & aft dim5sion ( ! ma9 planes measur$ 9 a /raight l9e betwe5 ! lead+ & trail+ edges4 span ,aspect ,ratio is ----- *ord ,gap is ! v]tical di/ance betwe5 "o a](oil & ! "o :i* is imm$iately above x4 7,! gap is usually made equal to ! *ord74 ,angle ( ,incid5ce4 ,! angle ( incid5ce is ! angle made by ! *ord ) ! l9e ( flight4 ,illu/ration3 ,,ab *ord4 ,,ab camb]$ surface4 ,,sp l9e ( flight4 ,,asp alpha ,l ( incid5ce4 ,wid?4 ,! wid? ( an a](oil is ! di/ance f ! front to ! re> edge1 all[+ = camb]4 ,l5g?4 ,?is t]m is usually appli$ to ! ma*9e z a :ole1 f ! front lead+ edge ( elevator 7or supports7 to tip ( tail4 ,ar*$4 ,?is t]m is usually appli$ to a](oil surfaces :i* dip d[nw>ds l ! w+s ( a bird4 ,! curve 9 ?is case be+ at "r angles to camb]4 ,a surface c1 ( c\rse1 be bo? camb]$ & ar*$4 ,propell]4 ,a device = propell+ or pu%+ an a]oplane =w>d or = rais+ x v]tically 7lift+ screw74 ,tractor ,screw4 ,a device = pull+ ! ma*9e 7us$ :5 ! propell] is plac$ 9 ! front ( ! ma*9e74 ,keel4 ,a v]tical plane or planes 7usually t]m$ f9s7 arrang$ longitud9ally = ! purposes ( /ability & /e]+4 ,tail4 ,! plane1 or gr\p ( planes1 at ! re> end ( an a]oplane = ! purpose *iefly ( giv+ longitud9al /ability4 ,9 su* cases ! tail is normally 7approx47 horizontal1 b n unfrequ5tly v]tical tail-pieces are fitt$ z well = /e]+ 7transv]sely7 to ! "r or left1 or ! entire tail may be twi/$ = ! purpose ( transv]se /ability 7vide ,elevator74 ,su* app5dages are be+ us$ less & less ) ! idea ( giv+ actual support4 ,rudd] is ! t]m us$ = ! v]tical plane1 or planes1 :i* are us$ to /e] ! a]oplane sideways4 ,w>p+4 ,! flex+ or b5d+ ( an a](oil out ( its normal %ape4 ,! re> edges ne> ! tips ( ! a](oil be+ dipp$ or tilt$ respectively1 9 ord] to create a tempor>y diff]5ce 9 _! incl9ations to ! l9e ( flight4 ,p]=m$ 9 conjunction ) rudd] movem5ts1 to c\nt]act ! excessive action ( ! latt]4 ,ail]ons 7also call$ right+-tips1 balanc+-planes1 etc474 ,small a]oplanes 9 ! vic9ity ( ! tips ( ! ma9 a](oil = ! purpose ( assi/+ 9 ! ma9t5ance ( equilibrium or = /e]+ purposes ei!r ) or )\t ! assi/ance ( ! rudd]4 ,elevator4 ,! plane1 or planes1 9 front ( ! ma9 a](oil us$ = ! purpose ( keep+ ! a]oplane on an ev5 keel1 or :i* cause 7by be+ tilt$ or dipp$7 ! a]oplane to rise or fall 7vide ,tail74 ,,model ,,a]oplan+ ,,introduction4 #a4 ,model ,a]oplanes are prim>ily divid$ into two classes3 fir/1 models int5d$ be=e all else to be ones t %all fly2 secondly1 models1 us+ ! ^w 9 its prop] s5se ( full-siz$ ma*9es4 ,h]e9 model a]oplanes diff] f model ya*ts & model locomotives4 ,an extremely small model locomotive built to scale w /ill "w1 j z a v small ya*t built to scale w sail2 b :5 y try to build a scale model ( an ,anto9ette monoplane1 includ+ eng9e1 x _c be made to fly unless ! scale be a v l>ge "o4 ,if1 = in/ance1 y endeav\r$ to make a #a_/aj scale model1 y\r model petrol motor w\ld be compell$ to h eight cyl9d]s1 ea* #jeb bore1 & y\r magneto ( su* size z easily to pass ?r\gh a r+ half an in* 9 diamet]4 ,su* a model c\ld n possibly "w4#a ,note4--,read]s w f9d 9 ! ,model ,eng9e] ( ,june #af1 #aiaj1 "s really v f9e work+ draw+s ( a prize-w9n+ ,anto9ette monoplane model4 #b4 ,aga91 al?\gh ! motor con/itutes ! *ief1 x is by no means ! sole difficulty 9 scale model a]oplane build+4 ,to reproduce to scale at scale weight1 or inde$ any?+ approa*+ x1 all ! necess>y--9 ! case ( a full-siz$ ma*9e--framework is n possible 9 a less ?an #a_/e scale4 #c4 ,special difficulties occur 9 ! case ( any prototype tak54 ,= in/ance1 9 ! case ( model ,blriots x is extremely difficult to get ! c5tre ( gravity suffici5tly =w>d4 #d4 ,scale models ( actual fly+ ma*9es t w fly mean models at lea/ #aj or #ab feet across1 & e o!r dim5sion 9 l proportion2 & x mu/ always be c>efully borne 9 m9d t ! small] ! scale ! great] ! difficulties1 b n 9 ! same proportion--x w\ld n be twice z difficult to build a -94 scale model z a -941 b f\r1 five or six times z difficult4 #e4 ,n[1 ! fir/ requirem5t ( a model a]oplane1 or fly+ ma*9e1 is t x %all ,,fly4 ,z w be se5 lat] on--unless ! ma*9e be ( l>ge size1 #aj feet & m spread--! only motor at our disposal is ! motor ( twi/$ rubb] /r&s1 & ?is to be effici5t requires to be long1 & is ( practically uni=m weight ?r\gh\t2 ?is alone alt]s ! entire di/ribution ( weight on ! ma*9e & makes3 #f4 ,model ,a]oplan+ an ,art 9 itself1 & z su* we propose to consid] x 9 ! foll[+ pages4 ,we h said t ! fir/ requisite ( a model a]oplane is t x %all fly1 b !re is no necessity1 nor is x inde$ always to be desir$1 t ?is %\ld be its only "o1 unless x be built ) ! express purpose ( obta9+ a record l5g? ( flight4 ,= ord9>y flights & sci5tific /udy :at is requir$ is a ma*9e 9 :i* m9ute detail is ( second>y importance1 b :i* does along its ma9 l9es approximate to ! real ?+4 #g4 ,simplicity %\ld be ! fir/ ?+ aim$ at--simplicity means effici5cy1 x means x 9 full-siz$ ma*9es1 /ill m does x mean x 9 models--& ?is v "q ( simplicity br+s u to t mo/ important "q ( all1 namely1 ! "q ( weight4 ,,footnote3 #a ,! smalle/ work+ /eam eng9e t ! writ] has ev] he>d ( has a net weight ( #d gra9s4 ,"o hundr$ su* eng9es w\ld be requir$ to weigh "o ounce4 ,! bore be+ #jjc 941 & /roke #a_/cb ( an in*1 r4p4m4 #fjjj p] m941 h4p4 develop$ #a_/dhijjj 7,model ,eng9e]1 ,july #g1 #aiaj74 ,:5 work+ x hums l a bee4 ,,*apt] ,i4 ,,! ,,"q ,,( ,,weight4 #a4 ,! foll[+ is an extract f a lett] t appe>$ 9 ! correspond5ce columns ( ,! ,a]o4#b ,to give y "s idea h[ slight a ?+ w make a model behave badly1 ,i fitt$ a skid to protect ! propell] und]nea? ! a]oplane1 & ! result 9 ret>d+ flight c\ld be se5 v quickly1 al?\gh ! weight ( ! skid 0 almo/ nil4#c ,to all model mak]s :o wi% to make a success ,i w\ld say1 /rip all t useless & heavy *assis (f1 cut d[n ! 'good1 hone/ /ick' t y h = a backbone to half its ?ickness1 /ay x ) wire if x b5ds "u ! /ra9 ( ! rubb]1 put light silk on ! planes1 & use an alum9ium#d propell]4 ,! result w surpass all expectations4 #b4 ,! above ref]s1 ( c\rse1 to a rubb]-motor driv5 model4 ,let u turn to a /eam-driv5 prototype4 ,i take ! be/ kn[n example ( all1 ,pr(essor ,langley's fam\s model4 ,"h is :at ! pr(essor has to say on ! "q#e3-- ,e bit ( ! ma*9]y _h to be con/ruct$ ) sci5tific accuracy4 ,x _h to be te/$ aga9 & aga94 ,! difficulty ( gett+ ! ma*9e light en\gh 0 su* t e "p ( x _h to be remade sev]al times4 ,x w\ld be 9 full work+ ord] :5 some?+ w\ld give way1 & ?is "p w\ld h to be /r5g!n$4 ,?is caus$ additional weight1 & necessitat$ cutt+ (f s mu* weight f "s o!r "p ( ! ma*9]y4 ,at times ! difficulty seem$ almo/ he>tbreak+2 b ,i w5t on1 piece by piece & atom by atom1 until ,i at la/ succe$$ 9 gett+ all ! p>ts ( ! "r /r5g? & proportion4 ,h[ to obta9 ! maximum /r5g? ) ! m9imum ( weight is "o ( !1 if n ! mo/1 difficult problems :i* ! /ud5t has to solve4 #c4 ,! !oretical reason :y weight is su* an all-important item 9 model a]oplan+1 mu* m s ?an 9 ! case ( full-size ma*9es1 is t1 g5]ally speak+1 su* models d n fly fa/ en\gh to possess a high weight c>ry+ capacity4 ,if y increase ! area ( ! support+ surface y increase also ! resi/ance1 & !reby dim9i% ! spe$1 & are no bett] (f ?an be=e4 ,! only way to increase ! weight c>ry+ capacity ( a model is to increase its spe$4 ,?is po9t w be recurr$ to lat] on4 ,"o ( ,mr4 ,t4,w4,k4 ,cl>ke's well-kn[n models1 surface area #a sq4 ft41 weight #a lb41 is /at$ to h made a flight ( #cjj y>ds c>ry+ #f oz4 ( lead4 ,?is works out approximately at #ba oz4 p] sq4 ft4 ,! velocity 7spe$7 is n /at$1 b "s e>li] models by ! same design]1 weight #a lb41 support+ area #a sq4 ft41 i4e41 at rate ( #af oz4 p] sq4 ft41 travell$ at a rate ( #cg ft4 p] second1 or #be miles an h\r4 ,! velocity ( ! =m]1 !re=e1 w\ld c]ta9ly n be less ?an #cj miles an h\r4 #d4 ,g5]ally speak+1 h[ev]1 models d n travel at any?+ l ?is velocity1 or c>ry any?+ l ?is weight p] sq4 ft4 ,an av]age assumption ( #ac to #ae miles an h\r does nor err on ! m9imum side4 ,"s v light fabric cov]$ models h a spe$ ( less ?an ev5 #aj miles an h\r4 ,su*1 ( c\rse1 _c be t]m$ effici5t models1 & c>ry only ab\t #c oz4 p] sq4 ft4 ,betwe5 ^! two types--^! two extremes--some:]e lies ! ,ideal ,model4 ,! maximum ( /r5g? ) ! m9imum ( weight c be obta9$ only3-- #a4 ,by a k ( mat]ials4 #b4 ,( h[ to comb9e ^? mat]ials 9 a mo/ effici5t & skilful mann]4 #c4 ,by a con/ant use ( ! balance or a pair ( scales1 & not+ 79 writ+7 ! weight & result ( e trial & e exp]im5t 9 ! alt]ation & *ange ( mat]ial us$4 ,,weigh ,,ev]y?+4 #e4 ,! read] mu/ n be misl$ by :at has be5 said1 & ?9k t a model mu/ n weigh any?+ if x is to fly well4 ,a heavy model w fly mu* bett] aga9/ ! w9d ?an a light "o1 provid$ t ! =m] w fly4 ,to d ?is x mu/ fly fa/4 ,to d ?is aga9 x mu/ be well p[]$1 & (f] ! m9imum ( resi/ance to ! m$ium ?r\gh :i* x moves4 ,?is means its a](oil 7support+7 surfaces mu/ be ( poli%$ wood or metal4 ,?is po9t br+s u to ! "q ( ,resi/ance1 :i* we w n[ consid]4 ,,footnotes3 #b ,a]o1 ,may #c1 #aiaj4 #c ,"p ( ?is ret>dation 01 ( c\rse1 increas$ resi/ance4 #d ,p]sonally ,i d n recomm5d alum9ium4--,v4,e4,j4 #e ,a]onautical ,j\rnal1 ,janu>y #ahig1 p4 #g4 ,,*apt] ,,ii4 ,,! ,,"q ,,( ,,resi/ance4 #a4 ,x is1 or %\ld be1 ! function ( an a]oplane--model or o!rwise--to pass ?r\gh ! m$ium 9 :i* x travels 9 su* a mann] z to leave t m$ium 9 z motionless a /ate z possible1 s9ce all motion ( ! surr\nd+ air repres5ts s mu* p[] wa/$4 ,e "p ( ! ma*9e %\ld be s con/ruct$ z to move ?r\gh ! air ) ! m9imum ( di/urbance & resi/ance4 #b4 ,! resi/ance1 consid]$ z a p]c5tage ( ! load itself1 t has to be ov]come 9 mov+ a load f "o place to ano!r1 is1 accord+ to ,mr4 ,f4,w4 ,lan*e/]1 #ab p] c5t4 9 ! case ( a fly+ ma*9e1 & #ja p] c5t4 9 ! case ( a c>go boat1 & ( a solid tyre motor c> #c p] c5t41 a locomotive #a p] c5t4 ,f\r times at lea/ ! resi/ance 9 ! case ( a]ial locomotion has to be ov]come to t obta9$ f ord9>y locomotion on l&4 ,! above ref]1 ( c\rse1 to full-siz$ ma*9es2 = a model ! resi/ance is probably ne>] #ad or #ae p] c5t4 #c4 ,?is resi/ance is made up (-- #a4 ,a]odynamic resi/ance4 #b4 ,head resi/ance4 #c4 ,sk9-friction 7surface resi/ance74 ,! fir/ results f ! necessity ( air support+ ! model dur+ flight4 ,! second is ! resi/ance (f]$ by ! framework1 wires1 edges ( a](oils1 etc4 ,! ?ird1 sk9-friction or surface resi/ance1 is v small at l[ velocities1 b increases z ! squ>e ( ! velocity4 ,to r$uce ! resi/ance :i* x sets up1 all surfaces us$ %\ld be z smoo? z possible4 ,to r$uce ! second1 cont\rs ( i*?yoid1 or fi%-l1 =m %\ld be us$1 s t ! resultant /ream-l9e fl[ ( ! m$ium %all keep 9 t\* ) ! surface ( ! body4 #d4 ,z long ago z #ahid a s]ies ( exp]im5ts 7 made by ! writ]#f to solve ! foll[+ problem3 giv5 a c]ta9 l5g? & bread?1 to f9d ! %ape :i* w (f] ! lea/ resi/ance4 ,! exp]im5ts 7 made ) a :irl+ table #dj ft4 9 diamet]1 :i* c\ld be rotat$ s t ! extremity ( ! arm rotat$ up to a spe$ ( #de miles an h\r4 ,! me?od ( exp]im5t+ 0 z foll[s3 ,! bodies 7diam4 #d 947 7 balanc$ aga9/ "o ano!r at ! extremity ( ! arm1 be+ s balanc$ t _! motions =w>d & backw>d 7 p>allel4 ,provision 0 made = accurately balanc+ ! p>allel scales on :i* ! bodies 7 susp5d$ )\t alt]+ ! resi/ance (f]$ by ! app>atus to ! air4 ,two exp]im5ts at lea/ 7to avoid error7 7 made 9 ea* case1 ! bodies be+ rev]s$ 9 ! second exp]im5t1 ! top "o be+ put at ! bottom1 & vice v]sa4 ,! conclusions arriv$ at 73-- ,= m9imum 7head7 resi/ance a body %\ld h-- #a4 ,its greate/ diamet] two-fif?s ( its entire l5g? f its head4 #b4 ,its bread? & its dep? 9 ! proportion ( f\r to ?ree4 #c4 ,its l5g? at lea/ f five to n9e times its greate/ bread? 7n9e be+ bett] ?an five74 #d4 ,a v tap]+ =m ( /]n1 ! actual /]n only be+ ( j suffici5t size to all[ ( ! propell] %aft pass+ ?r\gh4 ,9 ! case ( tw9 propell]s "s slight modification ( ! /]n w\ld be necess>y4 #e4 ,e portion ( ! body 9 contact ) ! fluid to be made z smoo? z possible4 #f4 ,a body ( su* %ape gives at mo/ only "o-tw5tie? ! resi/ance (f]$ by a flat disk ( simil> maximum sectional area4 ,results s9ce fully confirm$4 ,illu/ration3 ,,fig4 #a4--,,%ape ,,( ,,lea/ ,,resi/ance4 ,! design 9 ,fig4 #b is int]e/+1 n only because ( its probable orig91 b because ( ! %ape ( ! body & arrangem5t ( ! propell]s2 no rudd] is %[n1 & ! long /eel v]tical ma/ ext5d+ bo? upw>ds & d[nw>ds ?r\gh ! c5tre w\ld r5d] x suitable only = l&+ on wat]4 #e4 ,9 ! case ( a rubb]-driv5 model1 !re is no conta9+ body "p1 s to speak1 a long ?9 /ick1 or tubul> con/ruction if pref]r$1 be+ all t is necess>y4 ,! long ske9 ( ela/ic1 vibrat+ z well z untwi/+ z x travels ) ! ma*9e ?r\gh ! air1 (f]s "s appreciable resi/ance1 & sev]al exp]im5t]s h enclos$ x 9 a light tube made ( v ?9 v5e] wood roll$ & glu$1 or pap] ev5 may be us$2 su* tubes c be made v light1 & possess consid]able rigidity1 especially longitud9ally4 ,if ! model be a biplane1 !n all ! upright /ruts betwe5 ! two a](oils %\ld be giv5 a %ape1 a v]tical section ( :i* is %[n 9 ,fig4 #c4 #f4 ,9 consid]+ ?is "q ( resi/ance1 ! sub/ance ( :i* ! a](oil surface is made plays a v important "p1 z well z :e!r t surface be plane or curv$4 ,= "s reason n altoge!r easy to det]m9e1 fabric-cov]$ planes (f] consid]ably m resi/ance ?an wood5 or metal ones4 ,t !y %\ld (f] m resi/ance is :at common s5se w\ld lead "o to expect1 b h>dly to ! ext5t met ) 9 actual practice4 ,illu/ration3 ,,fig4 #b4--;,,design ,,= ,,an ,,a]oplane ,,model 7,,p[] ,,driv574 ,?is design is attribut$ to ,pr(essor ,langley4 ,built up fabric-cov]$ a]oplanes#g ga9 9 lightness1 b lose 9 resi/ance4 ,9 ! case ( curv$ surfaces ?is diff]5ce is consid]ably m2 "o reason1 und\bt$ly1 is t 9 a built up model surface !re is ne>ly always a t5d5cy to make ?is curvature excessive1 & mu* m ?an x %\ld be4 ,hav+ call$ att5tion to ?is "u ! head ( resi/ance1 we w leave x n[ to recur to x lat] :5 consid]+ ! a](oil prop]4 ,illu/ration3 ,,fig4 #c4--;,,horizontal ,,section ,,( ,,v]tical ,,/rut 7,,enl>g$47 #g4 ,allusion has be5 made 9 ?is *apt] to sk9 friction1 b no value giv5 = its coeffici5t4#h ,lan*e/]'s value = planes f to #a sq4 ft4 9 area1 mov+ ab\t #bj to #cj ft4 p] second1 is #jjji to #jjae4 ,pr(essor ,zahm 7,wa%+ton7 gives #jjjbf lb4 p] sq4 ft4 at #be ft4 p] second1 & at #cg ft4 p] second1 #jjje1 & ! =mula f #jjjjjjgghl#icv#ahe f be+ ! av]age friction 9 lb4 p] sq4 941 l ! l5g? 9 feet1 & v ! velocity 9 ft4 p] second4 ,he also exp]im5t$ ) v>i\s k9ds ( surfaces1 "s r\gh1 "s smoo?1 etc4 ,8 conclusion is3--,all ev5 surfaces h approximately ! same coeffici5t ( sk9 friction4 ,unev5 surfaces h a great] coeffici5t4 ,all =mul on sk9 friction mu/ at pres5t be accept$ ) res]ve4 #h4 ,! foll[+ ?ree exp]im5ts1 h[ev]1 cle>ly prove its exi/5ce1 & t x has consid]able effect3-- #a4 ,a light1 holl[ celluloid ball1 support$ on a /ream ( air project$ upw>ds f a jet1 rotates 9 "o direction or ! o!r z ! jet is incl9$ to ! left or to ! "r4 7,f4,w4 ,lan*e/]47 #b4 ,:5 a golf ball 7:i* is r\gh7 is hit s z to h consid]able und]sp91 its range is increas$ f #ace to #ahj y>ds1 due entirely to ! great] frictional resi/ance to ! air on t side on :i* ! :irl & ! progressive motion comb9e4 7,pr(4 ,tait47 #c4 ,by means ( a 7weak7 b[ a golf ball c be made to move po9t blank to a m>k #cj y>ds (f1 provid$ ! /r+ be s adju/$ z to give a good und]sp92 adju/ ! /r+ to ! c5tre ( ! ball1 in/ead ( cat*+ x bel[1 & ! drop w be ab\t #h ft4 7,pr(4 ,tait47 ,,footnotes3 #f ,vide ,inv5tion1 ,feb4 #ae1 #bb1 & #bi1 #ahif4 #g ,really a](oils1 s9ce we are consid]+ only ! support+ surface4 #h ,i4e41 to express x z a decimal fraction ( ! resi/ance1 enc\nt]$ by ! same plane :5 mov+ face in/ead ( edge on4 ,,*apt] ,,iii4 ,,! ,,"q ,,( ,,balance4 #a4 ,x is p]fectly obvi\s = successful flight t any model fly+ ma*9e 79 ! abs5ce ( a pilot7 mu/ possess a high degree ( automatic /ability4 ,! model mu/ be s con/ruct$ z to be naturally /able1 9 ! m$ium ?r\gh :i* x is propos$ to drive x4 ,! la/ rem>k is ( ! greate/ importance1 z we %all see4 #b4 ,9 connexion ) ?is same "q ( automatic /ability1 ! "q mu/ be consid]$ f ! !oretical z well z f ! practical side1 & ! lab\rs & rese>*es ( su* m5 z ,pr(essors ,brian & ,*atley1 ,f4,w4 ,lan*e/]1 ,capta9 ,f]b]1 ,m\ill>d & o!rs mu/ receive due weight4 ,_! "w _c yet be fully assess$1 b already results h be5 arriv$ at f> m important ?an are g5]ally suppos$4 ,! foll[+ are a few ( ! results arriv$ at f !oretical consid]ations2 !y _c be too widely kn[n4 7,a7 ,surfaces concave on ! "u side are n /able unless "s =m ( balanc+ device 7su* z a tail1 etc47 is us$4 7,b7 ,if an a]oplane is 9 equilibrium & mov+ uni=mly1 x is necess>y = /ability t x %all t5d t[>ds a condition ( equilibrium4 7,c7 ,9 ! case ( oscillations x is absolutely necess>y = /ability t ^! oscillations %all decrease 9 amplitude1 9 o!r words1 be damp$ out4 7,d7 ,9 a]oplanes 9 :i* ! dih$ral angle is excessive or ! c5tre ( gravity v l[ d[n1 a dang]\s pit*+ motion is q likely to be set up4 ,analogy 9 %ipbuild+--an increase 9 ! metac5tre height :ile increas+ ! /ability 9 a /atical s5se causes ! %ip to d ! same4 7,e7 ,! propell] %aft %\ld pass ?r\gh ! c5tre ( gravity ( ! ma*9e4 7,f7 ,! front planes %\ld be at a great] angle ( incl9ation ?an ! re> ones4 7,g7 ,! longitud9al /ability ( an a]oplane gr[s mu* less :5 ! a]oplane comm5ces to rise1 a monoplane becom+ un/able :5 ! angle ( asc5t is great] ?an ! incl9ation ( ! ma9 a](oil to ! horizon4 7,h7 ,head resi/ance increases /ability4 7,i7 ,?ree planes are m /able ?an two4 ,elevator--ma9 a](oil--horizontal rudd] beh9d4 7,j7 ,:5 an a]oplane is glid+ 7d[nw>ds7 /ability is great] ?an 9 horizontal flight4 7,k7 ,a l>ge mom5t ( in]tia is inimical 7oppos$7 to /ability4 7,m7 ,a]oplanes 7naturally7 /able up to a c]ta9 velocity 7spe$7 may become un/able :5 mov+ beyond t spe$4 ,possible explanation4 ,! motion ( ! air ov] ! edges ( ! a](oil becomes turbul5t1 & ! =m ( ! /ream l9es sudd5ly *anges4 ,a]oplane also probably becomes de=m$4 7,n7 ,9 a balanc$ glid] = /ability a sep>ate surface at a negative angle to ! l9e ( flight is ess5tial4 ,comp>e ,f4 7,o7 ,a keel surface %\ld be situat$ well above & beh9d ! c5tre ( gravity4 7,p7 ,an a]oplane is a cons]vative sy/em1 & /ability is greate/ :5 ! k9etic en]gy is a maximum4 ,illu/ration1 ! p5dulum4 #c4 ,ref]r+ to ,a4 ,models ) a plane or flat surface are n un/able1 & w fly well )\t a tail2 su* a ma*9e is call$ a simple monoplane4 ,illu/ration3 ,,fig4 #d4--,,"o ,,( ,,mr4 ,,burge ,,webb',s ,,simple ,,monoplanes4 ,%[+ balance weight ,a 7movable71 & also 8 w9d+-up ge>--a v h&y device4 #d4 ,ref]r+ to ,d4 ,_m model build]s make ?is mi/ake1 i4e41 ! mi/ake ( gett+ z l[ a c5tre ( gravity z possible "u ! q errone\s idea t !y are !reby increas+ ! /ability ( ! ma*9e4 ,!oretically ! c5tre ( gravity %\ld be ! c5tre ( head resi/ance1 z also ! c5tre ( pressure4 ,9 practice "s pref] to put ! c5tre ( gravity 9 models slightly above ! c5tre ( head resi/ance1 ! reason be+ t1 g5]ally speak+1 w9d gu/s h a lift+ action on ! ma*9e4 ,x mu/ be c>efully borne 9 m9d1 h[ev]1 t if ! c5tre ( w9d pressure on ! a](oil surface & ! c5tre ( gravity d n co9cide1 no matt] at :at po9t propulsive action be appli$1 x c be prov$ by q elem5t>y me*anics t su* an arrangem5t1 kn[n z ac5tric1 produces a c\ple t5d+ to upset ! ma*9e4 ,?is action is ! probable cause ( _m failures4 ,illu/ration3 ,,fig4 #e4--,,! ,,/r+fell[ ,,model ,,monoplane ,,( #ahdh4 #e4 ,ref]r+ to ,e4 ,if ! propulsive action does n pass ?r\gh ! c5tre ( gravity ! sy/em aga9 becomes ac5tric4 ,ev5 suppos+ condition ,d fulfill$1 & we arrive at ! foll[+ mo/ important result1 viz41 t = /ability3-- ,,! ,,c5tres ,,( ,,gravity1 ,,( ,,pressure1 ,,( ,,head ,,resi/ance1 ,,%\ld ,,be ,,co9cid5t1 ,,& ,,! ,,propulsive ,,action ,,( ,,! ,,propell] ,,pass ,,?r\gh ,,?is ,,same ,,po9t4 ,illu/ration3 ,,fig4 #f4--,,! ,,/r+fell[ ,,model ,,triplane ,,( #ahfh4 #f4 ,ref]r+ to ,f & ,n--! problem ( longitud9al /ability4 ,!re is "o absolutely ess5tial feature n m5tion$ 9 ,f or ,n1 & t is = automatic longitud9al /ability ! two surfaces1 ! a](oil prop] & ! balanc] 7elevator or tail1 or bo?71 mu/ be sep>at$ by "s consid]able di/ance1 a di/ance n less ?an f\r times ! wid? ( ! ma9 a](oil4#i ,m is bett]4 ,illu/ration3 ,,fig4 #g4 ,p,,naud #ahga #g4 ,) "o exception 7,pnaud7 e>ly exp]im5t]s ) model a]oplanes _h n grasp$ ?is all-important fact1 & _! models w\ld n fly1 only make a s]ies ( jumps1 because !y fail$ to balance longitud9ally4 ,9 ,/r+fell['s & ,tat9's models ! ma9 a](oil & balanc] 7tail7 are practically contigu\s4 ,pnaud 9 8 rubb]-motor$ models appe>s to h fully realis$ ?is 7vide ,fig4 #g71 & also ! necessity = us+ long /r&s ( rubb]4 ,"s ( 8 models flew #aej ft41 & %[$ consid]able /ability4 ,illu/ration3 ,,fig4 #h4--,,tat9',s ,,a]oplane 7#ahgi74 ,surface #jg sq4 metres1 total weight #age kilogrammes1 velocity ( su/5tation #h metres a second4 ,motor1 compress$ air 7= description see #bc1 *4 iv74 ,revolv$ r\nd & r\nd a track te!r$ to a po/ at ! c5tre4 ,9 "o ( its jumps x cle>$ ! head ( a spectator4 ,) ?ree surfaces "o w\ld set ! elevator at a slight plus angle1 ma9 a](oil horizontal 7nei!r positive nor negative71 & ! tail at a correspond+ negative angle to ! positive "o ( ! elevator4 ,ref]r+ to ,o4#aj ,"o w\ld naturally be incl9$ to put a keel surface--or1 9 o!r words1 v]tical f9s--b5ea? ! c5tre ( gravity1 b ,d %[s u ?is may h ! opposite effect to :at we might expect4 ,9 full-siz$ ma*9es1 ^? 9 :i* ! di/ance betwe5 ! ma9 a](oil & balanc]s is consid]able 7l ! ,f>man7 %[ consid]able automatic longitud9al /ability1 & ^? 9 :i* x is %ort 7l ! ,wright7 are purposely made s ) ! idea ( do+ away ) x1 & r5d]+ ! ma*9e quick] & m s5sitive to p]sonal control4 ,9 ! case ( ! ,/r+fell[ & ,tat9 models we h ! extreme case--practically ! bird entirely volitional & p]sonal--:i* is ! opposite 9 e way to :at we desire on a model "u no p]sonal or volitional control at all4 ,illu/ration3 ,,fig4 #i4--;,,cl>k',s ,,model ,,fly]4 ,ma9 a](oil set at a slight negative angle4 ,dih$ral angles on bo? a](oils4 ,! !oretical conditions /at$ 9 ,f & ,n are fully borne out 9 practice4 ,& s9ce a curv$ a](oil ev5 :5 set at a slight negative angle has /ill consid]able p[]s ( su/5tation1 x is possible to give ! ma9 a](oil a slight negative angle & ! elevator a slight positive "o4 ,?is fact is ( ! greate/ importance1 s9ce x enables u to c\nt]act ! effect ( ! travel ( ! c5tre ( pressure4#aa ,illu/ration3 ,,fig4 #aj4--,,l>ge ,,model ,,monoplane4 ,design$ & con/ruct$ by ! au?or1 ) v]tical f9 7no dih$ral angle74 ,) a l>g] & m effici5t propell] ?an ! "o "h %[n "s excell5t flights 7 obta9$4 ,con/ruct$ ( bamboo & na9sook4 ,/ay$ ) /eel wire4 #h4 ,ref]r+ to ,i4 ,?is1 aga91 is ( prim>y importance 9 longitud9al /ability4 ,! ,f>man ma*9e has ?ree su* planes--elevator1 ma9 a](oil1 tail ! ,wright orig9ally _h n1 b is n[ be+ fitt$ ) a tail1 & exp]im5ts on ! ,%ort-,wright biplane h q prov$ its /abilis+ effici5cy4 ,! ?ree plane 7triple monoplane7 9 ! case ( models has be5 tri$1 b possesses no advantage s f> ov] ! d\ble monoplane type4 ,! writ] has made _m exp]im5ts ) v]tical f9s1 & has f\nd ! ma*9e v /able1 ev5 :5 ! f9 or v]tical keel is plac$ "s di/ance above ! c5tre ( gravity4 #i4 ,! "q ( transv]se 7side to side7 /ability at once br+s u to ! "q ( ! dih$ral angle1 practically simil> 9 its action to a flat plane ) v]tical f9s4 ,illu/ration3 ,,fig4 #aa4--,,sir ,,george ,,cayley',s ,,fly+ ,,ma*9e4 ,eight fea!rs1 two corks1 a ?9 rod1 a piece ( :alebone1 & a piece ( ?read4 #aj4 ,! sett+ up ( ! front surface at an angle to ! re>1 or ! sett+ ( ^! at correspond+ comp5satory angles already dealt )1 is no?+ m nor less ?an ! pr9ciple ( ! dih$ral angle = longitud9al /ability4 ,illu/ration3 ,,fig4 #ab4--,,v>i\s ,,=ms ,,( ,,dih$rals4 ,z e>ly z ! comm5cem5t ( la/ c5tury ,sir ,george ,cayley 7a man m ?an a hundr$ ye>s ahead ( 8 times7 0 ! fir/ to po9t out t two planes at a dih$ral angle con/itute a basis ( /ability4 ,=1 on ! ma*9e heel+ ov]1 ! side :i* is requir$ to rise ga9s resi/ance by its new position1 & t :i* is requir$ to s9k loses x4 #aa4 ,! dih$ral angle pr9ciple may take _m =ms4 ,z 9 ,fig4 #ab a is a monoplane1 ! re/ biplanes4 ,! angles & curves are some:at exagg]at$4 ,x is q a mi/ake to make ! angle excessive1 ! lift be+ !reby dim9i%$4 ,a few degrees %\ld suffice4 ,:il/ x is evid5t en\gh t transv]se /ability is promot$ by mak+ ! su/a9+ surface tr\gh-%ap$1 x is n s evid5t :at =m ( cross section is ! mo/ effici5t = su/5tation & equilibrium comb9$4 ,illu/ration3 ,,fig4 #ac4 ,x is evid5t t ! right+ mom5t ( a unit ( surface ( an a]oplane is great] at ! out] edge ?an else:]e1 ow+ to ! great] lev] arm4 #ab4 ,! upturn$ tip dih$ral c]ta9ly appe>s to h ! advantage4 ,! out] edges ( ! a](oil !n %\ld be turn$ upw>d = ! purpose ( transv]se /ability1 :ile ! inn] surface %\ld rema9 flat or concave = great] support4 #ac4 ,! exact mo/ fav\rable outl9e ( transv]se section = /ability1 /ead9ess & buoyancy has n yet be5 f\nd2 b ! writ] has f\nd ! section giv5 9 ,fig4 #ac1 a v effici5t "o4 ,,footnotes3 #i ,if ! wid? be n uni=m ! mean wid? %\ld be tak54 #aj ,?is ref]s1 ( c\rse1 to transv]se /ability4 #aa ,see *4 vi4 ,,*apt] ,,iv4 ,,! ,,motive ,,p[]4 ,,section ,i4--,,rubb] ,,motors4 #a4 ,"s =ty ye>s h elaps$ s9ce ,pnaud fir/ us$ ela/ic 7rubb]7 = model a]oplanes1 & dur+ t "t no bett] sub/itute 79 spite ( innum]able exp]im5ts7 has be5 f\nd4 ,nor = ! small] & light] class ( models is !re any likelihood ( rubb] be+ displac$4 ,su* be+ ! case1 a brief acc\nt ( "s exp]im5ts on ?is sub/ance z a motive p[] = ! same may n be )\t int]e/4 ,! ^w ela/ic 79 sci5ce7 d5otes3 ! t5d5cy :i* a body has :5 di/ort$ to return to its orig9al %ape4 ,glass & ivory 7)9 c]ta9 limits7 are two ( ! mo/ ela/ic bodies kn[n4 ,b ! limits )9 :i* mo/ bodies c be di/ort$ 7twi/$ or /ret*$1 or bo?7 )\t ei!r fracture or a ,,l>ge p]man5t alt]ation ( %ape is v small4 ,n s rubb]--x f> surpasses 9 ?is respect ev5 /eel spr+s4 #b4 ,let u take a piece ( ela/ic 7rubb]7 cord1 & /ret* x ) kn[n weights & obs]ve c>efully :at happ5s4 ,we %all f9d t1 fir/ ( all3 ! ext5sion is proportional to ! weight susp5d$--b soon we h an increas+ increase ( ext5sion4 ,9 "o exp]im5t made by ! writ]1 :5 ! weights 7 remov$ ! rubb] cord rema9$ #a_/h ( an in* long]1 & at ! end ( an h\r recov]$ itself to ! ext5t ( #a_/af1 rema9+ f9ally p]man5tly #a_/af ( an in* long]4 ,l5g? ( ela/ic cord us$ 9 ?is exp]im5t #h-a_/h in*es1 #c_/af ( an in* ?ick4 ,susp5d$ weights1 #a oz4 up to #fd oz4 ,ext5sion f in* up to #bd-e_/h in*es4 ,graph drawn 9 ,fig4 #ad1 ,no4 ,b absciss ext5sion 9 eigh?s ( an in*1 ord9ates weights 9 ounces4 ,s long z ! graph is a /raight l9e x %[s ! ext5sion is proportional to ! susp5d$ weight2 aft]w>ds 9 excess4 ,illu/ration3 ,,fig4 #ad4--,,weight ,,& ,,ext5sion4 ,b1 rubb] #c_/af 94 ?ick2 ,c1 #b_/af 94 ?ick2 ,d1 #a_/af 94 ?ick4 ,a1 !oretical l9e if ext5sion 7 proportional to weight4 ,9 ?is exp]im5t we h be5 able to /ret* 7di/ort7 a piece ( rubb] to m ?an ?ree times its orig9al l5g?1 & aft]w>ds x f9ally returns to almo/ its orig9al l5g?3 n only s1 a piece ( rubb] cord c be /ret*$ to eight or n9e times its orig9al l5g? )\t fracture4 ,h]e9 lies its supreme advantage ov] /eel or o!r spr+s4 ,weight = weight m en]gy c be got or m "w be done by /ret*$ 7or twi/$1 or1 to speak m correctly1 by /ret*$-twi/$7 rubb] cord ?an f any =m ( /eel spr+4#ab ,x is true x is /ret*$--twi/$--f> beyond :at is call$ ! ela/ic limit1 & its effici5cy falls (f1 b ) c>e n ne>ly s quickly z is commonly suppos$1 b 9 spite ( ?is & o!r drawbacks its advantages f> m ?an c\nt]balance ^!4 #c4 ,exp]im5t+ ) cords ( v>y+ ?ickness we f9d t3 ! ext5sion is inv]sely proportional to ! ?ickness4 ,if we leave a weight hang+ on a piece ( rubb] cord 7/ret*$1 ( c\rse1 beyond its ela/ic limit7 we f9d t3 ! cord cont9ues to elongate z long z ! weight is left on4 ,= example3 a #a lb4 weight hung on a piece ( rubb] cord1 #h-a_/h in*es long & #a_/h ( an in* ?ick1 /ret*$ x--at fir/--#f in*es2 aft] two m9utes ?is _h increas$ to #f-e_/h 7#c_/h ( an in* m74 ,"o h\r lat] #a_/h ( an in* m1 & sixte5 h\rs lat] #a_/h ( an in* m1 i4e4 a sixte5 h\rs' hang produc$ an additional ext5sion ( ( an in*4 ,on a ?9n] cord 7half ! ?ickness7 same weight produc$ an additional ext5sion 7aft] #ad h\rs7 ( #aj-c_/h 94 ,n4,b4--,an ela/ic cord or spr+ balance %\ld nev] h a weight left p]man5tly on x--or be subject$ to a di/ort+ =ce = a long] "t ?an necess>y1 or x w take a p]man5t set1 & n return to ev5 approximately its orig9al l5g? or =m4 ,9 a rubb] cord ! ext5sion is directly proportional to ! l5g? z well z inv]sely proportional to ! ?ickness & to ! weight susp5d$--true only )9 ! limits ( ela/icity4 ,illu/ration3 ,,fig4 #ae4--;,,ext5sion ,,& ,,increase ,,9 ,,volume4 #d4 ,:5 a ,rubb] ,cord is /ret*$ !re is an ,increase ( ,volume4--,on /ret*+ a piece ( rubb] cord to twice its orig9al 7natural7 l5g?1 we %\ld p]haps expect to f9d t ! /r+ w\ld only be half z ?ick1 z w\ld be ! case if ! volume rema9$ ! same4 ,p]=m+ ! exp]im5t1 & measur+ ! cord z accurately z possible ) a micromet]1 measur+ to ! "o-?\s&? ( an in*1 we at once p]ceive t ?is is n ! case1 be+ ab\t two-?irds ( its =m] volume4 #e4 ,9 ! case ( rubb] cord us$ = a motive p[] on model a]oplanes1 ! rubb] is bo? twi/$ & /ret*$1 b *iefly ! latt]4 ,?irty-six /r&s ( rubb]1 weight ab\t #ef grammes1 at #aej turns give a torque ( #d oz4 on a #e-;94 arm1 b an end ?ru/1 or end pull1 ( ab\t #c lb4 7,ball be>+s1 or "s su* device1 c be us$ to obviate ?is end ?ru/ :5 desirable47 ,a s]ies ( exp]im5ts und]tak5 by ! writ] on ! torque produc$ by twi/$ rubb] /r&s1 v>y+ 9 numb]1 l5g?1 etc41 & aft]w>ds c>efully plott$ out 9 graph =m1 h l$ to "s v int]e/+ & in/ructive results4 ,ball be>+s 7 us$1 & ! torque1 measur$ 9 eigh?s ( an ounce1 0 tak5 79 ea* case7 f an arm #e 94 9 l5g?4 ,! foll[+ are ! pr9cipal results arriv$ at4 ,= graphs1 see ,fig4 #af4 #f4 ,a4 ,increas+ ! numb] ( 7rubb]7 /r&s by "o-half 7l5g? & ?ickness ( rubb] rema9+ con/ant7 increases ! torque 7unw9d+ t5d5cy7 tw(old1 i4e41 d\bles ! motive p[]4 ,b4 ,d\bl+ ! numb] ( /r&s increases ! torque m ?an ?ree times--ab\t #c-a_/c times1 #c times up to #ajj turns1 #c times f #ajj to #bej turns4 ,c4 ,trebl+ ! numb] ( /r&s increases ! torque at lea/ sev5 times4 ,! increas$ size ( ! coils1 & !reby increas$ ext5sion1 expla9s ?is result4 ,z we increase ! numb] ( /r&s1 ! numb] ( twi/s or turns t c be giv5 x becomes less4 ,d4 ,d\bl+ ! numb] ( /r&s 7l5g?1 etc41 rema9+ con/ant7 dim9i%es ! numb] ( turns by "o-?ird to "o-half4 7,9 few /r&s "o-?ird1 9 #cj & ov] "o-half47 ,illu/ration3 ,,fig4 #af4--,,torque ,,graphs ,,( ,,rubb] ,,motors4 ,absciss ,turns4 ,ord9ates ,torque measur$ 9 #a_/af ( an oz4 ,l5g? ( arm1 #e 94 ,a4 #ch /r&s ( new rubb]1 #b ft4 #f 94 long2 #eh grammes weight4 ,b4 #cf /r&s1 #b ft4 #f 94 long2 end ?ru/ at #aej turns1 #c lb4 ,c4 #cb /r&s1 #b ft4 #f 94 long4 ,d4 #bd ,e4 #ah weight #bh grammes4 ,f4 #ab #a ft4 #c 94 long ,g4 #ab #b ft4 #f 94 long4 ,e4 ,if we halve ! l5g? ( ! rubb] /r&s1 keep+ ! numb] ( /r&s ! same1 ! torque is b slightly increas$ = ! fir/ #ajj turns2 at #bdj turns x is d\ble4 ,b ! great] numb] ( turns--9 ratio ( ab\t #b3a--t c be giv5 ! long] /r& mu* m ?an comp5sates = ?is4 ,f4 ,no arrangem5t ( ! /r&s1 p] se1 gets m en]gy 7m motive p[]7 out ( !m ?an any o!r1 b !re are special reasons = mak+ ! /r&s-- ,g4 ,z long & z few 9 numb] z possible4 #a4 ,m turns c be giv5 x4 #b4 ,x gives a f> m ev5 torque4 ,twelve /r&s #b ft4 #f 94 long give practically a l9e ( small con/ant angle4 ,?irty-six /r&s same l5g? a mu* /eep] angle1 ) consid]able v>iations4 ,a v good result1 :i* ! writ] has v]ifi$ 9 practice1 pay+ due reg>d to bo? propell] & motor1 is to make-- ,h4 ,! l5g? ( ! rubb] /r&s twice#ac 9 feet ! numb] ( ! /r&s 9 in*es1#ad e4g41 if ! numb] ( /r&s is #ab _! l5g? %\ld be #b ft41 if #ah1 #c ft41 & s on4 #g4 ,exp]im5ts ) #cb to #ch /r&s #b ft4 #f 94 long give a torque curve almo/ precisely simil> to t obta9$ f exp]im5ts made ) flat spiral /eel spr+s1 simil> to ^? us$ 9 wat*es & clocks2 &1 z we "k1 ! torque giv5 by su* spr+s is v unev51 & has to be equalis$ by use ( a fusee1 or "s su* device4 ,9 ! case ( su* spr+s x mu/ n be =gott5 t ! turn+ mom5t 7unw9d+ t5d5cy7 is ,,n proportional to ! am\nt ( w9d+ up1 ?is be+ true only 9 ! balance spr+s ( wat*es1 etc41 :]e bo? ends ( ! spr+ are rigidly fa/5$4 ,9 ! case ( ,,spr+ ,,motors4#ae ,i4 ,! turn+ mom5t 7unw9d+ t5d5cy7 is proportional to ! diff]5ce betwe5 ! angle ( w9d+ & yield+1 proportional to ! mom5t ( in]tia ( its section1 i4e41 to ! bread? & ! cube ( its ?ickness1 also proportional to ! modulus ( ela/icity ( ! sub/ance us$1 & inv]sely proportional to ! l5g? ( ! /rip4 #h4 ,ref]r+ back to ,a1 ,b1 ,c1 !re are "o or two practical d$uctions :i* %\ld be c>efully not$4 ,suppos+ we h a model ) "o propell] & #cf /r&s ( ela/ic4 ,if we decide to fit x ) tw9 screws1 !n1 o!r reasons ap>t1 we %all require two sets ( /r&s ( m ?an #ah 9 numb] ea* to h ! same motive p[] 7#bg if ! same torque be requir$74#af ,?is is an important po9t1 & "o n to be lo/ sight ( :5 ?9k+ ( us+ two propell]s4 ,exp]im5ts on-- #i4 ,! ,numb] ( ,revolutions 7turns7 t c be giv5 to ,rubb] ,motors l$ to int]e/+ results1 e4g41 ! numb] ( turns to produce a d\ble knot 9 ! cord f end to end 71 9 ! case ( rubb]1 "o y>d long3-- ,no4 ( ,/r&s4 ,no4 ( ,turns4 ,no4 ( ,/r&s4 ,no4 ( ,turns4 #d #ddj #af #bjj #h #caj #bh #agj #ab #bej ,x w be at once notic$ t ! great] ! numb] ( rubb] /r&s us$ 9 a giv5 l5g?1 ! few] turns w x /& 9 proportion4 ,= in/ance1 #h /r&s d\ble knot at #caj1 & #d at #ddj 7& n at #fbj71 #af at #bjj1 & #h at #caj 7& n #djj71 & s on4 ,! reason1 ( c\rse1 is ! m ! /r&s ! great] ! di/ance !y h to travel r\nd !mselves4 #aj4 ,! ,maximum ,numb] ( ,turns4--,z to ! maximum numb] ( p]missible turns1 rubb] has rupture /ress ( #ccj lb4 p] sq4 941 b a v high p]missible /ress1 z mu* z #hj p] c5t4 ,! resili5ce 7p[] ( recov]y aft] di/ortion7 9 t5sion ( rubb] is 9 consid]able excess ( any o!r sub/ance1 silk be+ ! only o!r sub/ance :i* at all approa*es x 9 ?is respect1 ! ratio be+ ab\t #aa 3 #i4 ,! resili5ce ( /eel spiral spr+ is v slight 9 comp>ison4 ,a rubb] motor 9 :i* ! d\ble knot is n exce$$ by m ?an #ajj turns 7rubb] "o y>d 9 l5g?7 %\ld la/ a good "t4 ,:5 try+ = a record flight1 us+ new ela/ic1 z _m z ev5 #ejj or #fjj or ev5 m turns h be5 giv5 9 ! case ( #cb-cf /r&s a y>d 9 l5g?2 b su* a sev]e /ra9 soon spoils ! rubb]4 #aa4 ,on ! ,use ( ,lubricants4--,"o ( ! drawbacks to rubb] is t if x be excessively /ra9$ x soon beg9s to break up4 ,"o ( ! *ief causes ( ?is is t ! /r&s /ick toge!r--!y %\ld always be c>efully sep>at$1 if necess>y1 aft] a flight--& an undue /ra9 is !reby ca/ on c]ta9 p>ts4 ,ap>t also f ?is ! v>i\s /r&s are n subject to ! same t5sion4 ,x has be5 sugge/$ t if "s means c\ld be devis$ to prev5t ?is1 & all[ ! /r&s to slip ov] "o ano!r1 a consid]able increase ( p[] might result4 ,x mu/1 h[ev]1 be c>efully borne 9 m9d t any?+ ( an oily or greasy nature has an injuri\s effect on ! rubb]1 & mu/ be avoid$ at all co/s4 ,b5zol1 petroleum1 e!r1 volatile oils1 turp5t9e1 *lor(orm1 naph?a1 vasel9e1 soap1 & all k9ds ( oil mu/ be c>efully avoid$1 z !y s(t5 ! rubb]1 & r$uce x m or less to ! consi/5ce ( a /icky mass4 ,! only oil :i* is said to h no action on rubb]1 or practically none1 is ca/or oil2 all ! same1 ,i d n advise its use z a lubricant4 ,!re are ?ree only :i* we ne$ consid]3-- #a4 ,soda & wat]4 #b4 ,fr5* *alk4 #c4 ,pure r$i/ill$ glyc]9e4 ,! fir/ is p]fectly satisfactory :5 fre%ly appli$1 b soon dries up & evaporates4 ,! second falls (f2 & unless ! *alk be ( ! s(te/ k9d1 free f all grit & h>d p>ticles1 x w soon d m h>m ?an good4 ,! ?ird1 glyc]9e1 is = ord9>y purposes by f> ! be/1 & has a b5eficial r ?an a delet]i\s effect on ! rubb]2 b x mu/ be pure4 ,! r$i/ill$ k9d1 free f all traces ( ars5ic1 grease1 etc41 is ! only k9d p]missible4 ,x does n evaporate1 & a few drops1 comp>atively speak+1 w lubricate fifty or sixty y>ds ( rubb]4 ,be+ ( a /icky or tacky nature x naturally ga!rs up du/ & p>ticles ( dirt 9 c\rse ( "t4 ,to prev5t ^! gr9d+ into ! rubb]1 wa% x f "t to "t 9 w>m soda1 & w>m & apply fre% glyc]9e :5 requir$4 ,glyc]9e1 unlike vasel9e 7a product ( petroleum71 is n a grease2 x is =m$ f fats by a process kn[n z saponification1 or treatm5t ( ! oil ) cau/ic alkali1 :i* decomposes ! comp\nd1 =m+ an alkal9e /e>ate 7soap71 & lib]at+ ! glyc]9e :i* rema9s 9 solution :5 ! soap is sep>at$ by ?r[+ 9 common salt4 ,9 ord] to obta9 pure glyc]9e1 ! fat c be decompos$ by lead oxide1 ! glyc]9e rema9+ 9 solution1 & ! lead soap or pla/] be+ precipitat$4 ,by us+ glyc]9e z a lubricant ! numb] ( turns t c be giv5 a rubb] motor is greatly increas$1 & ! coils slip ov] "o ano!r freely & easily1 & prev5t ! ?r[+ ( undue /ra9 on "s p>ticul> portion1 & absolutely prev5t ! /r&s f /ick+ toge!r4 #ab4 ,! ,action ( ,copp] ^u ,rubb]4--,copp]1 :e!r 9 ! =m ( ! metal1 ! oxides1 or ! soluble salts1 has a m>k$ injuri\s action ^u rubb]4 ,9 ! case ( metallic copp] ?is action has be5 attribut$ to oxidation induc$ by ! dissolv$ oxyg5 9 ! copp]4 ,9 work+ draw+s = model a]oplanes ,i h notic$ designs 9 :i* ! hooks on :i* ! rubb] /r&s 7 to be /ret*$ 7 made ( copp]4 ,9 no case %\ld ! /r&s be plac$ ^u b>e metal4 ,i always cov] m9e ) a piece ( valve tub+1 :i* c easily be r5ew$ f "t to "t4 #ab;,a4 ,! ,action ( ,wat]1 etc41 on ,rubb]4--,rubb] is q insoluble 9 wat]2 b x mu/ n be =gott5 t x w absorb ab\t #be p] c5t4 into its pores aft] soak+ = "s "t4 ,e!r1 *lor(orm1 c>bon-tetra*loride1 turp5t9e1 c>bon bi-sulphide1 petroleum _s1 b5z5e & its homologues f\nd 9 coal-t> naph?a1 dissolve rubb] readily4 ,alcohol is absorb$ by rubb]1 b is n a solv5t ( x4 #ab;,b4 ,h[ to ,pres]ve ,rubb]4--,9 ! fir/ place1 9 ord] t x %all be possible to pres]ve & keep rubb] 9 ! be/ condition ( effici5cy1 x is absolutely ess5tial t ! rubb] %all be1 :5 obta9$1 fre% & ( ! be/ k9d4 ,only ! be/ ,p>a rubb] %\ld be b\ght2 to obta9 x fre% x %\ld be got 9 z l>ge quantities z possible direct f a manufactur] or reliable rubb] %op4 ,! composition ( ! be/ ,p>a rubb] is z foll[s3--,c>bon1 #hgdf p] c5t42 hydrog51 #abjj p] c5t42 oxyg5 & a%1 #jed p] c5t4 ,9 ord] to increase its ela/icity ! pure rubb] has to be vulcanis$ be=e be+ made into ! %eet "s sixty or eighty y>ds 9 l5g?1 f :i* ! rubb] ?reads are cut2 aft] vulcanization ! sub/ance consi/s ( rubb] plus ab\t #c p] c5t4 ( sulphur4 ,n[1 un=tunately1 ! pres5ce ( ! sulphur makes ! rubb] m prone to atmosph]ic oxidation4 ,vulcaniz$ rubb]1 comp>$ to pure rubb]1 has !n b a limit$ life4 ,x is to ?is process ( oxidation t ! m or less rapid det]ioration ( rubb] is due4 ,to pres]ve rubb] x %\ld be kept f ! sun's rays1 or1 inde$1 any act9ic rays1 9 a cool1 airy place1 & subject$ to z ev5 a temp]ature z possible4 ,great extremes ( temp]ature h a v injuri\s effect on rubb]1 & x %\ld be wa%$ f "t to "t 9 w>m soda wat]4 ,x %\ld be subject$ to no t5sion or compression4 ,det]iorat$ rubb] is absolutely useless = model a]oplanes4 #ac4 ,to ,te/ ,rubb]4--,good ela/ic ?read compos$ ( pure ,p>a rubb] & sulphur %\ld1 if prop]ly made1 /ret* to sev5 times its l5g?1 & !n return to its orig9al l5g?4 ,x %\ld also possess a /ret*+ limit at lea/ t5 times its orig9al l5g?4 ,z already /at$1 ! ?reads or /r&s are cut f %eets2 ^! ?reads c n[ be cut fifty to ! in*4 ,= rubb] motors a v great deal s f> z l5g? ( life dep5ds on ! accuracy & skill ) :i* ! /r&s are cut4 ,:5 exam9$ "u a microscope 7n too p[]ful7 ! /r&s hav+ ! lea/ ragg$ edge1 i4e41 ! be/ cut1 are to be pref]r$4 #ad4 ,! ,section--,/rip or ,ribbon v]sus ,squ>e4--,9 section ! squ>e & n ! ribbon or /rip %\ld be us$4 ,! edge ( ! /rip ,i h always f\nd m ragg$ "u ! microscope ?an ! squ>e4 ,i h also f\nd x less effici5t4 ,!oretically no d\bt a r\nd section w\ld be be/1 b none su* 79 small sizes7 is on ! m>ket4 ,models h be5 fitt$ ) a tubul> section1 b su* %\ld on no acc\nt be us$4 #ae4 ,size ( ! ,section4--,"o-sixte5? or "o-twelf? is ! be/ size = ord9>y models2 p]sonally1 ,i pref] ! ?9n]4 ,if m ?an a c]ta9 numb] ( /r&s are requir$ to provide ! necess>y p[]1 a l>g] size %\ld be us$4 ,x is n easy to say :at ?is numb] is1 b fifty may probably be tak5 z an outside limit4 ,rememb] ! size increases by area section2 twice ! sectional height & bread? means f\r times ! rubb]4 #af4 ,ge>$ ,rubb] ,motors4--,x is q a mi/ake to suppose t any advantage c be obta9$ by us+ a f\r to "o ge>+1 say2 all t y d obta9 is "o-f\r? ( ! p[] m9us ! increas$ friction1 m9us ! add$ weight4 ,?is presumes1 ( c\rse1 y make no alt]ation 9 y\r rubb] /r&s4 ,ge>+ su* z ?is means %ort rubb] /r&s1 & su* are n to be desir$2 9 any case1 !re is ! difficulty ( increas$ friction & add$ weight to ov]come4 ,x is true by splitt+ up y\r rubb] motor into two sets ( /r&s in/ead ( "o y c obta9 m turns1 b1 z we h se51 y mu/ increase ! numb] ( /r&s to get ! same ?ru/1 & y h ?is to c\nt]act any advantage y ga9 z well z add$ weight & friction4 #ag4 ,! writ] has tri$ endless exp]im5ts ) all k9ds ( ge>$ rubb] motors1 & ! only "o wor? a mom5t's consid]ation is ! foll[+1 viz41 "o 9 :i* two ge> :eels--same size1 weight1 & numb] ( tee?--are made use (1 ! propell] be+ atta*$ to ! axle ( "o ( !m1 & ! same numb] ( /r&s are us$ on ea* axle4 ,! success or non-success ( ?is motor dep5ds entirely on ! me?od us$ 9 its con/ruction4 ,at fir/ sight x may appe> t no great skill is requir$ 9 ! con/ruction ( su* a simple piece ( app>atus4 ,no great] mi/ake c\ld be made4 ,x is absolutely necess>y t ! friction & weight be r$uc$ to a m9imum1 & ! /r5g? be a maximum4 ,! torque ( ! rubb] /r&s on s %ort an arm is v great4 ,ord9>y light brass cog:eels w n /& ! /ra94 ,a4 ,! cog:eels %\ld be ( /eel#ag & accurately cut ( diamet] suffici5t to sep>ate ! two /r&s ! requisite di/ance1 b no m4 ,b4 ,! weight mu/ be a m9imum4 ,?is is be/ atta9$ by us+ solid :eels1 & light5+ by drill+ & turn+4 ,c4 ,! friction mu/ be a m9imum4 ,use ! lighte/ ball be>+s obta9able 7^! weigh only #jc gramme71 adju/ ! :eels s t !y run ) ! greate/ fre$om1 b see t ! tee? ov]lap suffici5tly to /& ! /ra9 & slight v>iations 9 direction )\t fe> ( slipp+4 ,%all[ tee? are useless4 ,d4 ,use vasel9e on ! cogs to make !m run z easily z possible4 ,illu/ration3 ,,fig4 #ag4--;,,ge>$ ,,rubb] ,,motor4 ,design$ & con/ruct$ by ! writ]4 ,= description ( ! model1 etc41 see ,app5dix4 ,e4 ,! mat]ial ( ! conta9+ framework mu/ be ( maximum /r5g? & m9imum lightness4 ,con/ruct x ( m9imum size1 box %ap$1 use ! ?9ne/ t9 7really t9n$ %eet-iron7 procurable1 & light5 by drill+ holes1 n too l>ge1 all ov] x4 ,d n use alum9ium or magnalium4 ,/eel1 c\ld x be procur$ ?9 en\gh1 w\ld be bett] /ill4 ,f4 ,use /eel pian(orte wire = ! sp9dles1 & hooks = ! rubb] /r&s1 us+ z ?9 wire z w /& ! /ra94 ,unless ^! directions are c>efully c>ri$ out no advantage w be ga9$--! writ] speaks f exp]i5ce4 ,! requisite numb] ( rubb] /r&s to give ! be/ result mu/ be det]m9$ by exp]im5t4 #ah4 ,"o advantage 9 us+ su* a motor z ?is is t ! two equal /r&s untwi/+ 9 opposite directions h a decid$ /eady+ effect on ! model1 simil> almo/ to ! case 9 :i* two propell]s are us$4 ,! be/ model flights t ! writ] has a*iev$ h be5 obta9$ ) a motor ( ?is description4#ah ,9 ! case ( tw9 screws two su* ge>+s c be us$1 & ! rubb] split up into f\r /r&s4 ,! conta9+ framework 9 ?is case c be simply light pieces ( tub+ let into ! wood5 framework1 or v light iron pieces fa/5$ !reto4 ,d n attempt to split up ! rubb] into m ?an two /r&s to ea* propell]4 ,,section ,,ii4--,,o!r ,,=ms ,,( ,,motors4 #ah;,a4 ,spr+ ,motors4--,?is "q has already be5 dealt ) m or less :il/ deal+ ) rubb] motors1 & ! sup]iority ( ! latt] ov] ! =m] po9t$ out4 ,rubb] has a mu* great] sup]iority ov] /eel or o!r spr+s1 because 9 /ret*-twi/$ rubb] f> m en]gy c be /or$ up weight = weight4 ,"o p\nd weight ( ela/ic c be made to /ore up "s #cbj ft4-lb4 ( en]gy1 & /eel only "s #fe lb4 ,& 9 addition to ?is !re is ! "q ( ge>+1 involv+ extra weight & friction2 t is1 if flat /eel spr+s simil> to ^? us$ 9 clockwork me*anism be made use (1 z is g5]ally ! case4 ,! only in/ance 9 :i* su* spr+s are ( use is = ! purpose ( /udy+ ! effects ( diff]5t di/ributions ( weight on ! model1 & its effect on ! balance ( ! ma*9e2 b effects su* z ?is c be br\ght ab\t )\t a *ange ( motor4 #ah;,b4 ,a m effici5t =m ( spr+ motor1 do+ away ) ge>+ tr\bles1 is to use a long spiral spr+ 7z long z ! rubb] /r&s7 made ( m$ium-siz$ piano wire1 simil> 9 pr9ciple to ^? us$ 9 "s roll]-bl9ds1 b long] & ( ?9n] /eel4 ,! writ] has exp]im5t$ ) su*1 z well z scores ( o!r =ms ( spr+ motors1 b none c comp>e ) rubb]4 ,! long spiral =m ( /eel spr+ is1 h[ev]1 mu* ! be/4 #ah;,c4 ,compress$ ,air ,motors4--,?is is a v fasc9at+ =m ( motor1 on pap]1 & appe>s at fir/ sight ! ideal =m4 ,x is s easy to write3 ,its weight is negligible1 & x c be provid$ free ( co/2 all t is necess>y is to "w a bicycle pump = z _m m9utes z ! motor is desir$ to run4 ,?is /or$-up en]gy c be conta9$ 9 a m]e tube1 ( alum9ium or magnalium1 =m+ ! c5tral rib ( ! ma*9e1 & ! eng9e me*anism necess>y = convey+ ?is /or$-up en]gy to ! revolv+ propell] ne$ weigh only a few ounces4 ,ano!r writ] recomm5ds a pressure ( #cjj lb4 #ah;,d4 ,a pneumatic drill g5]ally works at ab\t #hj lb4 pressure1 & :5 develop+ #a horse-p[]1 uses ab\t #ee cubic ft4 ( free air p] m9ute4 ,n[ if we apply ?is to a model a]oplane ( av]age size1 tak+ a res]voir #c ft4 long by #a 94 int]nal diamet]1 made ( magnalium1 say--/eel w\ld1 ( c\rse1 be mu* bett]--! weight ( :i* w\ld c]ta9ly n be less ?an #d oz41 we f9d t at #hj lb4 pressure su* a motor w\ld use #ee_/;,horse ,p[] 7,h4,p47 cub4 ft4 p] m9ute4 ,n[ #hj lb4 is ab\t #e atmosph]es1 & ! cubical cont5ts ( ! above motor "s #fc cub4 94 ,! "t dur+ :i* su* a model w\ld fly dep5ds on ! ,h4,p4 necess>y = flight2 b a fair all[ance gives a flight ( f #aj to #cj sec4 ,i take #hj lb4 pressure z a fair practical limit4 #ah;,e4 ,! pressure 9 a motor-c> tyre runs f #dj to #hj lb41 usually ab\t #gj lb4 ,n[ #bfj /rokes are requir$ ) an ord9>y inflator to obta9 s l[ a pressure z #gj lb41 & x is no easy job1 z ^? :o h done x "k4 #ai4 ,prior to #ahic ,mr4 ,h>graves 7( cellul> kite fame7 /udi$ ! "q ( compress$-air motors = model fly+ ma*9es4 ,8 motor 0 describ$ z a m>vel ( simplicity & lightness1 its cyl9d] 0 made l a common t9 c1 ! cyl9d] cov]s cut f %eet t9 & press$ to %ape1 ! pi/on & junk r+s ( ebonite4 ,"o ( 8 receiv]s 0 #bc-c_/h 94 long1 & #ee 94 diamet]1 ( alum9ium plate #jb 94 ?ick1 #c_/h 94 by #a_/h 94 rivet+ /rips 7 insuffici5t to make tight jo9ts2 x weigh$ #bf oz41 & at #hj lb4 wat] pressure "o ( ! ends blew out1 ! fracture occurr+ at ! b5d ( ! flange1 & n along ! l9e ( rivets4 ,! receiv] :i* 0 successful be+ app>5tly a t9-iron "o2 /eel tub+ 0 n to be _h at t date 9 ,sydney4 ,) a receiv] ( ?is "*1 & ! eng9e ref]r$ to above1 a flight ( #cdc ft4 0 obta9$1 ?is flight be+ ! be/4 7,! models con/ruct$ by him 7 n on ! a]oplane1 b orni?opt]e1 or w+-flapp+ pr9ciple47 ,! "t ( flight 0 #bc seconds1 ) #ed d\ble vibrations ( ! eng9es4 ,! effici5cy ( ?is motor 0 e/imat$ to be #bi p] c5t4 #bj4 ,by us+ compress$ air1 & heat+ x 9 its passage to ! cyl9d]1 f> great] effici5cy c be obta9$4 ,/eel cyl9d]s c be obta9$ conta9+ air "u ! enorm\s pressure ( #abj atmosph]es4#ai ,?is is practically liquid air4 ,a #bj-;ft4 cyl9d] weighs empty #bc lb4 ,! small] ! cyl9d] ! less ! proportionate pressure t x w /&2 & suppos+ a small /eel cyl9d]1 produc$ ( suitable =m & weight1 & capable ( )/&+ ) safety a pressure ( f #cjj to #fjj lb4 p] sq4 941 or f #bj to #dj atmosph]es4 ,! mo/ economical way ( work+ w\ld be to admit ! air f ! res]voir directly to ! motor cyl9d]s2 b ?is w\ld mean a v great range 9 ! initial work+ pressure1 entail+ n-to-be-?\ght-( weight 9 ! =m ( multi-cyl9d] comp\nd eng9es1 v>iable expansion ge>1 etc4 #ba4 ,?is means rel9qui%+ ! advantages ( ! high initial pressure1 & ! pass+ ( ! air ?r\gh a r$uc+ valve1 :]eby a con/ant pressure1 say1 ( #ij to #aej1 accord+ to circum/ances1 c\ld be ma9ta9$4 ,by a v>iation 9 ! ratio ( expansion ! air c\ld be work$ d[n to1 say1 #cj lb4 ,! initial loss entail$ by ! use ( a r$uc+ valve may be 9 a great measure re/or$ by heat+ ! air be=e us+ x 9 ! motor cyl9d]s2 by heat+ x to a temp]ature ( only #cbj;,f41 by means ( a suitable burn]1 ! volume ( air is increas$ by "o half1 ! consumption be+ r$uc$ 9 ! same proportion2 ! consumption ( air us$ 9 ?is way be+ #bd lb4 p] indicat$ horse-p[] p] h\r4 ,b ?is means extra weight 9 ! =m ( fuel & burn]s1 & :at we ga9 9 "o way we lose 9 ano!r4 ,x is1 ( c\rse1 desirable t ! motor %\ld "w at z l[ a pressure z possible1 s9ce z ! /ore ( air is us$ up ! pressure 9 ! res]voir falls1 until x rea*es a limit bel[ :i* x _c usefully be employ$4 ,! air !n rema9+ is dead & useless1 add+ only to ! weight ( ! a]oplane4 #bb4 ,f calculations made by ! writ] ! entire weight ( a compress$-air model motor plant w\ld be at lea/ "o-?ird ! weight ( ! a]oplane1 & on a small scale probably "o-half1 & _c !re=e hold comp>ison ) ! /eam eng9e discuss$ 9 ! next p>agraph4 ,9 conclud+ ^! rem>ks on compress$-air motors1 ,i d n wi% to dissuade anyone f try+ ?is =m ( motor2 b !y mu/ n emb>k on exp]im5ts ) ! idea t any?+ useful or any?+ sup]ior to results obta9$ ) inf9itely less exp5se by means ( rubb] c be br\ght to pass ) a bicycle pump1 a bit ( magnalium tube1 & #fj lb4 pressure4 #bb;,a4 ,9 ,tat9's air-compress$ motor ! res]voir weigh$ #gjj grammes1 & _h a capacity ( #h litres4 ,x 0 te/$ to )/& a pressure ( #bj atmosph]es1 b 0 work$ only up to sev54 ,! little eng9e atta*$ !reto weigh$ #cjj grammes1 & develop$ a motive p[] ( #b kilogram-metres p] second 7see *4 iii474 #bc4 ,/eam-,driv5 ,motors4--,sev]al successful /eam-eng9$ model a]oplanes h be5 con/ruct$1 ! mo/ fam\s be+ ^? ( ,pr(essor ,langley4 ,hav+ con/ruct$ ov] #cj modifications ( rubb]-driv5 models1 & exp]im5t$ ) compress$ air1 c>bonic-acid gas1 electricity1 & o!r me?ods ( obta9+ en]gy1 he f9ally settl$ ^u ! /eam eng9e 7! petrol motor 0 n available at t "t1 #ahic74 ,aft] _m mon?s' "w x 0 f\nd t ! weight c\ld n be r$uc$ bel[ #dj lb41 :il/ ! eng9e w\ld only develop ,h4,p41 & f9ally ! model 0 condemn$4 ,a second app>atus to be work$ by compress$ air 0 tri$1 b ! p[] prov$ insuffici5t4 ,!n came ano!r ) a c>bonic-acid gas eng9e4 ,!n o!rs ) v>i\s applications ( electricity & gas1 etc41 b ! /eam eng9e 0 f\nd mo/ suitable2 yet x seem$ to become m & m d\btful :e!r x c\ld ev] be made suffici5tly light1 & :e!r ! desir$ end c\ld be atta9$ at all4 ,! *ief ob/acle prov$ n to be ) ! eng9es1 :i* 7 made surpris+ly light aft] suffici5t exp]im5t4 ,! great difficulty 0 to make a boil] ( almo/ no weight :i* w\ld give /eam en\gh4 #bd4 ,at la/ a satisfactory boil] & eng9e 7 produc$4 ,! eng9e 0 ( #a to #a ,h4,p41 total weight 7includ+ mov+ p>ts7 #bf oz4 ,! cyl9d]s1 two 9 numb]1 _h ea* a diamet] ( #a 941 & pi/on /roke #b 94 ,! boil]1 ) its firegrate1 weigh$ a little ov] #e lb4 ,x consi/$ ( a cont9u\s helix ( copp] tub+1 #c_/h 94 ext]nal diamet]1 ! diamet] ( ! coil be+ #c 94 altoge!r4 ,?r\gh ! c5tre ( ?is 0 driv5 ! bla/ f an lopile1 a modification ( ! naph?a bl[-tor* us$ by plumb]s1 ! flame ( :i* is ab\t #bjjj ,f4#bj ,! pressure ( /eam issu+ into ! eng9es v>i$ f #ajj to #aej lb4 p] sq4 942 #d lb4 weight ( wat] & ab\t #aj oz4 ( naph?a c\ld be c>ri$4 ,! boil] evaporat$ #a lb4 ( wat] p] m9ute4 ,! tw9 propell]s1 #ci 94 9 diam41 pit* #a1 revolv$ f #hjj to #ajjj a m9ute4 ,! entire a]oplane 0 #ae ft4 9 l5g?1 ! a](oils f tip to tip ab\t #ad ft41 & ! total weight slightly less ?an #cj lb41 ( :i* "o-f\r? 0 conta9$ 9 ! ma*9]y4 ,its flight 0 a little ov] half a mile 9 l5g?1 & ( #a m9utes' duration4 ,ano!r model flew = ab\t ?ree-qu>t]s ( a mile1 at a rate ( ab\t #cj miles an h\r4 ,x w be not$ t eng9e1 g5]ator1 etc41 "w out at ab\t #g lb4 p] ,h4,p4 ,consid]able advance has be5 made 9 ! con/ruction ( light & p[]ful model /eam eng9es s9ce ,langley's "t1 *iefly 9 connexion ) model hydroplanes1 & a pressure ( f #ejj to #fjj lb4 p] sq4 94 has be5 employ$2 ! /eam turb9e has be5 br\ght to a high /ate ( p]fection1 & x is n[ possible to make a model ,de ,laval turb9e ( consid]able p[] weigh+ almo/ next to no?+1#ba ! real tr\ble1 9 fact ! only "o1 be+ ! /eam g5]ator4 ,an economization ( weight means a wa/e ( /eam1 ( :i* models c easily sp5d _! only weight 9 five m9utes4 #be4 ,"o way to economize )\t increas$ weight 9 ! %ape ( a cond5s] is to use _s 7me?ylat$ _s1 = in/ance7 = bo? fuel & boil]1 & cause ! exhau/ f ! eng9es to be eject$ on to ! burn+ _s1 :]e x itself s]ves z fuel4 ,by us+ _s1 or "s v volatile hydroc>bon1 in/ead ( wat]1 we h a fur!r advantage f ! fact t su* vaporize at a mu* l[] temp]ature ?an wat]4 #bf4 ,:5 exp]im5t+ ) an eng9e ( ! turb9e type we mu/ use a propell] ( small diamet] & pit*1 ow+ to ! v high velocity at :i* su* eng9es run4 ,anyone1 h[ev]1 :o is n an exp]t on su* matt]s w\ld d well to leave su* motors alone1 z ! v highe/ te*nical skill1 comb9$ ) _m prelim9>y disappo9tm5ts & trials1 are sure to be enc\nt]$ be=e success is atta9$4 #bg4 ,& ! small] ! model ! m difficult ! problem--halve y\r a]oplane1 & y\r difficulties increase any?+ f f\rfold to t5fold4 ,! boil] w\ld 9 any case be ( ! fla% type ( ei!r copp] or /eel tub+ 7! =m] = safety71 ) a magnalium conta9] = ! _s1 & a work+ pressure ( f #aej to #bjj lb4 p] sq4 94 ,any?+ less ?an ?is w\ld n be wor? consid]ation4 #bh4 ,"s t5 mon?s aft] ,pr(essor ,langley's successful model flights 7#ahif71 exp]im5ts 7 made 9 ,france at ,c>qu5ez1 ne> ,t\lon4 ,! total weight ( ! model a]oplane 9 ?is case 0 #gj lb42 ! eng9e p[] a little m ?an #a ,h4,p4 ,tw9 screws 7 us$--"o 9 front & "o beh9d4 ,! maximum velocity obta9$ 0 #dj miles p] h\r2 b ! l5g? ( run only #aed y>ds1 & duration ( flight only a few seconds4 ,?is result comp>es v poorly ) ,langley's di/ance 7( be/ flight71 ne>ly "o mile1 duration #a m94 #de sec4 ,! maximum velocity 0 great]--#cj to #dj miles p] h\r4 ,! total bread? ( ?is l>ge model 0 r m ?an #f metres1 & ! surface a little m ?an #h sq4 metres4 #bi4 ,petrol ,motors4--,"h x w\ld appe> at fir/ ?\ght is ! true solution ( ! problem ( ! model a]oplane motor4 ,su* a motor has solv$ ! problem ( a]ial locomotion1 z ! /eam eng9e solv$ t ( t]re/rial & m>9e travel1 bo? full siz$ & model2 & if 9 ! case ( full siz$ ma*9es1 !n :y n models4 ,illu/ration3 ,,fig4 #ah4--,,mr4 ,,/ang]',s ,,model ,,9 ,,full ,,flight4 ,illu/ration3 ,,fig4 #ai4--,,mr4 ,,/ang]',s ,,petrol-,,driv5 ,,model ,,a]oplane4 7,illu/rations by p]mission f electros suppli$ by ! ,a]o47 #cj4 ,! exact size ( ! smalle/ work+ model /eam eng9e t has be5 made ,i d n "k1#bb b x is or c\ld be surpris+ly small2 n s ! petrol motor--n "o1 t is1 t w\ld "w4 ,! numb] ( petrol motor-driv5 model a]oplanes t h actually fl[n is v small4 ,p]sonally ,i only "k ( "o1 viz41 ,mr4 ,d4 ,/ang]'s1 exhibit$ at ! a]o exhibition at ! ,agricultural ,hall 9 #aijh4 ,illu/ration3 ,,fig4 #bj4--,,mr4 ,,/ang]',s ,,model ,,petrol ,,eng9e4 ,illu/ration3 ,,fig4 #ba4--,,mr4 ,,/ang]',s ,,model ,,petrol ,,eng9e4 ,9 ,fig4 #ba ! motor is 9 position on ! a]oplane4 ,note small c>burettor4 ,9 ,fig4 #bj an idea ( ! size ( eng9e may be ga!r$ by comp>+ x ) ! ord9>y sp>k+-plug se5 by ! side1 :il/ to ! left ( ?is is "o ( ! special plugs us$ on ?is motor4 7,illu/rations by p]mission f electros suppli$ by ! ,a]o47 #ca4 ,! foll[+ are ! *ief p>ticul>s ( ?is int]e/+ ma*9e3--,! eng9e is a f\r-cyl9d] "o1 & weighs 7complete ) d\ble c>burett] & petrol tank7 #e lb41 & develops #a ,h4,p4 at #acjj revolutions p] m9ute4 ,illu/ration3 ,,fig4 #bb4--,,"o-,,cyl9d] ,,petrol ,,motor4 7,electro f ,messrs4 ,a4,w4 ,gamage's ,aviation ,catalogue47 ,! propell]1 #bi 94 9 diam4 & #cf 94 9 pit*1 gives a /atic ?ru/ ( ab\t #g lb4 ,! ma*9e has a spread ( #h ft4 #b 941 & is #f ft4 #aj 94 9 l5g?4 ,total weight #ba lb4 ,rises f ! gr\nd :5 a spe$ ( ab\t #af miles an h\r is atta9$4 ,a clockwork arrangem5t automatically /ops ! eng9e4 ,! eng9e air-cool$4 ,! cyl9d] ( /eel1 ca/-iron heads1 alum9ium crank-case1 d\ble float fe$ c>burett]1 ignition by s+le coil & di/ributor4 ,! a]oplane be+ #g ft4 #f 94 long1 & hav+ a span #h ft4 #cb4 ,"o-cyl9d] ,petrol ,motors4--,s f> z ! writ] is aw>e no success has z yet att5d$ ! use ( a s+le-cyl9d] petrol motor on a model a]oplane4 ,und\bt$ly ! vibration is excessive2 b ?is %\ld n be an insup]able difficulty4 ,x is true x is heavi] 9 proportion ?an a two-cyl9d] "o1 & n s effici5t2 & s f> has n prov$ successful4 ,! "q ( vibration on a model a]oplane is "o ( consid]able importance4 ,a badly balanc$ propell] ev5 w s]i\sly int]f]e ) & (t5 greatly curtail ! l5g? ( flight4 #cc4 ,electric ,motors4--,no attempt %\ld on any acc\nt be made to use electric motors = model a]oplanes4 ,!y are altoge!r too heavy1 ap>t ev5 f ! accumulator or s\rce ( electric en]gy1 = ! p[] d]ivable f !m4 ,to take an extreme case1 & suppos+ we use a #b-oz4 electric motor capable ( driv+ a propell] giv+ a /atic ?ru/ ( #c oz41#bc on weigh+ "o ( ! smalle/ size accumulators )\t case1 etc41 ,i f9d its weight is #d oz4 ,"o w\ld1 ( c\rse1 be ( no use2 at lea/ ?ree w\ld be requir$1 & !y w\ld require practically %ort circuit+ to give suffici5t amp]age 7runn+ !m d[n1 t is1 9 "s #aj to #ae seconds74 ,total weight1 #a lb4 ne>ly4 ,n[ f a p\nd weight ( rubb] "o c\ld obta9 a ?ru/ ( p\nds1 n ounces4 ,= scale models n int5d$ = actual flight1 ( c\rse1 electric motors h _! uses4 ,,footnotes3 #ab ,also !re is no necessity = ge>+4 #ac ,9 8 late/ models ! writ] uses /r&s ev5 ?ree times & n twice z long1 viz4 f\rte5 /r&s #dc 94 long4 #ad ,?is ref]s to #a_/af 94 squ>e section$ rubb]4 #ae ,( uni=m bread? & ?ickness4 #af ,9 practice ,i f9d n q s high a proportion z ?is is always necess>y4 #ag ,/eel p9ion wire is v suitable4 #ah ,see ,app5dix4 #ai ,z high a pressure z #bej atmosph]es has be5 us$4 #bj ,!re 0 a special pump keep+ ! wat] circulat+ rapidly ?r\gh ! boil]1 ! int5se heat conv]t+ "s ( x into /eam z x fl[$4 ,! mak+ ( ?is boil] alone consum$ mon?s ( "w2 ! entire ma*9e tak+ a ye> to con/ruct1 ) ! be/ me*anical help available4 #ba ,model ,/eam ,turb9es4 ,model ,eng9e] ,s]ies1 ,no4 #ac1 price #f;d4 #bb ,see ,introduction1 note to #a4 #bc ,! voltage1 etc41 is n /at$4 ,,*apt] ,v4 ,,propell]s ,,or ,,screws4 #a4 ,! design & con/ruction ( propell]s1 m especially ! =m]1 is )\t d\bt "o ( ! mo/ difficult p>ts ( model a]oplan+4 ,) ela/ic or spr+ driv5 models ! problem is m complicat$ ?an = models driv5 by petrol or "s vaporiz$ =m ( liquid fuel2 & less reliable in=mation is to h&4 ,! problem ( weight1 un=tunately1 is ( prim>y importance4 ,we w deal ) ^! po9ts 9 due c\rse2 to beg9 ) let u take3-- ,,! ,,position ,,( ,,! ,,propell]4 ,9 model a]oplanes ! propell] is usually situat$ ei!r 9 front or 9 ! re> ( ! model2 9 ! =m] case x is call$ a ,,tractor ,,screw1 i4e41 x pulls in/ead ( pu%es4 ,z to ! m]its ( ! two sy/ems ) respect to ! tractor1 !re is1 we "k1 9 ! case ( models mov+ ?r\gh wat] a di/9ct advantage 9 plac+ ! propell] beh9d1 & us+ a pu%+ or propulsive action1 on acc\nt ( ! frictional wake creat$ beh9d ! boat1 & :i* causes ! wat] to fl[ aft] ! vessel1 b at a less] velocity4 ,9 plac+ ! propell] beh9d1 we place x 9 su* a position z to act ^u & make use ( ?is ph5om5on1 ! effect ( ! propell] be+ to br+ ?is foll[+ wake to re/4 ,!oretically a boat1 model or o!rwise1 c be propell$ ) less horse-p[] ?an x c be t[$4 ,b ) respect to a]oplanes1 ap>t altoge!r f ! diff]5ce ( m$ium1 !re is at pres5t a v consid]able diff]5ce ( =m1 an a]oplane1 model or o!rwise1 be>+ at pres5t b little resemblance to ! hull ( a boat4 ,und\bt$ly !re is a frictional wake 9 ! case ( a]oplanes1 possibly q z mu* 9 proportion z 9 ! case ( a boat1 all[+ = diff]5ce ( m$ium4 ,admitt+1 !n1 t ?is wake does exi/1 x foll[s t a propulsive screw is bett] ?an a tractor4 ,9 a matt] ( ?is k9d con/ructional consid]ations1 or ease ( laun*+1 & ability to l& )\t damage1 mu/ be giv5 due weight4 ,9 ! case ( model a]oplanes con/ructional details incl9e ! balance nei!r "o way nor ! o!r2 b ease 9 laun*+ & ability to l& )\t damage weigh ! balance d[n mo/ decid$ly 9 fav\r ( a driv+ or propulsive screw4 ,9 ! case ( full-siz$ monoplanes con/ructional details _h mo/ to d ) ! use ( tractors2 b monoplanes are n[ be+ built ) propulsive screws4#bd ,9 ! case ( models1 n models ( full-siz$ ma*9es1 b actual model fly]s1 ! writ] consid]s propulsive screws mu* ! be/4#be ,9 no case %\ld ! propell] be plac$ 9 ! c5tre ( ! model1 or 9 su* a position z to %ort5 ! /r&s ( ! ela/ic motor1 if good flights are desir$4 ,9 ! case ( petrol or simil> driv5 models ! position ( ! propell] c be safely copi$ f actual well-recognis$ & successful full-siz$ ma*9es4 #b4 ,! ,numb] ( ,blades4--,!oretically ! numb] ( blades does n ent] into consid]ation4 ,! mass ( air dealt ) by ! propell] is repres5t$ by a cyl9d] ( indef9ite l5g?1 ^: diamet] is ! same z t ( ! screw1 & ! rate at :i* ?is cyl9d] is project$ to ! re> dep5ds !oretically ^u ! pit* & revolutions 7p] m9ute1 say7 ( ! propell] & n ! numb] ( blades4 ,!oretically "o blade 7helix incomplete7 w\ld be suffici5t1 b su* a screw w\ld n balance1 & balance is ( prim>y importance2 ! m9imum numb] ( blades :i* c be us$ is !re=e two4 ,9 m>9e models ?ree blades are consid]$ be/1 z giv+ a bett] balance4 ,9 ! case ( _! a]ial prototypes ! "q ( weight has aga9 to be consid]$1 & two blades is practically ! inv>iable cu/om4#bf ,"h1 aga91 con/ructional consid]ations aga9 come to ! =e1 & 9 ! case ( wood5 propell]s "o ( two blades is ( f> m easy con/ruction ?an "o ( ?ree4 ,by increas+ ! numb] ( blades ! ?ru/ is1 ( c\rse1 m ev5ly di/ribut$ ov] a l>g] area1 b ! weight is consid]ably increas$1 & 9 models a great] advantage is ga9$ by keep+ d[n ! weight ?an might foll[ f ! use ( m blades4 #c4 ,fan v]sus ,propell]4--,x mu/ always be mo/ c>efully borne 9 m9d t a fan 7v5tilat+7 & a propell] are n ! same ?+4 ,because _m blades are f\nd 9 practice to be effici5t 9 ! case ( ! =m]1 x is q wrong to assume t ! same conclusion holds 9 ! case ( ! latt]4 ,by increas+ ! numb] ( blades ! sk9 friction due to ! resi/ance t has to be ov]come 9 rotat+ ! propell] ?r\gh ! air is add$ to4 ,moreov] a fan is /ation>y1 :il/ a propell] is con/antly advanc+ z well z rotat+ ?r\gh ! air4 ,! action ( a fan bl[] is to move a small quantity ( air at a high velocity2 :]eas ! action ( a propell] is1 or %\ld be1 to move a l>ge quantity ( air at a small velocity1 = ! function ( a screw is to create ?ru/4 ,op]at+ on a yield+ fluid m$ium ?is ?ru/ w evid5tly be 9 proportion to ! mass ( fluid mov$1 & also to ! velocity at :i* x is put 9 motion4 ,b ! p[] consum$ 9 putt+ ?is mass ( fluid 9 motion is proportional to ! mass & to ! squ>e ( ! velocity at :i* x moves4 ,f ?is x foll[s1 z /at$ above1 t 9 ord] to obta9 a giv5 ?ru/ ) ! lea/ loss ( p[]1 ! mass ( fluid act$ on %\ld be z l>ge z possible1 & ! velocity imp>t$ to x z little z possible4 ,a fan requires to be s design$ z to create a ?ru/ :5 /ation>y 7/atic ?ru/71 & a propell] :il/ mov+ ?r\gh ! air 7dynamic ?ru/74 #d4 ,! ,function ( a ,propell] is to produce dynamic ?ru/2 & ! great advantage ( ! use ( a propell] z a ?ru/+ or propulsive ag5t is t its surface is always active4 ,x has no dead po9ts1 & its motion is cont9u\s & n reciprocat+1 & x requires no special ma*9]y or mov+ p>ts 9 its con/ruction & op]ation4 #e4 ,! ,pit* ( a propell] or screw is ! l9e> di/ance a screw moves1 backw>ds or =w>ds1 9 "o complete revolution4 ,?is di/ance is purely a !oretical "o4 ,:51 = in/ance1 a screw is said to h a pit* ( #a ft41 or #ab 941 x means t ! model w\ld advance #a ft4 ?r\gh ! air = ea* revolution ( ! screw1 provid$ t ! propell] blade 7 m\nt$ 9 solid guides1 l a nut on a bolt ) "o ?read p] foot4 ,9 a yield+ fluid su* z wat] or air x does n practically advance ?is di/ance1 & h5ce occurs :at is kn[n z-- #f4 ,slip1 :i* may be def9$ z ! di/ance :i* ought to be trav]s$1 b :i* is lo/ ?r\gh imp]fections 9 ! propell+ me*anism2 or x may be consid]$ z p[] :i* %\ld h be5 us$ 9 driv+ ! model =w>d4 ,9 ! case ( a locomotive runn+ on dry rails no?+ is lo/ 9 slip1 !re be+ none4 ,9 ! case ( a /eam] moor$ & h] eng9es set go+1 or ( an a]oplane held back prior to />t+1 all ! p[] is us$ 9 slip1 i4e4 9 putt+ ! fluid 9 motion1 & none is us$ 9 propulsion4 ,suppos+ ! propell] on our model has a pit* ( #a ft41 & we give ! ela/ic motor #ajj turns1 !oretically ! model %\ld travel #ajj ft4 9 calm air be=e ! propell] is run d[n2 no propell] yet design$ w d ?is4 ,suppos+ ! actual l5g? #gg ft41 #bc p] c5t4 has be5 lo/ 9 slip4 ,= ?is to be actually correct ! propell] mu/ /op at ! precise in/ant :5 ! ma*9e comes to gr\nd4 ,tak+ slip into acc\nt1 !n-- ,! spe$ ( ! model 9 feet p] m9ute pit* 79 feet7 revolutions p] m9ute -- slip 7feet p] m9ute74 ,?is slip wants to be made small--j h[ small is n yet kn[n4 ,if made too small !n ! propell] w n be s effici5t1 or1 at any rate1 su* is ! conclusion come to 9 m>9e propulsion1 :]e x is f\nd = ! mo/ economical results to be obta9$ t ! slip %\ld be f #aj to #bj p] c5t4 ,9 ! case ( a]ial propell]s a slip ( #be p] c5t4 is q good1 #dj p] c5t4 bad2 & !re are c]ta9 reasons = assum+ t possibly ab\t #ae p] c5t4 may be ! be/4 #g4 ,x is true t slip repres5ts en]gy lo/2 b "s slip is ess5tial1 because )\t slip !re c\ld be no ?ru/1 ?is same ?ru/ be+ d]iv$ f ! reaction ( ! volume ( air driv5 backw>ds4 ,! ?ru/ is equal to-- ,weight ( mass ( air act$ on p] second slip velocity 9 feet p] second4 ,9 ! case ( an a]oplane advanc+ ?r\gh ! air x might be ?\ght t ! ?ru/ w\ld be less4 ,sir ,hiram ,maxim f\nd1 h[ev]1 z ! result ( 8 exp]im5ts t ! ?ru/ ) a propell] travell+ ?r\gh ! air at a velocity ( #dj miles an h\r 0 ! same z :5 /ation>y1 ! r4p4m4 rema9+ con/ant ?r\gh\t4 ,! explanation is t :5 travell+ ! propell] is cont9ually advanc+ on to undi/urb$ air1 ! slip velocity is r$uc$1 b ! undi/urb$ air is equival5t to act+ ^u a great] mass ( air4 #h4 ,pit* ,coeffici5t or ,pit* ,ratio4--,if we divide ! pit* ( a screw by its diamet] we obta9 :at is kn[n z pit* coeffici5t or ratio4 ,! mean value ( eighte5 pit* coeffici5ts ( well-kn[n full-siz$ ma*9es works out at #jfb1 :i*1 z x s happ5s1 is exactly ! same z ! case ( ! ,f>man ma*9e propell] consid]$ alone1 ?is ratio v>y+ f #jd to #ab2 9 ! case ( ! ,wright's ma*9e x is 7probably7 #a4 ,! effici5cy ( _! propell] is admitt$ on all h&s4 ,_! propell] is1 ( c\rse1 a sl[-spe$ propell]1 #dej r4p4m4 ,! "o on ! ,blriot monoplane 7,blriot ,,xi47 pit* ratio #jd1 r4p4m4 #acej4 ,9 m>9e propulsion ! pit* ratio is g5]ally #ac = a sl[-spe$ propell]1 decreas+ to #ji = a high-spe$ "o4 ,9 ! case ( rubb]-driv5 model a]oplanes ! pit* ratio is (t5 c>ri$ mu* high]1 ev5 to ov] #c4 ,mr4 ,t4,w4,k4 ,cl>ke recomm5ds a pit* angle ( #de1 or less1 at ! tips1 & a pit* ratio ( #c-a_/g 7) an angle ( #de74 ,)9 limits ! high] ! pit* ratio ! bett] ! effici5cy4 ,! high] ! pit* ratio ! sl[] may be ! rate ( revolution4 ,n[ 9 a rubb] motor we d n want ! rubb] to untwi/ 7run out7 too quickly2 ) too f9e a pit* ! propell] races1 or does some?+ rem>kably l x4 ,x c]ta9ly revolves ) an abnormally high p]c5tage ( slip4 ,& = effici5cy x is c]ta9ly desirable to pu% ?is ratio to its limit2 b !re is also ! "q ( ! #i4 ,diamet]4--,! diamet] 7says ,mr4 ,t4,w4,k4 ,cl>ke7 %\ld be equal to "o-qu>t] ! span ( ! ma*9e4 ,if we increase ! diamet] we %all decrease ! pit* ratio4 ,f exp]im5ts :i* ! writ] has made he pref]s a l[] pit* ratio & increas$ diamet]1 viz4 a pit* ratio ( #ae1 & a diamet] ( "o-?ird to ev5 "o-half ! span1 or ev5 m4#bg ,c]ta9ly n less ?an "o-?ird4 ,"s model mak]s indulge 9 a l>ge pit* ratio1 angle1 diamet]1 & blade area z well1 b su* a c\rse is n to be recomm5d$4 #aj4 ,!oretical ,pit*4--,!oretically ! pit* 7f boss to tip7 %\ld at all po9ts be ! same2 ! boss or c5tre ( ! blade at "r angles to ! plane ( rotation1 & ! angle decreas+ z "o approa*es ! tips4 ,?is is obvi\s :5 "o consid]s t ! :ole blade has to move =w>d ! same am\nt4 ,9 ! diagrams ,figs4 #bc & #bd ! tip ,a ( ! propell] travels a di/ance #b pi ,r e revolution4 ,at a po9t ,d on ! blade1 di/ant r f ! c5tre1 ! di/ance is #b pi r4 ,9 bo? in/ances ! two po9ts mu/ advance a di/ance equal to ! pit*1 i4e4 ! di/ance repres5t$ by ,p ,o4 ,illu/ration3 ,,fig4 #bc4 ,illu/ration3 ,,fig4 #bd4 ,a ,o #b pi ,r2 ,d ,o #b pi r4 ,a w move along ,a ,p1 ,b along ,b ,p1 & s on4 ,! angles at ! po9ts ,a1 ,b1 ,c 444 7,fig4 #bd71 %[+ ! angles at :i* ! correspond+ p>ts ( ! blade at ,a1 ,b1 ,c 444 9 ,fig4 #bc mu/ be set 9 ord] t a uni=m pit* may be obta9$4 #aa4 ,if ! pit* be n uni=m !n !re w be "s portions ( ! blade :i* w drag ?r\gh ! air in/ead ( af=d+ useful ?ru/1 & o!rs :i* w be do+ m ?an !y ought1 putt+ air 9 motion :i* _h bett] be left quiet4 ,?is uni=m total pit* = all p>ts ( ! propell] is 7z already /at$7 a decreas+ rate ( pit* f ! c5tre to ! edge4 ,) a total pit* ( #e ft41 & a radius ( #d ft41 & an angle at ! circumf]5ce ( #f1 !n ! angle ( pit* at a po9t midway betwe5 c5tre & circumf]5ce %\ld be #ab1 9 ord] t ! total pit* may be ! same at all p>ts4 #ab4 ,to ,asc]ta9 ! ,pit* ( a ,propell]4--,take any po9t on "o ( ! blades1 & c>efully measure ! incl9ation ( ! blade at t po9t to ! plane ( rotation4 ,if ! angle s =m$ be ab\t #ai 7#aide71bh i4e41 #a 9 #c1 & ! po9t #e 94 f ! c5tre1 !n e revolution ?is po9t w travel a di/ance #b pi r #b #bb_/g #e #cacd4 ,n[ s9ce ! incl9ation is #a 9 #c1bi ! propell] w travel =w>d !oretically "o-?ird ( ?is di/ance1 or #cadc_/c #ajdh #aj 94 approx4 ,simil>ly any o!r case may be dealt )4 ,if ! propell] h a uni=m con/ant angle in/ead ( a uni=m pit*1 !n ! pit* may be calculat$ at a po9t ab\t "o-?ird ! l5g? ( ! blade f ! tip4 #ac4 ,holl[-,fac$ ,blades4#cj--;,x mu/ always be c>efully borne 9 m9d t a propell] is no?+ m nor less ?an a p>ticul> =m ( a]oplane specially design$ to travel a helical pa?4 ,x %\ld1 !re=e1 be holl[ fac$ & p>take ( ! /ream l9e =m1 a condition n fulfill$ if ! face ( ! blade be flat--su* a surface cutt+ into ! air ) consid]able %ock1 & by no means creat+ z little undesirable motion 9 ! surr\nd+ m$ium z possible4 ,x mu/ n be =gott5 t a curv$ face blade has ( necessity an increas+ pit* f ! cutt+ to ! trail+ edge 7consid]+1 ( c\rse1 any p>ticul> section74 ,9 su* a case ! pit* is ! mean effective pit*4 #ad4 ,blade ,area4--,we h already ref]r$ to ! fact t ! function ( a propell] is to produce dynamic ?ru/--to drive ! a]oplane =w>d by driv+ ! air backw>ds4 ,at ! same "t x is mo/ desirable = effici5cy t ! air %\ld be set 9 motion z little z possible1 ?is be+ s mu* p[] wa/$2 to obta9 ! greate/ reaction or ?ru/ ! greate/ possible volume ( air %\ld be accel]at$ to ! smalle/ velocity4 ,9 m>9e eng9e]+ 9 sl[-spe$ propell]s 7:]e cavitation#ca does n come 97 n>r[ blades are usually us$4 ,9 high-spe$ m>9e propell]s 7:]e cavitation is liable to occur7 ! project$ area ( ! blades is sometimes z mu* z #jf ( ! total disk area4 ,9 ! case ( a]ial propell]s1 :]e cavitation does n occur1 or n unless ! velocity be a v high "o 7#aejj or m a m9ute71 n>r[ blades are ! be/4 ,exp]im5ts 9 m>9e propulsion also %[ t ! ?ru/ dep5ds m on ! disk area ?an on ! wid? ( ! blades4 ,all ! facts t5d to %[ t = effici5cy ! blades ( ! propell] %\ld be n>r[1 9 ord] t ! air may n be act$ on = too long a "t1 & s put too mu* 9 motion1 & ! blades be s sep>at$ t "o blade does n di/urb ! molecules ( air ^u :i* ! next foll[+ "o mu/ act4 ,bo? 9 ! case ( m>9e & a]ial propell]s multiplicity ( blades 7i4e4 increas$ blade area7 t5ds to ineffici5cy ( action1 ap>t altoge!r f ! "q ( weight & con/ructional difficulties4 ,! "q ( increas+ pit* 9 ! case ( holl[-fac$ blades1 consid]$ 9 ! la/ p>agraph1 has a v important be>+ on ! po9t we are consid]+4 ,to make a wide blade "u su* circum/ances w\ld be to soon obta9 an excessive angle4 ,9 ! case ( a flat blade ! same result holds1 because ! air has by ! contact ( its molecules ) ! initial m9imum wid? be5 already accel]at$ up to its f9al velocity1 & fur!r area is n only wa/$1 b inimical to good flights1 be+ our old bugbe> weight 9 excess4 ,requisite /r5g? & /iffness1 ( c\rse1 set a limit on ! f9al n>r[ness ( ! blades1 ap>t f o!r consid]ations4 #ae4 ,! velocity ) :i* ! propell] is rotat$ has also an important be>+ on ?is po9t2 b a high] spe$ ?an #ijj r4p4m4 does n appe> desirable1 & ev5 #gjj or less is g5]ally pref]able4#cb ,9 case ( tw9-screw propell]s1 ) an angle at ! tips ( #dj to #de1 z l[ a velocity ( #ejj or ev5 less w\ld be /ill bett]4#cc #af4 ,%r\d+4--,no improvem5t :atev] is obta9$ by ! use ( any k9d ( %r\d+ or r+ r\nd ! propell] tips1 or by corrugat+ ! surface ( ! propell]1 or by us+ cyl9drical or cone-%ap$ propell] *amb] or any k9d ( air guide ei!r be=e or aft] ! propell]2 all[ x to revolve 9 z free an air-fe$ z possible1 ! air does n fly (f "u c5trifugal =ce1 b is p[]fully suck$ inw>ds 9 a well-design$ propell]4 ,illu/ration3 ,,fig4 #be4 ,a ,,tube ,,( ,,air4 ,illu/ration3 ,,fig4 #bf4 ,a ,,cyl9d] ,,( ,,air4 #ag4 ,g5]al ,design4--,! propell] %\ld be s con/ruct$ z to act ^u a tube & n a cyl9d] ( air4 ,_m fly+ toys 7especially ! ,fr5* ones7 are con/ruct$ ) propell]s ( ! cyl9d] type4 ,ease ( manufacture & ! cont5tion t ^? portions ( ! blades adjac5t to ! boss d little "w1 & a slight sav+ 9 weight1 are argum5ts t c be urg$ 9 _! fav\r4 ,b all ! c5tral cut away "p (f]s resi/ance 9 ! l9e ( travel1 in/ead ( ex]t+ its proportionate propulsive p[]1 & _! effici5cy is affect$ by su* a practice4 #ah4 ,a good ,%ape = ! blades#cd is rectangul> ) r\nd$ corn]s2 ! radius ( ! circle = r\nd+ (f ! corn]s may be tak5 z ab\t "o-qu>t] ( ! wid? ( ! blade4 ,! %ape is n truly rectangul>1 = ! wid? ( ?is rectangul> at 7ne>7 ! boss %\ld be "o-half ! wid? at ! tip4 ,! ?ickness %\ld dim9i% uni=mly f ! boss to ! tip4 7,9 models ! ?ickness %\ld be z little z is consi/5t ) /r5g? to keep d[n ! weight74 ,! pit* uni=m & l>ge4 ,illu/ration3 ,,fig4 #bg4--,o ,t #a_/c ,o ,p4 #ai4 ,! ,blades1 two 9 numb]1 & holl[ fac$--! maximum concavity be+ "o-?ird ! di/ance f ! ent]+ to ! trail+ edge2 ! ratio ( ,a ,t to ,o ,p 7! wid?7 be+ #jjdh or #a 3 #ba1 ^! latt] consid]ations be+ f\nd$ on ! analogy betwe5 a propell] & ! a](oil surface4 7,if ! ?ickness be v>i$ f ! ent]+ to ! trail+ edge ! greate/ ?ickness %\ld be t[>ds ! =m]47 ,! convex surface ( ! propell] mu/ be tak5 into acc\nt1 9 fact1 x is no less important ?an ! concave1 & ! entire surface mu/ be giv5 a true /ream l9e =m4 ,illu/ration3 ,,fig4 #bh4 ,illu/ration3 ,,fig4 #bi4 ,if ! ent]+ & trail+ edge be n bo? /raight1 b "o be curv$ z 9 ,fig4 #bh1 !n ! /raight edge mu/ be made ! trail+ edge4 ,& if bo? be curv$ z 9 ,fig4 #bi1 !n ! concave edge mu/ be ! trail+ edge4 #ai4 ,propell] ,design4--,to design a propell]1 proce$ z foll[s4 ,suppose ! diamet] #ad 94 & ! pit* ?ree times ! diamet]1 i4e4 #eb 94 7,see ,fig4 #cj47 ,take "o-qu>t] scale1 say4 ,draw a c5tre l9e ,a ,b ( conv5i5t l5g?1 set ( half ! pit* #eb 94 -- scale #e 94 ,c - ,d4 ,draw l9es ?r\gh ,c & ,d at "r angles to ,c ,d4 ,) a radius equal to half ! diamet] 7i4e4 9 ?is case #a 947 ( ! propell]1 describe a semicircle ,e ,b ,f & complete ! p>allelogram ,f ,h ,g ,e4 ,divide ! semicircle into a numb] ( equal p>ts2 twelve is a conv5i5t numb] to take1 !n ea* division subt5ds an angle ( #ae at ! c5tre ,d4 ,divide "o ( ! sides ,e ,g into ! same numb] ( equal p>ts 7twelve7 z %[n4 ,?r\gh ^! po9ts draw l9es p>allel to ,f ,e or ,h ,g4 ,& ?r\gh ! twelve po9ts ( division on ! semicircle draw l9es p>allel to ,f ,h or ,e ,g z %[n4 ,! l9e drawn ?r\gh ! successive int]sections ( ^! l9es is ! pa? ( ! tip ( ! blade ?r\gh half a revolution1 viz4 ! l9e ,h ,s ,o ,t ,e4 ,s ,o ,t ,x gives ! angle at ! tip ( ! blades #dd4 ,let ! %ape ( ! blade be rectangul> ) r\nd$ corn]s1 & let ! bread? at ! tip be twice t at ! boss4 ,!n ! area 7neglect+ ! r\nd$ (f corn]s7 is #aj sq4 94 ,illu/ration3 ,,fig4 #cj4--,,propell] ,,design4 ,"o qu>t] scale4 ,diamet] #ad 94 ,pit* #eb 94 ,angle at tip #dd4 ,! area be+ t ( a rectangle #g 94 #a 94 #g sq4 94 plus area ( two triangles1 base 941 height #g 94 ,n[ area ( triangle half base height4 ,!re=e area ( bo? triangles 94 #g 94 #c sq4 94 ,n[ ! area ( ! disc swept out by ! propell] is pi_/#d 7diam47 7pi #bb_/g7 ,illu/ration3 ,,fig4 #ca4--,,propell] ,,design4 ,scale "o-eigh? = ,a ,b & ,b ,c2 b sections ( blade are full-siz$4 ,& if d ,a r ! disc area ratio we h 7d ,a r7 pi_/#d 7#ad7 area ( blade #aj1 :5ce d ,a r #jjg ab\t4 ,illu/ration3 ,,fig4 #cb4 ,illu/ration3 ,,fig4 #cc4 ,9 ,fig4 #ca set (f ,a ,b equal to ! pit* ( ! propell] 7#db 9471 "o-eigh? scale4 ,set (f ,b ,c at "r angles to ,a ,b & equal to pi diamet] #bb_/g #ad #dd 94 to scale #e 94 ,divide ,b ,c into a conv5i5t numb] ( equal p>ts 9 ! figure2 five only are tak51 ,d1 ,e1 ,f1 ,g1 ,h2 jo9 ,a ,d1 ,a ,e1 ,a ,f1 ,a ,g1 ,a ,h & produce !m2 m>k (f di/ances ,p ,o1 ,s ,r1 ,y ,t 444 equal to ! wid? ( ! blade at ^! po9ts 7,h ,p ,h ,o2 ,g ,s ,g ,r 4447 & sket* 9 ! sections ( blade z desir$4 ,9 ! figure ! greate/ concavity ( ! blade is suppos$ to be "o-?ird ! di/ances ,p ,o1 ,s ,r 444 f ,,ps4444 ,! concavity is some:at exagg]at$4 ,! angles ,a ,h ,b1 ,a ,g ,b1 ,a ,f ,b 444 repres5t ! pit* angle at ! po9ts ,h1 ,g1 ,f 444 ( ! blade4 ,simil>ly any o!r design may be dealt )2 9 a propell] ( #ad 94 diamet] ! diamet] ( ! boss %\ld n be m ?an #aj_/af 94 #bj4 ,exp]im5ts ) ,propell]s4--,! propell] design %[n 9 ,figs4 #cb & #cc1 due to ,mr4 ,g4 de ,havill&1#ce is "o v suitable = exp]im5tal purposes4 ,a s+le tube pass+ ?r\gh a ,t-%ap$ boss =ms ! arms4 ,on ! back ( ! metal blade are rivet$ f\r metallic clips2 ^! clips be+ tight5$ r\nd ! arm by c\nt]sunk screws 9 ! face ( ! blade4 ,! tube & clips1 etc41 are all conta9$ ) ! back cov]+ ( ! blade1 z %[n 9 ,fig4 #ce1 if desir$1 ! blade !n practically resembl+ a wood5 propell]4 ,! con/ruction1 x w be notic$1 all[s ( ! blade be+ set at any angle1 con/ant or o!rwise2 also ! pit* c be con/ant or v>iable z desir$1 & any %ape ( propell] c be fitt$4 ,! advantage ( be+ able to twi/ ! blade 7)9 limits7 on ! axis is "o n to be und]e/imat$ 9 exp]im5tal "w4 ,illu/ration3 ,,fig4 #cd4--,,! ,,au?or',s ,,propell] ,,te/+ ,,app>atus4 ,) a view to asc]ta9 "s practical & reliable data ) respect to ! dynamic1 or actual ?ru/ giv5 :5 mov+ ?r\gh free air at ! velocity ( actual travel1 ! au?or exp]im5t$ ) ! app>atus illu/rat$ 9 ,figs4 #cd & #ce1 :i* is s simple & obvi\s z to require sc>cely any explanation4 ,! wires 7 ( /eel1 l5g? n q #aej ft41 fitt$ ) wire /ra9]s = equalis+ t5sion1 & absolutely free f k9ks4 ,z %[n mo/ pla9ly 9 ,fig4 #ce1 !re 7 two p>allel wires suffici5tly f> ap>t = ! action ( "o propell] n to affect ! o!r4 ,call+ ^! two wires ,a & ,b1 & two propell]s x & y1 !n x is fir/ tri$ on ,a & y on ,b4 ,results c>efully not$4 ,illu/ration3 ,,fig4 #ce4--,,propell] ,,te/+4 ,%[+ di/ance sep>at+ ! two wires4 ,!n x is tri$ on ,b & y on ,a1 & ! results aga9 c>efully not$4 ,if ! results confirm "o ano!r1 ! p[] us$ 9 bo? cases be+ ! same1 well & good2 if n1 adju/m5ts1 etc41 are made 9 ! app>atus until satisfactory results are obta9$4 ,?is 0 done :5 ! propell]s rac$ "o aga9/ ! o!r4 ,at o!r times "o wire only 0 made use (1 & ! "t & di/ance trav]s$ 0 not$ 9 ea* case4 ,propell]s 7 driv5 ?r\gh smoke1 & ) silk ?reads ti$ to a light framework slightly l>g] ?an _! disc area circumf]5ce4 ,results ( great int]e/ 7 arriv$ at4 ,^! results h be5 assum$ 9 mu* t has be5 said 9 ! =ego+ p>agraphs4 ,illu/ration3 ,,fig4 #cf4--,,"o ,,gr\p ,,( ,,propell]s ,,te/$ ,,by ,,! ,,au?or4 ,briefly put1 ^! results %[$3-- #a4 ,! ineffici5cy ( a propell] ( ! fan bl[] or ( ! /atic ?ru/ type4 #b4 ,! advantage ( us+ propell]s hav+ holl[-fac$ blades & l>ge diamet]4 #c4 ,t diamet] 0 m useful ?an blade area1 i4e4 giv5 a c]ta9 quantity 7weight7 ( wood1 make a long ?9 blade & n a %ort] "o ( m blade area--blade area1 i4e41 z proportionate to its correspond+ disc area4 #d4 ,t ! propell] surface %\ld be ( true /ream-l9e =m4 #e4 ,t x %\ld act on a cyl9d] & n tubes ( air4 #f4 ,t a correctly design$ & proportion$ propell] 0 j z efficaci\s 9 a small size ( #i 94 to #bh 94 z a full-siz$ propell] on a full-siz$ ma*9e4 ,illu/ration3 ,,fig4 #cg4--;,,an ,,effici5t ,,propell]1 ,,b ,,r ,,heavy4 ,ball be>+s1 old & new4 ,note diff]5ce 9 sizes & weights4 ,propell]1 #ad 94 diam42 weight #cf grammes4 ,a propell] ( ! /atic-?ru/ type 01 ( c\rse1 fir/ (f1 sometimes #aj ft4 or #ab ft4 ahead1 or ev5 m2 b ! correctly design$ propell] gradually ga!r$ up spe$ & accel]ation1 j z ! o!r fell (f & lo/ x1 & f9ally ! dynamic f9i%$ along its correspond+ wire f> ahead ( ! /atic1 sometimes twice z f>1 sometimes six times4 ,freak propell]s 7 simply n 9 x4 ,illu/ration3 ,,fig4 #ch4--,,v5na ,,propell]4 ,a #bj p] c5t4 m effici5t propell] ?an t %[n 9 ,fig4 #da2 #ad p] c5t4 light]2 #f p] c5t4 bett] 9 dynamic ?ru/--#ad 94 diam42 weight #ca grammes4 ,metal propell]s ( con/ant angle1 z well z wood5 ones ( uni=m 7con/ant7 pit*1 7 te/$2 ! =m] gave good results1 b n s good z ! latt]4 ,! be/ angle ( pit* 7at ! tip7 0 f\nd to be f #bj to #cj4 ,9 all cases :5 ! slip 0 z l[ z #be p] c5t41 or ev5 some:at less1 ne>ly #bj p] c5t41 a di/9ct back curr5t ( air 0 giv5 out by ! screw4 ,?is slip /ream1 z x is caus$1 is absolutely necess>y = effici5cy4 #ba4 ,fabric-cov]$ screws did n give v effici5t results2 ! only po9t 9 _! use on model a]oplanes is _! extreme lightness4 ,two su* propell]s ( #f 94 diamet] c be made to weigh less ?an #a_/e oz4 ! pair2 b wood5 propell]s 7built-up pr9ciple7 h be5 made #e 94 diamet] & #a_/ab oz4 9 weight4 #bb4 ,fur!r exp]im5ts 7 made ) tw9 screws m\nt$ on model a]oplanes4 ,9 "o case two propell]s1 bo? turn+ 9 ! same direction1 7 m\nt$ 7)\t any comp5satory adju/m5t = torque7 on a model1 total weight #a lb4 ,diamet] ( ea* propell] #ad 942 angle ( blade at tip #be4 ,! result 0 sev]al good flights--! model 7see ,fig4 #di;c7 0 slightly un/eady across ! w9d1 t 0 all4 ,9 ano!r exp]im5t two propell]s ( same diamet]1 pit*1 etc41 b ( %ape simil> to ^? %[n 9 ,figs4 #bh & #bi1 7 tri$ z tw9 propell]s on ! same ma*9e4 ,! rubb] motors 7 ( equal weight & /r5g?4 ,! model describ$ circl$ to ! "r or left accord+ to ! position ( ! curv$-%ap$ propell]1 :e!r on ! left or "r h&1 !reby %[+ its sup]iority 9 dynamic ?ru/4 ,v>i\s alt]ations 7 made1 b always ) ! same result4 ,^! exp]im5ts h s9ce be5 confirm$1 & !re seems no d\bt t ! d\ble-curv$ %ap$ blade is sup]ior4 7,see ,fig4 #ci47 #bc4 ,! ,flem+-,williams ,propell]4--,a *apt] on propell]s w\ld sc>cely be complete )\t a ref]5ce to ! propell] us$ on a ma*9e claim+ a record ( ov] a qu>t] ( a mile4 ,?is =m ( propell]1 %[n 9 ! gr\p 9 ,fig4 #cf 7top "r h&71 0 f\nd by ! writ] to be extremely defici5t 9 dynamic ?ru/1 giv+ ! wor/ result ( any %[n !re4 ,illu/ration3 ,,fig4 #ci4--;,,curv$ ,,d\ble ,,propell]4 ,! mo/ effici5t type yet te/$ by ! writ]1 :5 ! blade is made holl[-fac$4 ,:5 giv5 to ! writ] to te/ x 0 flat-fac$ on "o side4 ,illu/ration3 ,,fig4 #dj4--,,! ,,flem+-,,williams ,,model4 ,x possesses l>ge blade area1 l>ge pit* angle--m ?an #de at ! tip--& l>ge diamet]4 ,^! d n comb9e to propell] effici5cy or to effici5t dynamic ?ru/2 b !y d1 ( c\rse1 comb9e to give ! propell] a v sl[ rotational velocity4 ,provid$ !y give suffici5t ?ru/ to cause ! model to move ?r\gh ! air at a velocity capable ( su/a9+ x1 a long flight may result1 n really ow+ to true effici5cy on ! "p ( ! propell]s1#cf b ow+ to ! *eck plac$ on _! revolutions p] m9ute by _! abnormal pit* angle1 etc4 ,! am\nt ( rubb] us$ is v great = a #aj oz4 model1 namely1 #cd /r&s ( #a_/af 94 squ>e rubb] to ea* propell]1 i4e4 #fh /r&s 9 all4 ,illu/ration3 ,,fig4 #da4--,,! ,,same ,,9 ,,flight4 7,reproduc$ by p]mission f ,! ,a]o47 ,on ! score ( effici5cy1 :5 x is desir$ to make a limit$ numb] ( turns give ! longe/ flight 7:i* is ! problem "o always has to face :5 us+ a rubb] motor7 x is bett] to make use ( an abnormal diamet]1 say1 m ?an half ! span1 & us+ a tip pit* angle ( #be1 ?an to make use ( an abnormal tip pit* #de & m1 & l>ge blade area4 ,9 a l>ge pit* angle s mu* en]gy is wa/$1 n 9 dynamic ?ru/1 b 9 transv]se upsett+ torque4 ,on no propell] out ( doz5s & doz5s t ,i h te/$ h ,i ev] f\nd a tip-pit* ( m ?an #ce give a good dynamic ?ru/2 & = l5g? ( flight velocity due to dynamic ?ru/ mu/ be giv5 due weight1 z well z ! duration ( runn+ d[n ( ! rubb] motor4 #bd4 ,( built up or c>v$ out & twi/$ wood5 propell]s1 ! =m] give ! bett] result2 ! latt] h an advantage1 h[ev]1 9 sometimes weigh+ less4 ,,footnotes3 #bd ,note4--,s9ce ! above 0 writt5 "s really rem>kable flights h be5 obta9$ ) a #a oz4 model hav+ two screws1 "o 9 front & ! o!r beh9d4 ,equally good flights h also be5 obta9$ ) ! two propell]s beh9d1 "o revolv+ 9 ! imm$iate re> ( ! o!r4 ,fly+1 ( c\rse1 ) ! w9d1 weight is ( p>am\nt importance 9 ^! little models1 & 9 bo? ^! cases ! s+le /ick c be made use (4 ,see also *4 iv41 #bh4 #be ,see also *4 viii41 #e4 #bf ,save 9 case ( "s models ) fabric-cov]$ propell]s4 ,"s dirigibles are n[ be+ fitt$ ) f\r-blad$ wood5 screws4 #bg ,vide ,app5dix4 #bh ,vide ,equival5t ,incl9ations--,table (4 #bi ,"o 9 #c or #jccc is ! s9e ( ! angle2 simil>ly if ! angle 7 #cj ! s9e w\ld be #je or 1 & ! !oretical di/ance travell$ "o-half4 #cj ,flat-,fac$ ,blades4--,if ! blade be n holl[-fac$--& we consid] ! screw z an incl9$ plane & apply ! ,du*em9 =mula to x--! velocity rema9+ ! same1 ! angle ( maximum ?ru/ is #ce4 ,exp]im5ts made ) su* screws confirm ?is4 #ca ,cavitation is :5 ! high spe$ ( ! screw causes x to c>ry r\nd a c]ta9 am\nt ( ! m$ium ) x1 s t ! blades /rike no undi/urb$1 or solid1 air at all1 ) a proportionate decrease 9 ?ru/4 #cb ,9 ! ,wright ma*9e r4p4m4 #dej2 9 ,blriot ,,xi4 r4p4m4 #acej4 #cc ,su* propell]s1 h[ev]1 require a consid]able am\nt ( rubb]4 #cd ,b see also #bb4 #ce ,flight1 ,m>* #aj1 #aiaj4 7,illu/ration reproduc$ by p]mission47 #cf ,accord+ to ! au?or's views on ! subject4 ,,*apt] ,,vi4 ,,! ,,"q ,,( ,,su/5tation ,,! ,,c5tre ,,( ,,pressure4 #a4 ,pass+ on n[ to ! /udy ( an a]oplane actually 9 ! air1 !re are two =ces act+ on x1 ! upw>d lift due to ! air 7i4e4 to ! movem5t ( ! a]oplane suppos$ to be cont9ually advanc+ on to fre%1 undi/urb$ virg9 air71 & ! =ce due to ! weight act+ v]tically d[nw>ds4 ,we c consid] ! resultant ( all ! upw>d su/a9+ =ces z act+ at a s+le po9t--t po9t is call$ ! ,c5tre ( ,pressure4 ,suppose ,a ,b a v]tical section ( a flat a](oil1 incl9$ at a small angle a to ! horizon ,c1 ! po9t ( application ( ! resultant upw>d 'lift1' ,d ! po9t ?r\gh :i* ! weight acts v]tically d[nw>ds4 ,omitt+ = ! mom5t ! action ( propulsion1 if ^! two =ces balance !re w be equilibrium2 b to d ?is !y mu/ pass ?r\gh ! same po9t1 b z ! angle ( incl9ation v>ies1 s does ! c5tre ( pressure1 & "s means mu/ be employ$ :]eby if ,c & ,d co9cide at a c]ta9 angle ! a]oplane w come back to ! correct angle ( balance if ! latt] be alt]$4 ,9 a model ! means mu/ be automatic4 ,automatic /ability dep5ds = its action ^u ! movem5t ( ! c5tre ( pressure :5 ! angle ( incid5ce v>ies4 ,:5 ! angle ( incid5ce increases ! c5tre ( pressure moves backw>ds t[>ds ! re> ( ! a](oil1 & vice v]sa4 ,let u take ! case :5 /eady flight is 9 progress & ,c & ,d are co9cid5t1 suppose ! velocity ( ! w9d sudd5ly to increase--increas$ lift+ effect is at once ! result1 & ! =e "p ( ! ma*9e rises1 i4e4 ! angle ( incid5ce increases & ! c5tre ( pressure moves back to "s po9t 9 ! re> ( ,c ,d4 ,! weight is n[ cle>ly try+ to pull ! nose ( ! a]oplane d[n1 & ! lift t5d+ to raise ! tail4 ,! result be+ an alt]ation ( ! angle ( incid5ce1 or angle ( attack z x is call$1 until x resumes its orig9al position ( equilibrium4 ,a drop 9 ! w9d causes exactly an opposite effect4 ,illu/ration3 ,,fig4 #db4 #b4 ,! dang] lies 9 oscillations be+ set up 9 ! l9e ( flight due to *anges 9 ! position ( ! c5tre ( pressure4 ,h5ce ! device ( an elevator or horizontal tail = ! purpose ( damp+ out su* oscillations4 #c4 ,b ! a](oil surface is n flat1 ow+ to ! increas$ lift giv5 by ar*$ surfaces1 & a mu* m complicat$ set ( ph5om5a !n takes place1 ! c5tre ( pressure mov+ =w>d until a c]ta9 critical angle ( incid5ce is rea*$1 & aft] ?is a rev]sal takes place1 ! c5tre ( pressure !n actually mov+ backw>ds4 ,! problem !n consi/s 9 asc]ta9+ ! mo/ effici5t a]ocurve to give ! greate/ lift ) ! lea/ drift1 &1 hav+ f\nd x1 to inve/igate aga9 exp]im5tally ! movem5ts ( ! c5tre ( pressure at v>y+ angles1 & especially to det]m9e at :at angle 7ab\t7 ?is rev]sal takes place4 ,illu/ration3 ,,fig4 #dc4 #d4 ,natural automatic /ability 7! only "o possible s f> z models are conc]n$7 necessitates p]man5t or a p]man5tly recurr+ co9cid5ce 7to co9 a phrase7 ( ! c5tre ( gravity & ! c5tre ( pressure3 ! =m] is1 ( c\rse1 totally unaffect$ by ! vag>ies ( ! latt]1 any %ift+ ( :i* produces a c\ple t5d+ to de/roy equilibrium4 #e4 ,z to ! be/ =m ( camb] 7= full siz$ ma*9e7 possibly m is kn[n on ?is po9t ?an on any o!r 9 ! :ole ( a]onautics4 ,9 ,figs4 #dd & #de are giv5 two v effici5t =ms ( camb]$ surfaces = models4 ,illu/ration3 ,,fig4 #dd4--;,,an ,,effici5t ,,=m ,,( ,,camb]4 ,b ,d ,maximum ,altitude4 ,a ,c ,*ord4 ,ratio ( ,b ,d3 ,a ,c 33 #a3ag4 ,a ,d #a_/c ( ,a ,c4 ,illu/ration3 ,,fig4 #de4--;,,ano!r ,,effici5t ,,=m4 ,ratio ( ,b ,d to ,a ,c #a to #ag4 ,,ad r m ?an ( ,a ,c4 ,! next "q1 aft] hav+ decid$ ! "q ( a]ocurve1 or curvature ( ! planes1 is at :at angle to set ! camb]$ surface to ! l9e ( flight4 ,?is br+s u to ! "q ( !-- #f4 ,dipp+ ,front ,edge4--,! lead+ or front edge is n tang5tial to ! l9e ( flight1 b to a relative upw>d w9d4 ,x is :at is kn[n z ! cyclic up-curr5t1 :i* exi/s 9 ! neighb\rhood ( ! ent]+ edge4 ,n[1 z we h /at$ be=e1 x is ( p>am\nt importance t ! a](oil %\ld receive ! air ) z little %ock z possible1 & s9ce ?is up-curr5t does really exi/ to d ?is1 x mu/ travel ?r\gh ! air ) a dipp+ front edge4 ,! relative w9d 7! only "o ) :i* we are conc]n$7 is !reby met tang5tially1 & z x moves onw>d ?r\gh ! air ! camb]$ surface 7or a]ocurve7 gradually trans=ms ?is upw>d tr5d into a d[nw>d wake1 & s9ce by ,newton's law1 ,action & reaction are equal & opposite1 we h an equal & opposite upw>d reaction4 ,we n[ "k t ! top 7or convex side7 ( ! camb]$ surface is practically almo/ z important z ! und]nea? or concave side 9 br++ ?is result ab\t4 ,! exact am\nt ( dipp+ edge1 & ! exact angle at :i* ! *ord ( ! a]ocurve1 or camb]$ surface1 %\ld be set to ! l9e ( flight--:e!r at a positive angle1 at no angle1 or at a negative angle--is "o be/ det]m9$ by exp]im5t on ! model 9 "q4 ,illu/ration3 ,,fig4 #df4 ,b if at any angle1 t angle ei!r way %\ld be a v small "o4 ,if y wi% to be v sci5tific y c give ! und]side ( ! front edge a negative angle ( #e to #g = ab\t "o-eigh? ( ! total l5g? ( ! section1 aft] t a positive angle1 gradually increas+ until y f9ally f9i% up at ! trail+ edge ) "o ( #d4 ,also1 ! =m ( camb]$ surface %\ld be a p>aboloid--n arc or arc ( circles4 ,! writ] does n recomm5d su* an angle1 b pref]s an attitude simil> to t adopt$ 9 ! ,wright ma*9e1 z 9 ,fig4 #dg4 #g4 ,ap>t f ! attitude ( ! a]ocurve3 ! greate/ dep? ( ! camb] %\ld be at "o-?ird ( ! l5g? ( ! section f ! front edge1 & ! total dep? measur$ f ! top surface to ! *ord at ?is po9t %\ld n be m ?an "o-sev5te5? ( ! l5g? ( section4 #h4 ,x is ! greate/ mi/ake 9 model a]oplanes to make ! camb] o!rwise ?an v slight 79 ! case ( surfac$ a](oils ! resi/ance is mu* increas$71 & a](oils ) any?+ b a v slight ar* are liable to be v un/able1 = ! a]ocurve has always a decid$ t5d5cy to foll[ its own curve4 ,illu/ration3 ,,fig4 #dg4--;,,attitude ,,( ,,wright ,,ma*9e4 ,! nature ( ! a]ocurve1 its area1 ! angle ( incl9ation ( its *ord to ! l9e ( flight1 its altitude1 etc41 are n ! only important matt]s "o mu/ consid] 9 ! case ( ! a](oil1 we mu/ also consid]-- #i4 ,its ,aspect ,ratio1 i4e4 ! ratio ( ! span 7l5g?7 ( ! a](oil to ! *ord--usually express$ by span_/*ord4 ,9 ! ,f>man ma*9e ?is ratio is #ed2 ,blriot1 #dc2 ,%ort1 #f to #ge2 ,roe triplane1 #ge2 a ,cl>k fly]1 #if4 ,n[ ! high] ! aspect ratio ! great] %\ld be ! effici5cy4 ,air escap+ by ! sides repres5ts loss1 & ! l5g? ( ! sides %\ld be kept %ort4 ,a broad] a](oil means a /eep] angle ( incl9ation1 less /ability1 unnecess>y wa/e ( p[]1 & is totally unsuit$ = a model--to say no?+ ( a full-siz$ ma*9e4 ,9 models ?is aspect ratio may ) advantage be giv5 a high] value ?an 9 full-siz$ ma*9es1 :]e x is well kn[n a practical safe con/ructional limit is rea*$ long be=e !ory sugge/s ! limit4 ,! difficulty consi/s 9 con/ruct+ models hav+ a v high aspect ratio1 & yet possess+ suffici5t /r5g? & lightness = successful flight4 ,x is 9 su* a case z ?is :]e ! skill & +5uity ( ! design] & build] come 94 ,x is ?is v "q ( aspect ratio :i* has giv5 u ! monoplane1 ! biplane1 & ! triplane4 ,a biplane has a high] aspect ratio ?an a monoplane1 & a triplane 7see above7 a high] ratio /ill4 ,x w be notic$ ! ,cl>k model giv5 has a consid]ably high] aspect ratio1 viz4 #if4 ,& ev5 ?is c be exce$$4 ,an aspect ratio ( #aj3a or ev5 #ab3a %\ld be us$ if possible4#cg #aj4 ,con/ant or ,v>y+ ,camb]4--,"s model mak]s v>y ! camb] ( _! a](oils1 mak+ !m almo/ flat 9 "s p>ts1 ) consid]able camb] 9 o!rs2 ! t5d5cy 9 "s cases be+ to flatt5 ! c5tral portions ( ! a](oil1 & ) increas+ camb] t[>ds ! tips4 ,9 o!rs ! opposite is done4 ,! writ] has made a numb] ( exp]im5ts on ?is subject1 b _c say he has arriv$ at any v decisive results1 save t ! camb] %\ld 9 all cases be 7z /at$ be=e7 v slight1 & s f> z 8 exp]im5ts d %[ any?+1 !y incl9e t[>ds ! fur!r flatt5+ ( ! camb] 9 ! end portions ( ! a](oil4 ,x mu/ n be =gott5 t a flat-surfac$ a](oil1 con/ruct$ z x is ( m or less ela/ic mat]ials1 assumes a natural camb]1 m or less1 :5 driv5 horizontally ?r\gh ! air4 ,ref]5ce has be5 made to a rev]sal ( !-- #aa4 ,c5tre ( ,pressure on ,ar*$ ,surfaces4--,wilbur ,wright 9 8 explanation ( ?is rev]sal says3 ,?is ph5om5on is due to ! fact t at small angles ! w9d /rikes ! =w>d "p ( ! a](oil surface on ! upp] side in/ead ( ! l[]1 & ?us ?is "p altoge!r ceases to lift1 in/ead ( be+ ! mo/ effective "p ( all4 ,! :ole "q hangs on ! value ( ! critical angle at :i* ?is rev]sal takes place2 "s exp]im5ts made by ,mr4 ,m4,b4 ,sell]s 9 #aijf 7publi%$ 9 ,flight1 ,may #ad1 #aiaj7 place ?is angle betwe5 #af & #bj4 ,?is angle is mu* above t us$ 9 model a]oplanes1 z well z 9 actual full-siz$ ma*9es4 ,b ! equilibrium ( ! model might be upset1 n by a *ange ( attitude on its "p1 b on t ( ! w9d1 or bo? comb9$4 ,by giv+ 7z already advis$7 ! a](oil a high aspect ratio we limit ! travel ( ! c5tre ( pressure1 = a high aspect ratio means1 z we h se51 a %ort *ord2 & ?is is an additional reason = mak+ ! aspect ratio z high z practically possible4 ,! "q is1 is ! critical angle really z high z ,mr4 ,sell]'s exp]im5ts w\ld %[4 ,fur!r exp]im5ts are mu* ne$$4 ,,footnotes3 #cg ,nev]!less "s models ) a v l[ aspect ratio make good fly]s1 ow+ to _! extreme lightness4 ,,*apt] ,,vii4 ,,mat]ials ,,= ,,a]oplane ,,con/ruction4 #a4 ,! *oice ( mat]ials = model a]oplane con/ruction is m or less limit$1 if ! be/ results are to be obta9$4 ,! lightness absolutely ess5tial to success necessitates--9 addition to skilful build+ & be/ disposition ( ! mat]ials--mat]ials ( no undue weight relative to _! /r5g?1 ( great ela/icity1 & especially ( great resili5ce 7capacity to absorb %ock )\t injury74 #b4 ,bamboo4--,bamboo has p] p\nd weight a great] resili5ce ?an any o!r suitable sub/ance 7silk & rubb] are obvi\sly useless z p>ts ( ! framework ( an a]oplane74 ,on full-siz$ ma*9es ! difficulty ( mak+ suffici5tly /rong connections & a liability to split1 9 ! l>g] sizes1 are suffici5t reasons = its n be+ made m use (2 b x makes an almo/ ideal mat]ial = model con/ruction4 ,! be/ "p to use 7split out f ! c5trepiece7 is ! /rip ( t\gh wood imm$iately bel[ ! h>d glaz$ surface4 ,= /ruts1 sp>s1 & ribs x c be us$ 9 ?is mann]1 & = ! long /rut support+ ! rubb] motor an entire tube piece %\ld be us$ ( ! requisite /r5g? requir$2 = an ord9>y rubb] motor 7"o y>d long71 #cj to #ej /r&s1 ?is %\ld be a piece #c_/h 94 9 diamet]1 & weight ab\t #e_/h oz4 p] ft4 ,bamboo may be b5t by ei!r ! dry heat f a _s lamp or /ove1 or x may be /eam$1 ! latt] = pref]5ce1 z !re is no dang] ( scor*+ ! fibres on ! inside ( ! b5d4 ,:5 b5t 7z 9 ! case ( o!r woods7 x %\ld be b\nd on to a =m] hav+ a some:at great] curvature ?an ! curve requir$1 because :5 cool & dry x w be sure to g back slightly4 ,x mu/ be left on ! =m] till q dry4 ,:5 b5d+ ! tube entire1 & n split portions !re(1 x %\ld be imm]s$ 9 v hot1 or ev5 boil+1 wat] = "s "t be=e /eam+4 ,! really successful b5d+ ( ! tube en bloc requires consid]able pati5ce & c>e4 ,bamboo is incl9$ to split at ! ends1 & "s c>e is requir$ 9 mak+ jo9ts4 ,! ribs c be atta*$ to ! sp>s by la%+ !m to ?9 ,t /rips ( light metal1 su* z alum9ium4 ,?9 ?read1 or silk1 is pref]able to v ?9 wire = la%+ purpose1 z ! latt] gives too mu*1 & cuts into ! fibres ( ! wood z well4 #c4 ,a%1 ,spruce1 ,:itewood are woods t are also mu* us$ by model mak]s4 ,_m pref] ! la/ nam$ ow+ to its uni=m fre$om f knots & ease ) :i* x c be work$4 ,x is /at$ #ae p] c5t4 additional /r5g? c be imp>t$ by us+ hot size & all[+ x to soak into ! wood at an increase only ( #cg p] c5t4 ( weight4 ,x is less ?an half ! weight ( bamboo1 b has a transv]se rupture ( only #g1ijj lb4 p] sq4 94 comp>$ to #bb1ejj 9 ! case ( bamboo tub+ 7?ickness "o-eigh? diamet]7 & a resili5ce p] lb4 weight ( slightly m ?an "o half4 ,"s model mak]s advocate ! use ( popl> ow+ to its extreme lightness 7ab\t ! same z :itewood71 b its /r5g? is less 9 ! ratio ( ab\t #d3c2 its resili5ce is v slightly m4 ,x mu/ be rememb]$ t wood ( ! same k9d c diff] mu* z to its /r5g?1 etc41 ow+ to :at "p ( ! tree x may h be5 cut f1 ! mann] 9 :i* x may h be5 season$1 etc4 ,= model a]oplanes all wood us$ %\ld h be5 at lea/ a ye> 9 season+1 & %\ld be s treat$ :5 9 ! /ructure t x _c absorb moi/ure4 ,if we take ! resili5ce ( a% z #a1 !n 7accord+ to ,haswell7 relative resili5ce ( bee* is #jhf1 & spruce #jfd4 ,! /ronge/ ( woods has a weight :5 well season$ ( ab\t #dj lb4 p] cub4 ft4 & a t5acity ( ab\t #aj1jjj lb4 p] sq4 94 ,illu/ration3 ,,fig4 #dg;,a4--,,a]oplane ,,alma4 ,a v effective ,fr5* ,toy ,monoplane4 #d4 ,/eel4--,a% has a transv]se rupture ( #ad1cjj lb4 p] sq4 941 /eel tub+ 7?ickness #a_/cj its diamet]7 #ajj1jjj lb4 p] sq4 94 ,a% weighs p] cub4 ft4 #dg lb41 /eel #dij4 ,/eel be+ m ?an t5 times z heavy z a%--b a transv]se rupture /ress sev5 times z high4 ,bamboo 9 tube =m1 ?ickness "o-?ird ( diamet]1 has a transv]se rupture ( #bb1ejj lb4 p] sq4 941 & a weight ( #ee lb4 p] cub4 ft4 ,/eel !n is n9e times z heavy z bamboo--& has a transv]se rupture /ress #dd times z great4 ,9 comp>+ ^! ?ree sub/ances x mu/ be c>efully borne 9 m9d t lightness & /r5g? are n ! only ?+s t h to be provid$ = 9 model a]oplane build+2 !re is ! "q ( resi/ance--we mu/ (f] z small a cross-section to mov+ ?r\gh ! air z possible4 ,n[ :ile a% or bamboo & c]ta9 o!r timb]s may c>ry a high] load p] unit ( weight ?an /eel1 !y w pres5t ab\t ?ree to ?ree & a half times ! cross-section1 & ?is produces a s]i\s ob/acle1 :ile o!rwise meet+ c]ta9 requirem5ts t are mo/ desirable4 ,/eel tub+ ( suffici5tly small bore is n1 s f> z ! writ] kn[s1 yet on ! m>ket 9 ,engl&4 ,9 ,france v ?9 /eel tubes are made ( r\nd1 oval1 hexagon1 etc41 %ape1 & ( accurate ?ickness ?r\gh\t1 ! price be+ ab\t #ahs4 a lb4 ,al?\gh suitable /eel tub+ is n yet procurable "u ord9>y circum/ances1 umbrella /eel is4 #e4 ,umbrella ,section ,/eel is a section #e_/cb 94 by #a_/h 94 deep1 #f ft4 long weigh+ #ba oz41 & a section #c_/cb 94 across ! base by #a_/h 94 deep1 #f ft4 long weigh+ #aie oz4 ,x is (t5 /at$ t umbrella ribs are too heavy--b ?is entirely dep5ds on ! l5g? y make use (1 9 l5g?s ( #be 94 = small a](oils made f su* l5g?s x is s2 b 9 l5g?s ( #dh 94 7two su* l5g?s jo9$ toge!r7 ! writ] has us$ x ) great success2 (t5 mak+ use ( x n[ 9 8 l>g] models2 ! p>ticul> size us$ by him weighs #ac grammes1 to a l5g? ( #be 94 ,he has nev] _h "o ( ^! a](oils break or become k9k$--?9 piano wire is us$ to /ay !m & also = sp>s :5 employ$--! front & ends ( ! a](oil are ( umbrella /eel1 ! trail+ edge ( /eel wire1 comp>atively ?91 kept taut by /eel wire /ays4 #f4 ,/eel ,wire4--,t5sile /r5g? ab\t #cjj1jjj lb4 p] sq4 94 ,= ! a](oil framework ( small models & = all purposes ( /ay+1 or :]e a v /rong & light t5sion is requir$1 ?is sub/ance is invaluable4 ,also = framework ( light fabric cov]$ propell]s z well z = skids & %ock absorb]--also = hooks to hold ! rubb] motor /r&s1 etc4 ,no model is complete )\t x 9 "s =m or ano!r4 #g4 ,silk4--,?is aga9 is a s9e qua non4 ,silk is ! /ronge/ ( all organic sub/ances = c]ta9 p>ts ( a]oplane con/ruction4 ,x has1 9 its be/ =m1 a specific gravity ( #ac1 & is ?ree times z /rong z l951 & twice z /rong 9 ! ?read z hemp4 ,its f9e/ fibres h a section ( f #jjjaj to #jjjae 9 diamet]4 ,x w su/a9 ab\t #ce1jjj lb4 p] sq4 94 ( its cross section2 & its susp5d$ fibre %\ld c>ry ab\t #aej1jjj ft4 ( its own mat]ial4 ,?is is six times ! same figure = alum9ium1 & equals ab\t #ge1jjj lb4 /eel t5acity1 & #ej m ?an is obta9$ ) /eel 9 ! =m ( wat* spr+s or wire4 ,= a](oil surface no sub/ance c comp>e ) x4 ,b x mu/ be us$ 9 ! =m ( an oil$ or specially treat$ silk4 ,sev]al su* are on ! m>ket4 ,h>t's fabric & radium silk are p]haps ! be/ kn[n4 ,silk weighs #fb lb4 p] cub4 ft41 /eel has1 we h se51 #dij lb41 ?us pay+ due reg>d to ?is & to its v high t5sile /r5g? x is sup]ior to ev5 /eel wire /ays4 #h4 ,alum9ium & ,magnalium4--,two sub/ances ab\t :i* a great deal has be5 he>d 9 connection ) model a]oplan+2 b ! writ] does n recomm5d _! use save 9 ! case ( fitt+s = scale models1 n actual fly]s1 unless especially light ones meant to fly ) ! w9d4 ,nei!r c comp>e ) /eel4 ,/eel1 x is true1 is ?ree times z heavy z alum9ium1 b x has f\r or five times its /r5g?2 & :]eas alum9ium & magnalium may ) safety be giv5 a p]missible break+ /r5g? ( #fj p] c5t4 & #hj p] c5t4 respectively1 /eel c easily be giv5 #hj p] c5t4 ,be+ also less 9 section1 resi/ance to air travel is aga9 less z 9 ! case ( wood4 ,9 fact1 /eel scores all r\nd4 ,weight ( magnalium 3 weight ( alum9ium 33 #h3i4 #i4 ,alloys4--,dur+ rec5t ye>s scores1 hundr$s1 possibly ?\s&s ( diff]5t alloys h be5 tri$ & exp]im5t$ on1 b /eel /ill easily holds its own4 ,x is no use a sub/ance be+ light] ?an ano!r volume = volume1 x mu/ be light] & /rong] weight = weight1 to be sup]ior = a]onautical purpose1 & if ! diff]5ce be b slight1 "q ( bulk may decide x z (f]+ less resi/ance4 #aj4 ,%eet ,ebonite4--,?is sub/ance is sometimes useful = exp]im5ts ) small propell]s1 = x c be b5t & m\ld$ 9 hot wat]1 & :5 cold sets & keeps its %ape4 ,vulcaniz$ fibre c be us$ = same purpose4 ,%eet celluloid c be us$ 9 ! same way1 b 9 "t x becomes brittle & %r9ks4 ,mica %\ld be avoid$4 ,jo9tless cane 9 v>i\s sizes is a v useful mat]ial--! ma9 a](oil c be built ( x1 & x is useful = skids1 & might be made m use ( ?an x is4#ch ,?ree ply wood1 f #a_/ej 94 9 ?ickness1 is n[ on ! m>ket4 ,f\r or five ply wood c also be obta9$4 ,to ^? desir+ to build models hav+ wood5 a](oils su* woods (f] ! advantage ( great /r5g? & extreme lightness4 ,ref]r+ to ,table ,v4 7,timb]7 at ! end ( ! book1 app>5tly ! mo/ suitable wood is ,lomb>dy popl>2 b its light weight means increas$ bulk1 i4e4 additional air resi/ance4 ,honduras mahogany is really a bett] all-r\nd wood1 & bee* is n f> beh9d4 ,resili5ce is an important factor4 ,a% heads ! li/2 b mahogany's factor is also good1 & 9 o!r respects sup]ior4 ,lomb>dy popl> ought to be a v good wood = propell]s1 ow+ to its lightness & ! ease ) :i* x c be work$4 ,holl[ re$s1 & ev5 porcup9e quills1 h be5 press$ into ! s]vice ( ! model mak]1 & ow+ to _! great /r5g? & extreme lightness1 m especially ! latt]1 are n )\t _! uses4 ,,footnotes3 #ch ,! *ief advantage ( cane--its want ( /iffness1 or facility 9 b5d+--is = "s p>ts ( ! ma*9e its *ief disadvantage1 :]e /iffness ) resili5ce is mo/ requir$4 ,,*apt] ,,viii4 ,,h9ts ,,on ,,! ,,build+ ,,( ,,model ,,a]oplanes4 #a4 ,! *ief difficulty 9 ! design+ & build+ ( model a]oplanes is to successfully combat ! conflict+ int]e/s conta9$ !re94 ,weight gives /ability1 b requires extra support+ surface or a high] spe$1 i4e4 m p[]1 i4e4 m weight4 ,ineffici5cy 9 "o "p has a t]rible mann] ( repeat+ itself2 = in/ance1 suppose ! a](oil surface ineffici5t--badly design$--?is means m resi/ance2 m resi/ance means m p[]1 i4e4 weight1 i4e4 m surface1 & s on ad inf9itum4 ,x is because ( circum/ances l ! above t x is s difficult to design really good & effici5t fly+ models2 ! actual build+ ( !m is n s difficult1 b few tools are requir$1 none t are exp5sive or difficult to use4 ,9 ! mak+ ( any p>ticul> model !re are special po9ts t require special att5tion2 b !re are c]ta9 g5]al rules & features :i* if n adh]$ to & c>efully c>ri$ out1 or z c>efully avoid$1 w cause endless tr\ble & failure4 #b4 ,9 con/ruct+ a model a]oplane1 or1 inde$1 any piece ( a]ial app>atus1 x is v important n to int]rupt ! cont9uity ( any rib1 tube1 sp>1 etc41 by drill+ holes or mak+ too ?9n$ d[n hold+ places2 if su* be done1 additional /r5g? by b9d+ 7) ?read1 n wire71 or by slipp+ a small piece ( slightly l>g] tube ov] ! o!r1 mu/ be imp>t$ to ! app>atus4 #c4 ,beg9 by mak+ a simple monoplane1 & aft]w>ds z y ga9 skill & exp]i5ce proce$ to con/ruct m elaborate & sci5tific models4 #d4 ,le>n to sold]--if y d n "k h[ to--x is absolutely ess5tial4 #e4 ,d n con/ruct models 7int5d$ = actual flight7 ) a tractor screw-ma9 plane 9 front & tail 7beh9d74 ,avoid !m z y w\ld ! plague4 ,allusion has already be5 made 9 ! ,introduction to ! difficulty ( gett+ ! c5tre ( gravity suffici5tly =w>d 9 ! case ( ,blriot models2 aga9 ) ! ma9 a](oil 9 front1 x is ?is a](oil & n ! balanc+ elevator1 or tail1 t fir/ enc\nt]s ! upsett+ gu/1 & ! effect ( su* a gu/ act+ fir/ on ! l>g] surface is (t5 m ?an ! balanc] c rectify 9 "t to av]t disa/]4 ,! prop] place = ! propell] is beh9d1 9 ! wake ( ! ma*9e4 ,if ! screw be 9 front ! backwa% f x /rikes ! ma*9e & has a decid$ly ret>d+ action4 ,x is (t5 cont5d$ t x drives ! air at an increas$ velocity "u 7& ov]7 ! ma9 a](oil1 & s gives a great] lift+ effect4 ,b = prop] lift+ effect :i* x c turn )\t ef=t into air columns ( prop] /ream l9e =m :at ! a](oil requires is undi/urb$ air--n propell] backwa%4 ,! re> ( ! model is ! prop] place = ! propell]1 9 ! c5tre ( greate/ air di/urbance2 9 su* a position x w recov] a portion ( ! en]gy lo/ 9 imp>t+ a =w>d movem5t to ! air1 caus$ by ! resi/ance1 ! model g5]ally runn+ 9 su* air--! slip ( ! screw is r$uc$ to a correspond+ degree--may ev5 vani% altoge!r1 & :at is kn[n z negative slip occur4 #f4 ,wood5 or metal a](oils are m effici5t ?an fabric cov]$ ones4 ,b !y are only satisfactory 9 ! small] sizes1 ow+1 = "o ?+1 to ! sma% ) :i* !y come to ! gr\nd4 ,?is be+ due to ! high spe$ necess>y to su/a9 _! weight4 ,= l>g]-siz$ models fabric cov]$ a](oils %\ld be us$4 #g4 ,z to ! %ape ( su*1 only ?ree ne$ be consid]$--! 7a7 rectangul>1 7b7 ! elongat$ ellipse1 7c7 ! *amf]$ re> edge4 ,illu/ration3 ,,fig4 #dh4--7;a71 7b71 7c74 #h4 ,! /ret*+ ( ! fabric on ! a](oil framework requires consid]able c>e1 especially :5 us+ silk4 ,x is q possible1 ev5 9 models ( #c ft4 to #d ft4 spread1 to d )\t ribs1 & /ill obta9 a fairly correct a]ocurve1 if ! mat]ial be /ret*$ on 9 a c]ta9 way4 ,x consi/s 9 gett+ a correct longitud9al & transv]se t5sion4 ,we w illu/rate x by a simple case4 ,take a piece ( ?icki% /eel pian(orte wire1 say1 #ah 94 long1 b5d x r\nd into a circle1 all[+ 94 to #a 94 to ov]lap1 t9 & sold]1 b9d ?is ) s(t v ?9 iron wire1 & aga9 sold] 7always use z little sold] z possible74 ,n[ /it* on to ?is a piece ( na9sook or silk1 de=m+ ! circle z y d s until x has ! accompany+ elliptical %ape4 ,! result is "o ( d\ble curvature2 ! transv]se curve 7dih$ral angle7 c be regulat$ by cross ?reads or wires go+ f ,a to ,b & ,c to ,d4 ,illu/ration3 ,,fig4 #di4 ,illu/ration3 ,,fig4 #di;,a4--,,mr4 ,t4,w4,k4 ,,cl>ke',s #a ,,oz4 ,,model4 ,! longitud9al curve on ! camb] c be regulat$ by ! orig9al t5sion giv5 to x1 & by ! mann] ( its fix+ to ! ma9 framework4 ,suitable wire projections or loops %\ld be b\nd to x by wire1 & ^! fa/5$ to ! ma9 framework by b9d+ ) ?9 rubb] cord1 a v useful me?od ( fa/5+1 s9ce x acts z an excell5t %ock absorb]1 & gives :5 requir$1 & yet possesses q suffici5t practical rigidity4 #i4 ,flexible jo9ts are an advantage 9 a biplane2 ^! c be made by fix+ wire hooks & eyes to ! ends ( ! /ruts1 & hold+ !m 9 position by b9d+ ) silk or ?read4 ,rigidity is obta9$ by use ( /eel wire /ays or ?9 silk cord4 ,illu/ration3 ,,fig4 #di;,b4--,,mr4 ,t4,w4,k4 ,,cl>ke',s #a ,,oz4 ,,model4 ,%[+ ! position ( ,c4 ( ,g41 or po9t ( support4 #aj4 ,ow+ to ! extra weight & difficulties ( con/ruction on s small a scale x is n desirable to use d\ble surface a](oils except on l>ge size p[]-driv5 models4 #aa4 ,x is a good plan n to h ! rod or tube c>ry+ ! rubb] motor connect$ ) ! outrigg] c>ry+ ! elevator1 because ! torque ( ! rubb] t5ds to twi/ ! c>ry+ framework1 & int]f]es ) ! prop] & correct action ( ! elevator4 ,if x be s connect$ ! rod mu/ be /ay$ ) piano wire1 bo? longitud9ally 7to ov]come ! pull :i* we "k is v great71 & also lat]ally1 to ov]come ! torque4 ,illu/ration3 ,,fig4 #di;,c4--,a ,,l>ge ,,model ,,a]oplane4 ,%[n )\t rubb] or propell]s4 ,design$ & con/ruct$ by ! writ]4 ,z a te/ x 0 fitt$ ) two #ad 94 propell]s revolv+ 9 ! same direction1 & made "s excell5t flights "u ^! conditions1 roll+ slightly across ! w9d1 b o!rwise keep+ q /eady4 ,total weight1 #a lb42 l5g?1 #f ft42 span ( ma9 a](oil1 #e ft4 ,con/ruct$ ( bamboo1 cane1 & /eel wire4 ,front skids /eel wire4 ,back skids cane4 ,a](oil cov]+ na9sook4 #ab4 ,"s build]s place ! rubb] motor above ! rod1 or b[ frame c>ry+ ! a](oils1 etc41 ! idea be+ t ! pull ( ! rubb] di/orts ! frame 9 su* a mann] z to lift ! elevator1 & s cause ! ma*9e to rise rapidly 9 ! air4 ,?is x does2 b ! model naturally drops badly at ! f9i% & spoils ! effect4 ,x is n a pr9ciple t %\ld be copi$4 ,illu/ration3 ,,fig4 #di;,d4--,a ,,v ,,light ,,weight ,,model4 ,con/ruct$ by ! au?or4 ,provid$ ) tw9 propell]s ( a modifi$ ,flem+-,williams type4 ,?is ma*9e flew well :5 provid$ ) an abnormal am\nt ( rubb]1 ow+ to ! poor dynamic ?ru/ giv5 by ! propell]s4 #ac4 ,9 ! ,cl>ke models ) ! small front plane1 ! c5tre ( pressure is slightly 9 front ( ! ma9 plane4 ,! balanc+ po9t ( mo/ models is g5]ally slightly 9 front1 or j )9 ! front edge ( ! ma9 a](oil4 ,! be/ plan is to adju/ ! rod c>ry+ ! rubb] motor & propell] until ! be/ balance is obta9$1 !n hang up ! ma*9e to asc]ta9 ! c5tre ( gravity1 & y w h 7approximately7 ! c5tre ( pressure4 ,illu/ration3 ,,fig4 #di;,e4--,,useful ,,fitt+s ,,= ,,models4 #a4 ,rubb] tyr$ :eels4 #b4 ,ball-be>+ /eel axle %afts4 #c4 ,brass wire /ra9]s ) /eel screws2 break+ /ra9 #bjj lb4 #d4 ,magnalium tub+4 #e4 ,/eel eyebolt4 #f4 ,alum9ium ,t jo9t4 #g4 ,alum9ium ,l piece4 #h4 ,brass braz$ fitt+s4 #i4 ,ball-be>+ ?ru/4 #aj4 ,flat alum9ium ,l piece4 7,! above illu/rations tak5 7by p]mission7 f ,messrs4 ,gamage's catalogue on ,model ,aviation47 #ad4 ,! elevator 7or tail7 %\ld be ( ! non-lift+ type--9 o!r words1 ! entire weight %\ld be c>ri$ by ! ma9 a](oil or a](oils2 ! elevator be+ us$ simply z a balanc]4#ci ,if ! ma*9e be s con/ruct$ t "p ( ! weight be c>ri$ by ! elevator1 !n ei!r x mu/ be l>ge 79 proportion7 or set up at a l>ge angle to c>ry x4 ,bo? mean consid]ably m resi/ance--:i* is to be avoid$4 ,9 practice ?is means ! propell] be+ "s little di/ance 9 re> ( ! ma9 support+ surface4 ,illu/ration3 ,,fig4 #di;,f4--,,useful ,,fitt+s ,,= ,,models4 #aa4 ,alum9ium ball ?ru/ & racket4 #ab4 ,ball-be>+ propell]1 ?ru/1 & /ay4 7,! above illu/rations tak5 7by p]mission7 f ,messrs4 ,gamage's catalogue on ,model ,aviation47 #ae4 ,9 actual fly+ models skids %\ld be us$ & n :eels2 ! latt] to be ( any real use mu/ be ( l>ge diamet]1 & ! weight is prohibitive4 ,skids c be con/ruct$ ( cane1 imitation :alebone1 /eel wat* or clock-spr+1 /eel pian(orte wire4 ,/eel ma9spr+s are bett] ?an imitation :alebone1 b /eel pian(orte wire be/ ( all4 ,= l>g] siz$ models bamboo is also suitable1 z also a% or /rong cane4 #af4 ,ap>t f or 9 conjunction ) skids we h :at are t]m$ %ock absorb]s to less5 ! %ock on l&+--! same sub/ances c be us$--/eel wire 9 ! =m ( a loop is v effectual2 :alebone & /eel spr+s h a knack ( snapp+4 ,^! %ock absorb]s %\ld be s atta*$ z to give all ways = a "p side & "p front l&+ z well z a direct front l&+4 ,= ?is purpose !y %\ld be la%$ to ! ma9 frame by ?9 indi>ubb] cord4 #ag4 ,9 ! case ( a biplane model ! gap mu/ n be less ?an ! *ord--pref]ably great]4 ,9 a d\ble monoplane 7( ! ,langley type7 !re is consid]able int]f]5ce1 i4e4 ! re> plane is mov+ 9 air already act$ on by ! front "o1 & !re=e mov+ 9 a d[nw>d direction4 ,?is means decreas$ effici5cy4 ,x c be ov]come1 m or less1 by v>y+ ! dih$ral angle at :i* ! two planes are set2 b _c be got rid ( altoge!r1 or by plac+ !m f> ap>t4 ,9 biplanes n possess+ a dih$ral angle--! propell] c be plac$ slightly to "o side--9 ord] to neutralise ! torque ( ! propell]--! be/ portion %\ld be f\nd by exp]im5t--unless ! pit* be v l>ge2 ) a well design$ propell] ?is is n by any means ess5tial4 ,if ! propell] revolve clockwise1 place x t[>ds ! "r h& ( ! ma*9e1 & vice v]sa4 #ah4 ,9 design+ a model to fly ! longe/ possible di/ance ! monoplane type %\ld be *os51 & :5 desir+ to build "o t %all rema9 ! longe/ "t 9 ! air ! biplane or triplane type %\ld be adopt$4#dj ,= ! longe/ possible flight tw9 propell]s revolv+ 9 opposite directions#da are ess5tial4 ,to take a concrete case--"o ( ! writ]'s models weigh$ complete ) a s+le propell] #h oz4 ,x 0 !n alt]$ & fitt$ ) two propell]s 7same diamet] & weight72 ?is complete ) d\ble rubb] weigh$ #aj oz4 ,! advantage d\ble ! p[]4 ,weight increas$ only #bj p] c5t41 resi/ance ab\t #aj p] c5t41 total #cj p] c5t4 ,ga9 #gj p] c5t4 ,or if ! me?od ( ge>+ advocat$ 7see ,ge>$ ,motors7 be adopt$ !n we %all h f\r bun*es ( rubb] in/ead ( two1 & c !reby obta9 s _m m turns4#db ,! l5g? ( ! /r&s %\ld be su* z to r5d] possible at lea/ a ?\s& turns4 ,! propell]s %\ld be ( l>ge diamet] & pit* 7n less ?an #ce at ! tips71 ( curv$ %ape1 z advocat$ 9 #bb *4 v42 ! a](oil surface ( z high an aspect ratio z possible1 & b slight camb] if any2 ?is is a v difficult "q1 ! "q ( camb]1 & ! writ] feels b\nd to admit he has obta9$ z long flights ) surfaces practically flat1 b :i* d1 ( c\rse1 camb] slightly 9 a suitable w9d1 z ) /iff] camb]$ surfaces4 ,w9d camb]$ surfaces are1 h[ev]1 totally unsuitable 9 gu/y wea!r1 :5 ! w9d has frequ5tly a d[nw>d tr5d1 :i* has ! effect ( camb]+ ! surface ! wrong way ab\t1 & plac+ ! ma*9e flat on ! gr\nd4 ,oil$ or specially prep>$ silk ( ! lighte/ k9d %\ld be us$ = surfac+ ! a](oils4 ,"s =m ( keel1 or f91 is ess5tial to assi/ 9 keep+ ! ma*9e 9 a /raight c\rse1 comb9$ ) a rudd] & univ]sally jo9t$ elevator4 ,! mann] ( w9d+ up ! propell]s has already be5 ref]r$ to 7see *ap4 iii41 #i74 ,a w9d] is ess5tial4 ,ano!r =m ( a](oil is "o ( wood 7z 9 ,cl>ke's fly]s7 or metal1 su* a ma*9e rely+ m on ! swiftness ( its flight ?an on its duration4 ,9 ?is ! ge>+ w\ld possibly n be s advantage\s--b exp]im5t alone c\ld decide4 ,! weight ( ! ma*9e w\ld require to be an absolute m9imum1 & ev]y?+ n absolutely ess5tial omitt$4 ,x is q possible to build a tw9-screw model on "o c5tral /ick alone2 b ! isosceles triangul> =m ( framework1 ) two propell]s at ! base corn]s1 & ! rubb] motors runn+ along ! two sides & t]m9at+ at ! v]tex1 is pref]r$ by mo/ model mak]s4 ,x entails1 ( c\rse1 extra weight4 ,a light =m ( skid1 made ( /eel pian(orte wire1 %\ld be us$4 ,z to ! weight & size ( ! model1 ! n[ fam\s "o-ounc]s h made "s long flights ( ov] #cjj y>ds#dc2 b ! ma*9e claim+ ! record1 half a mile1#dd weighs ab\t #aj oz4 ,& ap>t f ?is latt] consid]ation altoge!r ! writ] is incl9$ to ?9k t f #e oz4 to #aj oz4 is likely to prove ! mo/ suitable4 ,x is n too l>ge to exp]im5t ) )\t difficulty1 nor is x s small z to require ! skill ( a jewell] almo/ to build ! necess>y me*anism4 ,! propell] spe$ has already be5 discuss$ 7see *4 v41 #ae74 ,! model w1 ( c\rse1 be fl[n ) ! w9d4 ,! total l5g? ( ! model %\ld be at lea/ twice ! span ( ! ma9 a](oil4 ,,footnotes3 #ci ,?is is a good plan--n a rule4 ,good fly+ models c1 ( c\rse1 be made 9 :i* ?is does n hold4 #dj ,?is is 9 !ory only3 9 practice ! monoplane holds bo? records4 #da ,! be/ position = ! propell]s appe>s to be "o 9 front & "o beh9d1 :5 extreme lightness is ! *ief ?+ desir$4 #db ,because ! numb] ( /r&s ( rubb] 9 ea* bun* w be mu* less4 #dc ,mr4 ,burge ,webb claims a record ( #ejj y>ds = "o ( 84 #dd ,fly+1 ( c\rse1 ) ! w9d4 ,note4--,9 ! ,model ,eng9e] ( ,july #g1 #aiaj1 w be f\nd an int]e/+ acc\nt 7) illu/rations7 ( ,mr4 ,w4,g4 ,a/on's #a oz4 model1 :i* has rema9$ 9 ! air = ov] a m9ute4 ,,*apt] ,,ix4 ,,! ,,/e]+ ,,( ,,! ,,model4 #a4 ,( all ! v>i\s sections ( model a]oplan+ t :i* is ! lea/ satisfactory is ! above4 ,! torque ( ! propell] naturally ex]ts a twi/+ or tilt+ effect ^u ! model z a :ole1 ! effect ( :i* is to cause x to fly 9 7r\ghly speak+7 a circul> c\rse1 ! direction dep5d+ on :e!r ! pit* ( ! screw be a "r or left h&$ "o4 ,!re are v>i\s devices by :i* ! torque may be 7approximately7 got rid (4 #b4 ,9 ! case ( a monoplane1 by n plac+ ! rod c>ry+ ! rubb] motor 9 ! exact c5tre ( ! ma9 a](oil1 b slightly to "o side1 ! exact position to be det]m9$ by exp]im5t4 ,9 a biplane ! same result is obta9$ by keep+ ! rod 9 ! c5tre1 b plac+ ! bracket c>ry+ ! be>+ 9 :i* ! propell] %aft runs at "r angles horizontally to ! rod to obta9 ! same effect4 #c4 ,! mo/ obvi\s solution ( ! problem is to use two equal propell]s 7z 9 ! ,wright biplane7 ( equal & opposite pit*1 driv5 by two rubb] motors ( equal /r5g?4 ,!oretically ?is idea is p]fect4 ,9 practice x is n s4 ,x is q possible1 ( c\rse1 to use two rubb] motors ( an equal numb] ( /r&s 7equality %\ld be fir/ te/$ by weigh+74 ,x %\ld be possible to obta9 two propell]s ( equal & opposite pit*1 etc41 & x is also possible to give ! rubb] motors ! same numb] ( turns4 ,9 practice "o is always w\nd up be=e ! o!r4 ,?is is ! fir/ mi/ake4 ,!y %\ld be w\nd up at ! same "t1 us+ a d\ble w9d] made = ! purpose4 ,! fact t ?is is n done is q suffici5t to give an unequal torsion4 ,! friction 9 bo? cases mu/ also be exactly equal4 ,bo? propell]s mu/ be releas$ at exactly ! same in/ant4 ,suppos+ all ^! conditions fulfill$ 79 practice !y nev] are71 suppos+ also ! propell]s connect$ by ge>+ 7prohibitive on acc\nt ( ! weight71 & ! air q calm 7:i* x nev] is71 !n ! ma*9e %\ld & und\bt$ly w\ld fly /raight4 ,= /e]+ purposes by w9d+ up "o propell] _m m times ?an ! o!r1 ! a]oplane c g5]ally speak+ be /e]$ to ! "r or left2 b f :at ,i h bo? se5 & tri$ tw9-screw model a]oplanes are n ! success !y are (t5 made out to be1 & !y are mu* m tr\blesome to deal )1 9 spite ( :at "s say to ! contr>y4 ,! solution ( ! problem ( /e]+ by ! use ( two propell]s is only p>tially satisfactory & reliable1 9 fact1 x is no solution at all4#de ,! torque ( ! propell] & consequ5t tilt+ ( ! a]oplane is n ! only cause at "w div]t+ ! ma*9e f its c\rse4 #d4 ,z x progresses ?r\gh ! air x is con/antly meet+ air curr5ts ( v>y+ velocity & direction1 all t5d+ to make ! model deviate m or less f its c\rse2 ! be/ way1 9 fact1 ! only way1 to successfully ov]come su* is by means ( spe$1 by giv+ ! a]oplane a high velocity1 n ( t5 or twelve to fifte5 miles an h\r1 z is usual 9 built up fabric-cov]$ a](oils1 b a velocity ( tw5ty to ?irty miles an h\r1 atta9able only 9 models 7petrol or /eam driv57 or by means ( wood5 or metal a](oils4 #e4 ,among/ devices us$ = horizontal /e]+ are v]tical ,,f9s4 ,^! %\ld be plac$ 9 ! re> above ! c5tre ( gravity4 ,!y %\ld n be l>ge1 & c be made ( fabric tightly /ret*$ ov] a wire frame1 or ( a piece ( %eet magnalium or alum9ium1 turn+ on a pivot at ! front edge1 adju/m5t be+ made by simply twi/+ ! f9 r\nd to ! desir$ angle4 ,z to ! size1 ?9k ( rudd] & ! size ( a boat1 b all[ = ! diff]5ce ( m$ium4 ,! frame c>ry+ ! pivot & f9 %\ld be made to slide along ! rod or backbone ( ! model 9 ord] to f9d ! mo/ effici5t position4 #f4 ,/e]+ may also be attempt$ by means ( little balanc+ tips1 or ail]ons1 fix$ to or ne> ! ma9 a](oil1 & pivot$ 7ei!r c5trally or o!rwise7 9 su* a mann] t !y c be rotat$ "o 9 "o direction 7tilt$7 & ! o!r 9 ! o!r 7dipp$71 s z to raise "o side & depress ! o!r4 #g4 ,! model c also be /e]$ by giv+ x a cant to "o side by weight+ ! tip ( ! a](oil on t side on :i* x is desir$ x %\ld turn1 b ?is me?od is bo? clumsy & weighty4 #h4 ,ano!r way is by means ( ! elevator2 & ?is me?od1 s9ce x entails no additional surfaces entail+ extra resi/ance & weight1 is p]haps ! mo/ satisfactory ( all4 ,x is necess>y t ! elevator be m\nt$ on "s k9d ( univ]sal jo9t1 9 ord] t x may n only be tipp$ or dipp$1 b also cant$ sideways = horizontal /e]+4 #i4 ,a v]tical f9 9 ! re>1 or some?+ 9 ! nature ( a keel1 i4e4 a v]tical f9 runn+ d[n ! backbone ( ! ma*9e1 greatly assi/s ?is movem5t4 ,if ! model be ( ! tractor screw & tail 7,blriot7 type1 !n ! above rem>ks re elevator apply mutatis mut&is to ! tail4 #aj4 ,x is ( ! mo/ vital importance t ! propell] torque %\ld be1 z f> z possible1 correctly balanc$4 ,?is c be te/$ by balanc+ ! model transv]sely on a knife edge1 w9d+ up ! propell]1 & all[+ x to run d[n1 & adju/+ matt]s until ! torque & comp5satory app>atus balance4 ,z ! torque v>ies ! mean %\ld be us$4 ,9 ! case ( tw9 propell]s1 susp5d ! model by its c5tre ( gravity1 w9d up ! propell]s1 & :5 runn+ d[n if ! model is drawn =w>d )\t rotation ! ?ru/ is equal2 if n adju/m5t mu/ be made till x does4 ,! easie/ way to d ?is may be by plac+ "o propell]1 ! "o giv+ ! great] ?ru/1 slightly ne>] ! c5tre4 ,9 ! case ( two propell]s rotat+ 9 opposite directions 7by suitable ge>+7 on ! common c5tre ( two axes1 "o ( ! axes be+1 ( c\rse1 holl[1 & turn+ on ! o!r--! re> propell] work+ 9 air already driv5 back by ! o!r w require a co>s] pit* or l>g] diamet] to be equally effici5t4 ,,footnote3 #de ,^! rem>ks apply to rubb] driv5 motors4 ,9 ! case ( two-p[] driv5 propell]s 9 :i* ! p[] 0 automatically adju/$1 say1 by a gyroscope z 9 ! case ( a torp$o--& ! spe$ ( ea* propell] v>i$ accord+ly--! ma*9e c\ld1 ( c\rse1 be easily /e]$ by su* means2 b ! model to c>ry su* p[] & appliances w\ld c]ta9ly weigh f #dj lb4 to #fj lb4 ,,*apt] ,x4 ,,! ,,laun*+ ,,( ,,! ,,model4 #a4 ,g5]ally speak+1 ! model %\ld be laun*$ into ! air aga9/ ! w9d4 #b4 ,x %\ld 7!oretically7 be laun*$ into ! air ) a velocity equal to t ) :i* x flies4 ,if x laun* ) a velocity 9 excess ( t x becomes at once un/able & has to settle d[n be=e assum+ its normal l9e ( flight4 ,if ! velocity be insuffici5t1 x may be unable to pick up its requisite velocity 9 "t to prev5t its fall+ to ! gr\nd4 ,models ) wood5 a](oils & a high aspect ratio design$ = swift fly+1 su* z ! well-kn[n ,cl>ke fly]s1 require to be practically hurl$ into ! air4 ,o!r fabric-cov]$ models capable ( su/5tation at a velocity ( #h to #aj miles an h\r1 may j be releas$4 #c4 ,light fea!rweight models design$ = long flights :5 travell+ ) ! w9d %\ld be laun*$ ) x4 ,!y w n advance into x--if !re be any?+ ( a breeze--b1 if well design$1 j hov]1 f9ally s9k+ to e>? on an ev5 keel4 ,_m +5i\s pieces ( app>atus h be5 design$ to me*anically laun* ! model into ! air4 ,fig4 #ej is an illu/ration ( a v simple b effective "o4 #d4 ,= l>ge size p[]-driv5 models1 unless provid$ ) a *assis & :eels to enable !m to run along & rise f ! gr\nd "u _! own p[]1 ! laun*+ is a problem ( consid]able difficulty4 #e4 ,9 ! case ( rubb]-driv5 models desir$ to run along & rise f ! gr\nd "u _! own p[]1 ?is ris+ mu/ be accompli%$ quickly & 9 a %ort space4 ,a model requir+ a #ej ft4 run is useless1 z ! motor w\ld be practically run out by t "t4 ,t5 or twelve feet is ! limit2 n[1 9 ord] to rise quickly ! ma*9e mu/ be light & c>ry consid]able surface1 or1 9 o!r words1 its velocity ( su/5tation mu/ be a l[ "o4 ,illu/ration3 ,,fig4 #ej4--,,mr4 ,,poynt]',s ,,laun*+ ,,app>atus4 7,reproduc$ by p]mission f ! ,model ,eng9e]47 #f4 ,x w n d to tip up ! elevator to a l>ge angle to make x rise quickly1 because :5 once (f ! gr\nd ! angle ( ! elevator is wrong = actual flight & ! model w probably turn a som]sault & l& on its back4 ,i h (t5 se5 ?is happ54 ,if ! elevator be set at an increas$ angle to get x to rise quickly1 !n :at is requir$ is a little me*anical device :i* sets ! elevator at its prop] flight angle :5 x leaves ! gr\nd4 ,su* a device does n pres5t any great me*anical difficulties2 & ,i leave x to ! me*anical +5uity ( my read]s to devise a simple little device :i* %all ma9ta9 ! elevator at a comp>atively l>ge angle :ile ! model is on ! gr\nd1 b all[+ ( ?is angle be+ r$uc$ :5 free flight is comm5c$4 #g4 ,! propell] mo/ suitable to get ! ma*9e (f ! gr\nd is "o giv+ consid]able /atical ?ru/4 ,a small propell] ( f9e pit* quickly />ts a ma*9e1 b is n1 ( c\rse1 s effici5t :5 ! model is 9 actual flight4 ,a rubb] motor is n at all well adapt$ = ! purpose j discuss$4 #h4 ,pr(essor ,kress uses a poli%$ plank 7d[n :i* ! models slip on cane skids7 to laun* 8 models4 #i4 ,:5 laun*+ a tw9-screw model ! model %\ld be held by ea* propell]1 or to speak m correctly1 ! two brackets hold+ ! be>+s 9 :i* ! propell] %afts run %\ld be held "o 9 ea* h& 9 su* a way1 ( c\rse1 z to prev5t ! propell]s f revolv+4 ,hold ! ma*9e v]tically d[nw>ds1 or1 if too l>ge = ?is1 all[ ! nose to re/ slightly on ! gr\nd2 raise 7or sw+7 ! ma*9e up into ! air until a little m ?an horizontal position is atta9$1 & boldly pu% ! ma*9e into ! air 7mov+ =w>d if necess>y7 & release bo? brackets & screws simultane\sly4#df #aj4 ,9 laun*+ a model "s pref] to all[ ! propell]s to revolve = a few mom5ts 7a second1 say7 be=e actually laun*+1 cont5d+ t ?is gives a /eadi] initial flight4 ,?is is und\bt$ly ! case1 see note on page #aaa4 #aa4 ,9 any case1 unless try+ = a height prize1 d n po9t ! nose ( ! ma*9e "r up into ! air ) ! idea t y w !reby obta9 a bett] flight4 ,laun* x horizontally1 or at a v small angle ( incl9ation4 ,:5 requir+ a model to run along a field or a lawn & rise !refrom ?is is mu* facilitat$ by us+ a little /rip ( smoo? oilclo? on :i* x c run4 ,rememb] t swift fly+ wood5 & metal models require a high initial velocity1 p>ticul>ly if ( l>ge size & weight4 ,if ?r[n /eadily & at ! prop] angle !y c sc>cely be ov]?r[n4 ,,footnote3 #df ,ano!r & bett] way--suppos+ ! model con/ruct$ ) a c5tral rod1 or "s suitable holdfa/ 7?is %\ld be situat$ at ! c5tre ( gravity ( ! ma*9e7 by :i* x c be held 9 "o h&--is to hold ! ma*9e ) bo? h&s above ! head1 ! "r h& grasp+ x ready to laun* x1 & ! left hold+ ! two propell]s4 ,release ! propell]s & all[ !m a brief int]val 7ab\t half a second7 to />t4 ,!n laun* boldly into ! air4 ,! writ] has easily laun*$ #a lb4 models by ?is means1 ev5 9 a high w9d4 ,nev] laun* a model by "o h& only4 ,,*apt] ,,xi4 ,,helicopt] ,,models4 #a4 ,!re is no difficulty :atev] ab\t mak+ successful model helicopt]s1 :atev] !re may be ab\t full-siz$ ma*9es4 #b4 ,! e>lie/ fly+ models 7 helicopt]s4 ,z e>ly z #agif ,sir ,george ,cayley con/ruct$ a p]fectly successful helicopt] model 7see *4 iii472 x %\ld be notic$ ! screws 7 sup]impos$ & rotat$ 9 opposite directions4 #c4 ,9 #ahdb a ,mr4 ,phillips con/ruct$ a successful p[]-driv5 model helicopt]4 ,! model 0 made entirely ( metal1 & :5 complete & *>g$ weigh$ #b lb4 ,x consi/$ ( a boil] or /eam g5]ator & f\r fans support$ betwe5 eight arms4 ,! fans _h an incl9ation to ! horizon ( #bj1 & ?r\gh ! arms ! /eam ru%$ on ! pr9ciple ( ,h]o's eng9es 7,b>k]'s ,mill ,pr9ciple probably74 ,by ! escape ( /eam f ! arms ! fans 7 caus$ to revolve ) imm5se en]gy1 s mu* s t ! model rose to an imm5se altitude & flew across two fields be=e x alight$4 ,! motive p[] employ$ 0 obta9$ f ! combu/ion ( *>coal1 nitre & gypsum1 z us$ 9 ! orig9al fire annihilator2 ! products ( combu/ion mix+ ) wat] 9 ! boil] & =m+ gas-*>g$ /eam1 :i* 0 deliv]$ at high pressure f ! extremities ( ! eight arms4#dg ,?is model & its flight 7fully au!nticat$7 is full ( int]e/ & %\ld n be lo/ sight (1 z 9 all probability be+ ! fir/ model actuat$ by /eam :i* actually flew4 ,! helicopt] is b a p>ticul> phase ( ! a]oplane4 #d4 ,! simple/ =m ( helicopt] is t 9 :i* ! torque ( ! propell] is resi/$ by a v]tical loose fabric plane1 s design$ z itself to =m a propell]1 rotat+ 9 ! opposite direction4 ,^! little toys c be b\ght at any good toy %op f ab\t #f;d4 to #as4 ,suppos+ we desire to con/ruct a helicopt] ( a m ambiti\s & sci5tific "*1 possess+ a v]tically rotat+ propell] or propell]s = horizontal propulsion1 z well z horizontally rotat+ propell]s = lift+ purposes4 ,illu/ration3 ,,fig4 #ea4--;,,incorrect ,,way ,,( ,,arrang+ ,,screws4 #e4 ,!re is "o ess5tial po9t t mu/ be c>efully att5d$ to1 & t is1 t ! horizontal propulsive ?ru/ mu/ be 9 ! same plane z ! v]tical lift1 or ! only effect w be to cause our model to turn som]saults4 ,i speak f exp]i5ce4 ,:5 ! horizontally revolv+ propell]s are driv5 9 a horizontal direction _! lift+ p[]s w be mat]ially increas$1 z !y w 7l an ord9>y a]oplane7 be advanc+ on to fre% undi/urb$ air4 #f4 ,i h n = ord9>y purposes advocat$ v light weight wire framework fabric-cov]$ screws1 b 9 a case l ?is :]e ! ?ru/ f ! propell] has to be m ?an ! total weight ( ! ma*9e1 ^! might possibly be us$ ) advantage4 #g4 ,in/ead ( us+ two long v]tical rods z well z "o long horizontal "o = ! rubb] /r&s1 we might disp5se ) ! two v]tical ones altoge!r & use light ge>+ to turn ! torque action ?r\gh a "r angle = ! lift+ screws1 & use ?ree sep>ate horizontal rubb] /r&s = ! ?ree propell]s on a suitable light horizontal framework4 ,su* %\ld result 9 a consid]able sav+ ( weight4 ,illu/ration3 ,,fig4 #eb4--;,,correct ,,mann]4 ,a1 ,b1 ,c ,screws4 #h4 ,! model w\ld require some?+ 9 ! nature ( a v]tical f9 or keel to give ! s5se ( direction4 ,f\r propell]s1 two = lift & two = drift1 w\ld und\bt$ly be a bett] arrangem5t4 ,,footnote3 #dg ,report on ,fir/ ,exhibition ( ,a]onautical ,society ( ,great ,brita91 held at ,cry/al ,palace1 ,june #ahfh4 ,,*apt] ,,xii4 ,,exp]im5tal ,,records4 ,a model fly+ ma*9e be+ a sci5tific inv5tion & n a toy1 e devotee to ! sci5ce %\ld make x 8 or h] bus9ess to keep1 z f> z !y are able1 accurate & sci5tific records4 ,= by su* means z ?is1 & ! mak+ kn[n ( ! same1 c a sci5ce ( model a]oplan+ be f9ally evolv$4 ,! foll[+ exp]im5tal entry =ms1 left purposely blank to be fill$ 9 by ! read]1 are int5d$ z sugge/ions only1 & c1 ( c\rse1 be v>i$ at ! read]'s discretion4 ,:5 y h obta9$ c>efully e/abli%$ data1 d n keep !m to y\rself1 s5d !m along to "o ( ! a]onautical j\rnals4 ,d n ?9k !m valueless2 if c>efully arrang$ !y _c be t1 & may be v valuable4 ,,exp]im5tal ,,data4 ,,=m ,i4 ,column ,head+s3 ,a3 ,model ,b3 ,weight ,c3 ,area ( ,support+ ,surface ,d3 ,aspect ,ratio ,e3 ,av]age ,l5g? ( ,flight 9 ,feet ,f3 ,maximum ,flight ,g3 ,"t ( ,flight1 ,a4 av]age ,h3 ,m4 maximum ,i3 ,k9d & ,direction ( ,w9d ,j3 ,camb] ,k3 ,angle ( ,incl9ation ( ,ma9 ,a](oil to ,l9e ( ,flight ---------------------------------------- --------------- ,a ,b ,c ,d ,e ,f ,g ,h ,i ,j ,k ---------------------------------------- --------------- ,a ,m #a #b #c #d #e #f #g #h #i #aj #aa #ab ---------------------------------------- --------------- ,,=m ,i4--cont9u$4 ,column ,head+s3 ,a3 ,model ,b3 ,weight ( 7,rubb]7 ,motor ,c3 ,k9d ( ,rubb]1 ,flat1 ,squ>e or ,r\nd ,d3 ,l5ght 9 ,in*es & ,numb] ( ,/r&s ,e3 ,numb] ( ,turns ,f3 ,condition at ,end ( ,flight ,g3 ,numb] ( ,propell]s 7,no47 & ,diamet] 7,diam47 ,h3 ,numb] ( ,blades ,i3 ,disc ,area 7,disc,a47 & ,pit* 7,pit*7 ,j3 ,p]c5tage ( ,slip ,k3 ,?ru/ ,l3 ,torque 9 ,in*e-,ounces ---------------------------------------- ----------- ,a ,b ,c ,d ,e ,f ,g ,h ,i ,j ,k ,l ---------------------------------------- ----------- #a #b #c #d #e #f #g #h #i #aj #aa #ab ---------------------------------------- ----------- ,,*apt] ,,xiii4 ,,model ,,fly+ ,,competitions4 #a4 ,f "t to "t fly+ competitions are arrang$ = model a]oplanes4 ,sometimes ^! competitions are entirely op51 b m g5]ally !y are arrang$ by local clubs ) bo? clos$ & op5 ev5ts4 ,no two programmes are probably exactly alike1 b ! foll[+ may be tak5 z fairly repres5tative3-- #a4 ,longe/ flight measur$ 9 a /raight l9e 7sometimes bo? ) & aga9/ ! w9d74#dh #b4 ,/ability 7bo? longitud9al & transv]se74 #c4 ,longe/ glide :5 laun*$ f a giv5 height )\t p[]1 b ) motor & propell] atta*$4 #d4 ,/e]+4 #e4 ,greate/ height4 #f4 ,! be/ all-r\nd model1 includ+1 9 addition to ! above1 excell5ce 9 build+4 ,g5]ally s _m po9ts or m>ks are giv5 = ea* te/1 & ! model ^: aggregate ( po9ts makes ! l>ge/ total w9s ! prize2 or m ?an "o prize may be (f]$-- ,"o = ! longe/ flight4 ,"o = ! swifte/ flight ov] a measur$ di/ance4 ,"o = ! greate/ height4 ,"o = /ability & /e]+4 ,& "o = ! be/ all-r\nd model4 ,! models are divid$ into classes3-- #b4 ,a]o ,models ,association's ,classification1 etc4 ,a4 ,models ( #a sq4 ft4 surface & "u4 ,b4 #b sq4 ft4 ,c4 #d sq4 ft4 ,d4 #h sq4 ft4 ,e4 ov] #h sq4 ft4 ,all surfaces1 :e!r v]tical1 horizontal1 or o!rwise1 to be calculat$ toge!r = ! above classification4 ,all r\nd effici5cy--m>ks or po9ts z p]c5tages3-- ,di/ance #dj p] c5t4 ,/ability #ce ,directional control #ae ,glid+ angle #aj #di ,two prizes3-- ,"o = l5g? ( flight4 ,"o = all-r\nd effici5cy 7m>k$ z above74 ,e competitor to be all[$ ?ree trials 9 ea* competition1 ! be/ only to c\nt4 ,all flights to be measur$ 9 a /raight l9e f ! />t+ to ! l&+ po9t4 ,repairs may be made dur+ ! competition at ! direction ( ! judges4#ej ,!re are "o or two o!r po9ts :]e flights are n made ) & aga9/ ! w9d4 ,! competitors are usually reque/$ to />t _! models f )9 a giv5 circle ( 7say7 six feet diamet]1 & fly !m 9 any direction !y please4 ,glid+ angle means t ! model is all[$ to fall f a height 7say7 ( #bj ft4 ,illu/ration3 ,,fig4 #ec4--,,model ,,design$ ,,& ,,con/ruct$ ,,by ,,! ,,au?or ,,= ,,greate/ ,,height4 ,a v lightly built model ) a v l[ aspect ratio1 & screw giv+ a v p[]ful dynamic ?ru/1 & c>ry+ r a l>ge am\nt ( rubb]4 ,climbs 9 left-h&$ spirals4 ,directional control1 t ! model is laun*$ 9 "s specifi$ direction1 & mu/ pass z ne> z possible ov] "s indicat$ po9t4 ,! models are practically always laun*$ by h&4 #c4 ,^? :o desire to w9 prizes at su* competitions w\ld d well to keep ! foll[+ po9ts well 9 m9d4 #a4 ,! di/ance is always measur$ 9 a /raight l9e4 ,x is absolutely ess5tial t y\r model %\ld be capable ( fly+ 7approximately7 /raight4 ,to see1 z ,i h done1 model aft] model fly q #aej to #bjj y>ds & f9i% )9 #ej y>ds ( ! />t+-po9t 7cr$it$ flight #ej y>ds7 is useless1 & a sev]e /ra9 on "o's temp] & pati5ce4 ,illu/ration3 ,,fig4 #ed4--,,! ,,gamage ,,*all5ge ,,cup4 ,op5 ,competition = longe/ flight4 ,cry/al ,palace1 ,july #bg4 ,won by ,mr4 ,e4,w4 ,tw9+4 ,illu/ration3 ,,fig4 #ee4--,,m$al ,,won ,,by ,,! ,,au?or ,,9 ,,! ,,same ,,competition4 #b4 ,always ent] m ?an "o model1 !re ne>ly always is an entrance fee2 nev] m9d ! extra %ill+ or s4 ,g 9 to w94 #c4 ,x is n necess>y t ^! models %\ld be replicas ( "o ano!r4 ,on "s days a light fabric-cov]$ model might /& ! be/ *ance2 on ano!r day1 a swift fly+ wood5 or metal a](oil4 ,aga9/ ! w9d ! latt] h an imm5se advantage2 also if ! day be a gu/y "o4#ea #d4 ,always make x a po9t ( arriv+ e>ly on ! gr\nd1 s t y c make "s trial flights be=eh&4 ,e gr\nd has its local peculi>ities ( air curr5ts1 etc4 #e4 ,always be ready 9 "t1 or y may be disqualifi$4 ,if y are fly+ a tw9-screw model use a special w9d]1 s t bo? propell]s are w\nd up at ! same "t1 & take a compet5t fri5d ) y z assi/ant4 #f4 ,= all-r\nd effici5cy no?+ b a good all-r\nd model1 :i* c be absolutely reli$ on to make a doz5 7approximately7 equival5t flights1 is any good4 #g4 ,9 an op5 di/ance competition1 unless y h a model :i* y c rely on to make a m9imum flight ( #bjj y>ds1 d n ent] unless y "k = c]ta9 t none ( ! crack fly]s w be pres5t4 #h4 ,d n neglect ! smalle/ detail likely to lead to success2 be prep>$ ) sp>e p>ts1 extra rubb]1 "o or two h&y tools1 wire1 ?read1 etc4 ,be=e a lecture1 t pr9ce ( exp]im5tali/s1 ,f>aday1 0 always c>eful to see t ! /opp]s ( all ! bottles 7 loose1 s t !re %\ld be no delay or mi%ap4 #i4 ,if ! rat+ ( ! model be by weight 7#a oz41 #b oz41 #d oz41 etc47 & n area1 use a model weigh+ f #aj oz4 to a p\nd4 #aj4 ,if !re is a greate/ height prize1 a helicopt] model %\ld w9 x4#eb 7,! writ] has atta9$ an altitude ( betwe5 ?ree & f\r hundr$ feet ) su*47 ,! altitude 0 arriv$ at by obs]vation1 n guesswork4 #aa4 ,x is mo/ important t y\r model %\ld be able to l& )\t damage1 &1 z f> z possible1 on an ev5 keel2 d n omit "s =m ( skid or %ock-absorb] ) ! idea ( sav+ weight1 m especially if y\r model be a biplane1 or ! numb] ( flights may be re/rict$ to ! numb] "o4 #ab4 ,s9ce ! be/ glid+ angle & fly+ angle are n ! same1 be+1 say1 #g 9 ! =m] case & #a-c1 say1 9 ! latt]1 an adju/able angle might 9 "s cases be advantage\s4 #ac4 ,nev] turn up at a competition ) a model only j f9i%$ & practically unte/$ :i* y h fl[n only on ! morn+ ( ! competition1 us+ old rubb] & w9d+ to #ejj turns2 result1 a flight ( #bej y>ds1 say4 ,arriv$ on ! competition gr\nd y put on new rubb] & w9d to #gej turns1 & expect a flight ( a qu>t] ( a mile at lea/2 result #gj y>ds1 measur$ 9 a /raight l9e f ! />t+-po9t4 #ad4 ,directional control is ! mo/ difficult problem to ov]come ) any degree ( success "u all adv]se conditions1 & #ae p] c5t41 9 ! writ]'s op9ion1 is f> too l[ a p]c5tage2 by directional ,i include fly+ 9 a /raight l9e2 p]sonally ,i w\ld m>k = all-r\nd effici5cy3 7,a7 di/ance & /ability1 #ej p] c5t42 7,b7 directional control1 #cj p] c5t42 7,c7 duration ( flight1 #bj p] c5t4 ,9 ,a ! competitor w\ld laun* 8 model 9 any direction2 9 ,b z direct$ by ! judges4 ,no sep>ate flights requir$ = ,c4 ,,footnotes3 #dh ,! bett] way1 und\bt$ly1 is to all[ ! competitor to *oose 8 direction1 ! />t+ circle only to be fix$4 #di ,or #aj p] c5t4 = duration ( flight4 #ej ,9 ano!r competition1 held "u ! rules & regulations ( ! ,kite & ,model ,a]oplane ,association = ! be/ all-r\nd model1 op5 to ! _w1 = ma*9es n "u #b sq4 ft4 ( surface1 ! te/s 7#ej m>ks = ea*7 73--,a4 ,longe/ flight 9 a /raight l9e4 ,b4 ,circul> flight to ! "r4 ,c4 ,circul> flight to ! left4 ,d4 ,/ability & l&+ aft] a flight4 ,e4 ,excell5ce 9 build+ ( ! model4 #ea ,on ! assumption t ! model w fly /raight4 #eb ,if p]mitt$ to ent]2 if n see ,fig4 #ec4 ,,*apt] ,,xiv4 ,,useful ,,notes1 ,,tables1 ,,=mul1 ,,etc4 #a4 ,,comp>ative ,,velocities4 ,miles p] hr4 ,feet p] sec4 ,metres p] sec4 #aj #adg #ddgj #ae #bb #fgje #bj #bid #hidj #be #cfg #aaagf #cj #dd #acdaa #ce #eac #aefdf #b4 ,a metre #cicgjgi in*es4 ,9 ord] to conv]t3-- ,metres into in*es multiply by #cicg feet #cbh y>ds #aji miles #jjjjfbad ,miles p] h\r into ft4 p] m94 multiply by #hhj m94 sec4 #hhj hr4 into kilometres p] hr4 #afjic metres p] sec4 #jddgjb ,p\nds into grammes multiply by #deceic kilogrammes #jdecf #h4 ,total surface ( a cyl9d] circumf]5ce ( base height #b area ( base4 ,area ( a circle squ>e ( diamet] #jghed4 ,area ( a circle squ>e ( rad4 #cadaei4 ,area ( an ellipse product ( axes #jghed4 ,circumf]5ce ( a circle diamet] #cadaei4 ,solidity ( a cyl9d] height area ( base4 ,area ( a circul> r+ sum ( diamet]s diff]5ce ( diamet]s #jghed4 ,= ! area ( a sector ( a circle ! rule is3--,z #cfj 3 numb] ( degrees 9 ! angle ( ! sector 33 area ( ! sector 3 area ( circle4 ,to f9d ! area ( a segm5t less ?an a semicircle3--,f9d ! area ( ! sector :i* has ! same arc1 & subtract ! area ( ! triangle =m$ by ! radii & ! *ord4 ,! areas ( correspond+ figures are z ! squ>es ( correspond+ l5g?s4 #d4 #a mile #afji kilometres4 #a kilometre #ajic y>ds4 #a oz4 #bhce grammes4 #a lb4 #decei #a lb4 #jdec kilogrammes4 #bh lb4 #abg #aab lb4 #ejh #bbdj lb4 #ajaf #a kilogram #bbjdf lb4 #a gram #jjjbb lb4 #a sq4 94 #fde sq4 millimetres4 #a sq4 ft4 #jjibi sq4 metres4 #a sq4 y>d #jhcf #a sq4 metre #ajgfd sq4 ft4 #e4 ,"o atmosph]e #adg lb4 p] sq4 94 #baaf lb4 p] sq4 ft4 #gfj millimetres ( m]cury4 ,a column ( wat] #bc ft4 high corresponds to a pressure ( #a lb4 p] sq4 94 #a ,h4,p4 #cc1jjj ft4-lb4 p] m94 #gdf watts4 ,volts amp]es watts4 pi #cadaf4 g #cbahb ft4 p] sec4 at ,london4 #f4 ,,table ,,( ,,equival5t ,,incl9ations4 ,rise4 ,angle 9 ,degs4 #a 9 #cj #aia #a #be #bbi #a #bj #bhg #a #ah #cah #a #af #ceh #a #ad #dji #a #ab #dgh #a #aj #egc #a #i #fch #a #h #gah #a #g #hbb #a #f #if #a #e #aaec #a #d #addh #a #c #aide #a #b #cjjj #a squ>e root#b #dejj #g4 ,,table ,,( ,,sk9 ,,friction4 ,p] sq4 ft4 = v>i\s spe$s & surface l5g?s4 ---------------------------------------- ---------------------------- ,velocity ( ,w9d #a ft4 ,plane #b ft4 ,plane #d ft4 ,plane #h ft4 ,plane ---------------------------------------- ---------------------------- #aj #jjaab #jjaje #jjaja #jjjifg #ae #jjbcg #jjbbf #jjbae #jjbje #bj #jjdjb #jjchd #jjcfe #jjcdi #be #jjfjf #jjegi #jjeea #jjebg #cj #jjhej #jjhaj #jjggb #jjgcf #ce #jaacj #jajh #jajc #jjih ---------------------------------------- ---------------------------- ,?is table is bas$ on ,dr4 ,zahm's exp]im5ts & ! equation f #jjjjjjgghl-#jjgv#ahe ,:]e f sk9 friction p] sq4 ft42 l l5g? ( surface2 v velocity 9 feet p] second4 ,9 a biplane model ! head resi/ance is probably f twelve to f\rte5 times ! sk9 friction2 9 a rac+ monoplane f six to eight times4 #h4 ,,table ,i4--7,,metals74 ---------------------------------------- ---------------- ,mat]ial ,specific ,ela/icity ,e,a ,t5acity ,gravity p] sq4 94 ---------------------------------------- ---------------- ,magnesium #agd #bb1jjj- #cb1jjj ,magnalium,b #bd-beg #ajb ,alum9ium- ,copp],c #bhb #ed1ggc ,alum9ium #bf #aaa #bf1ece ,iron #gg 7ab\t7 #bi #ed1jjj ,/eel #gh 7ab\t7 #cb #ajj1jjj ,brass #gh-hd #ae #ag1ejj ,copp] #hh #cf #cc1jjj ,mild ,/eel #gh #cj #fj1jjj ---------------------------------------- ---------------- ,a ,e 9 millions ( lb4 p] sq4 94 ,b ,magnalium is an alloy ( magnesium & alum9ium4 ,c ,alum9ium #id p] c5t41 copp] #f p] c5t4 7! be/ p]c5tage71 a #f p] c5t4 alloy !reby d\bles ! t5acity ( pure alum9ium ) b #e p] c5t4 increase ( d5sity4 ---------------------------------------- ---------------- #i4 ,,table ,,ii4--,,w9d ,,pressures4 p kv4 k coeffici5t 7mean value tak57 #jjc 7miles p] h\r7 #jjjaf ft4 p] second4 p pressure 9 lb4 p] sq4 ft4 v velocity ( w9d4 ,miles p] hr4 ,ft4 p] sec4 ,lb4 p] sq4 ft4 #aj #adg #jcjj #ab #agf #jdcb #ad #bje #jehh #af #bce #jgfh #ah #bfd #jigb #bj #bice #abjj #be #cfg #ahge #cj #dci #bgjj #ce #eac #cfge #aj4 ,repres5t+ normal pressure on a plane surface by #a2 pressure on a rod 7r\nd section7 is #jf2 on a symmetrical elliptic cross section 7axes #b3a7 is #jb 7approx474 ,simil> %ape1 b axes #f3a1 & edges %>p5$ 7see *4 ii41 #e71 is only #jje1 or #a_/bj1 & = ! body ( m9imum resi/ance 7see *4 ii41 #d7 ab\t #a_/bd4 #aa4 ,,table ,,iii4--,,lift ,,& ,,drift4 ,on a well %ap$ a]ocurve or correctly design$ camb]$ surface4 ,aspect ratio #de4 ,incl9ation4 ,ratio ,lift to ,drift4 #j #ai3a #bhg #ae3a #ceh #af3a #dji #ad3a #dgh #ab3a #egc #if3a #gah #gi3a ,w9d velocity #dj miles p] h\r4 7,! above d$uc$ f "s exp]im5ts ( ,sir ,hiram ,maxim47 ,at a velocity ( #cj miles an h\r a good a]ocurve %\ld lift #ba oz4 to #bd oz4 p] sq4 ft4 #ab4 ,,table ,,iv4--,,lift ,,& ,,drift4 ,on a plane a](oil4 ,n ,p7#b s9 alpha_/#a s9 alpha7 ,incl9ation4 ,ratio ,lift to ,drift4 #a #ehc3a #b #bib3a #c #aic3a #d #adc3a #e #aad3a #f #ie3a #g #hj3a #h #gj3a #i #fc3a #aj #eg3a ,p #bkd ,,av s9 alpha4 ,a useful =mula = a s+le plane surface4 ,p pressure support+ ! plane 9 p\nds p] squ>e foot1 k a con/ant #jjjc 9 miles p] h\r1 d ! d5sity ( ! air4 ,a ! area ( ! plane1 ,v relative velocity ( translation ?r\gh ! air1 & alpha ! angle ( flight4 ,transpos+ we h ,,av ,p_/7#bkd s9 alpha7 ,if ,p & alpha are con/ants2 !n ,,av a con/ant or area is inv]sely z velocity squ>$4 ,increase ( velocity mean+ dim9i%$ support+ surface 7& s f> z support+ surface goes71 dim9i%$ resi/ance & sk9 friction4 ,x mu/ be rememb]$1 h[ev]1 t :ile ! "w ( su/5tation dim9i%es ) ! spe$1 ! "w ( p5etration v>ies z ! cube ( ! spe$4 #ac4 ,,table ,v4--,,timb]4 ,column ,head+s3 ,a4 ,mat]ial ,b4 ,specific ,gravity ,c4 ,weight p] ,cub4 ,ft4 9 ,lb4 ,d4 ,/r5g? p] ,sq4 ,94 9 ,lb4 ,e4 ,ultimate ,break+ ,load 7,lb47 span #a' x #a x #a ,f4 ,relative ,resili5ce 9 ,b5d+ ,g4 ,modulus ( ,ela/icity 9 millions ( ,lb4 p] ,sq4 ,94 = ,b5d+ ,h4 ,relative ,value4 ,b5d+ ,/r5g? comp>$ ) ,weight ---------------------------------------- --------------------- ,a ,b ,c ,d ,e ,f ,g ,h ---------------------------------------- --------------------- ,a% #gi #dc-eb #ad1jjj-ag1jjj #fbb #dfi #aee #acj ,bamboo #be;,a #fcjjec #cjg #cbj ,bee* #fi #dc #aj1jjj-ab1jjj #hej #afe #aih ,bir* #ga #de #ae1jjj #eej #cbh #abb ,box #abh #hj #bj1jjj-bc1jjj #hae #ajb ,cork #bd #ae ,fir 7,norway ,spruce7 #ea #cb #i1jjj-aa1jjj #dej #cja #agj #adj ,am]ican ,hickory #di #aa1jjj #hjj #cdg #bdj #afc ,honduras ,mahogany #ef #ce #bj1jjj #gej #cdj #afj #bad ,maple #fh #dd #aj1fjj #gej #agj ,am]ican ,:ite ,p9e #db #be #aa1hjj #dej #bcg #aci #ahj ,lomb>dy ,popl> #bd #g1jjj #eej #bhi #jggbbi ,am]ican ,yell[ ,popl> #dd #aj1jjj #cfc #adj ,sat9wood #if #fj #a1jcc #agb ,spruce #ej #ca #ab1djj #dej #ade ,tubul> ,a%1 t #a_/h d #dg #cej #aee ---------------------------------------- --------------------- t ?ickness3 d diamet]4 ,a ,giv5 else:]e z #ee & #bb1ejj 7t #a_/c;d71 evid5tly reg>d$ z solid4 #ad4--;,=mula connect+ ! ,weight ,lift$ 9 ,p\nds p] ,squ>e ,foot & ! ,velocity4--,! empirical =mula ,w 7,v,c7_/g ,:]e ,w weight lift$ 9 lb4 p] sq4 ft4 ,v velocity 9 ft4 p] sec4 ,c a con/ant #jjbe4 g #cbb1 or #cb approx4 may be us$ = a ?or\ghly effici5t model4 ,?is gives 7approximately7 #a lb4 p] sq4 ft4 lift at #be miles an h\r4 #ba oz4 #cj #f oz4 #ae #d oz4 #ab #bg oz4 #aj ,rememb] ! results "w out 9 feet p] second4 ,to conv]t 7approximately7 into miles p] h\r multiply by #b_/c4 #ae4 ,=mula connect+ ,models ( ,simil> ,design1 b ,diff]5t ,weights4 ,d proportional to squ>e root,w4 or 9 models ( simil> design ! di/ances fl[n are proportional to ! squ>e roots ( ! weights4 7,d]iv$ f data obta9$ f ,cl>ke's fly]s47 ,= models f #a oz4 to #bd-cj oz4 ! =mula appe>s to hold v well4 ,= heavi] models x appe>s to give ! heavi] model r too great a di/ance4 ,s9ce ?is 0 d$uc$ a #a oz4 ,cl>ke model ( some:at simil> design b long] rubb] motor has fl[n #gej ft4 at lea/2 x is true ! design is n1 /rictly speak+1 simil>1 b n too mu* reliance mu/ be plac$ on ! above4 ,! record = a #a oz4 model to date is ov] #cjj y>ds 7) ! w9d1 ( c\rse71 say #gej ft4 9 calm air4 #af4 ,p[] & ,spe$4--,! foll[+ =mula1 giv5 by ,mr4 ,l4 ,bl9 ,desbl$s1 betwe5 ^! is-- ,w_/,w#j 7#cv#j7_/7dv7 7v_/v#j74 ,:]e v#j spe$ ( m9imum p[] ,w#j "w done at spe$ v#j4 ,w "w done at spe$ v4 ,mak+ v #bv#j1 i4e4 d\bl+ ! spe$ ( m9imum p[]1 & sub/itut+1 we h f9ally ,w 7#b-c_/h7,w#j i4e4 ! spe$ ( an a]oplane c be d\bl$ by us+ a p[] #b-c_/h times z great z ! orig9al "o4 ,! spe$ ( m9imum p[] be+ ! spe$ at :i* ! a]oplane mu/ travel = ! m9imum exp5diture ( p[]4 #ag4 ,! ?ru/ ( ! propell] has evid5tly to balance ! ,a]odynamic resi/ance ,r ,! head resi/ance 7includ+ sk9 friction7 ,s ,n[ accord+ to ,r5>d's !orem1 ! p[] absorb$ by ,r ,s is a m9imum :5 ,s ,r_/#c4 ,hav+ built a model1 !n1 9 :i* ! total resi/ance 7#d_/c7,r4 ,?is is ! ?ru/ :i* ! propell] %\ld be design$ to give4 ,n[ suppos+ ! propell]'s effici5cy to be #hj p] c5t41 !n ,p--! m9imum propulsion p[] 7#d_/c7,r #ajj_/hj #ajj_/ge v4 ,:]e #be p] c5t4 is ! slip ( ! screw1 v ! velocity ( ! a]oplane4 #ah4 ,to det]m9e exp]im5tally ! ,/atic ,?ru/ ( a ,propell]4--,useful = models int5d$ to raise !mselves f ! gr\nd "u _! own p[]1 & = helicopt]s4 ,! easie/ way to d ?is is z foll[s3 ,m\nt ! propell] on ! %aft ( an electric motor1 ( suffici5t p[] to give ! propell] #ajjj to #aejj revolutions p] m9ute2 a suitable accumulator or o!r s\rce ( electric en]gy w be requir$1 a spe$omet] or spe$ c\nt]1 also a voltmet] & ammet]4 ,place ! motor 9 a pair ( scales or on a suitable spr+ balance 7! =m] is pref]able71 ! axis ( ! motor v]tical1 ) ! propell] atta*$4 ,rotate ! propell] s t ! air curr5t is driv5 upw>ds4 ,:5 ! correct spe$ 7z indicat$ by ! spe$ c\nt]7 has be5 atta9$1 notice ! diff]5ce 9 ! read+s if a spr+ balance be us$1 or1 if a pair ( scales1 place weights 9 ! scale pan until ! d[nw>d ?ru/ ( ! propell] is exactly balanc$4 ,?is gives y ! ?ru/ 9 ounces or p\nds4 ,note c>efully ! voltage & amp]age1 suppos+ x is #h volts & #aj amp]es #hj watts4 ,remove ! propell] & note ! volts & amp]es consum$ to run ! motor alone1 i4e4 to excite itself1 & ov]come friction & air resi/ance2 suppose ?is to be #h volts & #b amp]es #af2 ! increas$ load :5 ! propell] is on is !re=e #hj - #af #fd watts4 ,all ?is increas$ p[] is n1 h[ev]1 exp5d$ on ! propell]4 ,! lo/ p[] 9 ! motor increases z ,c,r4 ,r resi/ance ( armature & ,c curr5t4 ,if we d$uct #aj p] c5t4 = ?is !n ! propell] is actually driv5 by #ef watts4 ,n[ #gdf watts #a h4p4 !re=e #ef_/gdf #a_/ac h4p4 approx4 at ! obs]v$ numb] ( revolutions p] m9ute4 #ai4 ,n4,b4--,! h4p4 requir$ to drive a propell] v>ies z ! cube ( ! revolutions4 ,pro(4--,d\ble ! spe$ ( ! screw1 !n x /rikes ! air twice z h>d2 x also /rikes twice z mu* air1 & ! motor has to g twice z fa/ to d x4 #bj4 ,to comp>e "o model ) ano!r ! =mula ,weight velocity 79 ft4 p] sec47_/horse-p[] is sometimes useful4 #ba4 ,a ,horse-p[] is #cc1jjj lb4 rais$ "o foot 9 "o m9ute1 or #eej lb4 "o foot 9 "o second4 ,a clockwork spr+ rais$ #a lb4 ?r\gh #d ft4 9 #c seconds4 ,:at is its h4p48 #a lb4 ?r\gh #d ft4 9 #c seconds is #a lb4 #ij ft4 #a m9ute4 !re=e ,"w done is #ij ft4-lb4 #ij_/ccjjj #jjjbgbg h4p4 ,! weight ( ! spr+ 0 #f oz4 7?is is tak5 f an actual exp]im5t71 i4e4 ?is motor develops p[] at ! rate ( #jjjbgbg h4p4 = #c seconds only4 #bb4 ,to ,asc]ta9 ! ,h4,p4 ( a ,rubb] ,motor4 ,suppos+ a propell] w\nd up to #bej turns to run d[n 9 #ae seconds1 i4e4 at a mean spe$ ( #abjj revolutions p] m9ute or #bj p] second4 ,suppose ! mean ?ru/ to be #b oz41 & let ! pit* ( ! propell] be #a foot4 ,!n ! numb] ( foot-p\nds ( en]gy develop$ 7#b oz4 #abjj revols4 #a ft4 7pit*77 _/ #af oz4 #aej ft4-lb4 p] m9ute4 ,b ! rubb] motor runs d[n 9 #ae seconds4 !re=e ,en]gy really develop$ is 7#aej #ae7 _/ #fj #cge ft4-lb4 ,! motor develops p[] at rate ( #aej_/ccjjj #jjjdede h4p41 b = #ae seconds only4 #bc4 ,foot-p\nds ( ,en]gy 9 a ,giv5 ,weight ( ,rubb] 7exp]im5tal det]m9ation (74 ,l5g? ( rubb] #cf yds4 ,weight #b-g_/af oz4 ,numb] ( turns #bjj4 #ab oz4 7 rais$ #ai ft4 9 #e seconds4 i4e4 lb4 0 rais$ #ai #ab ft4 9 #a m9ute4 i4e4 #a lb4 0 rais$ #ai #c #c ft4 9 #a m9ute4 #aga ft4 9 #a m9ute4 i4e4 #aga ft4-lb4 ( en]gy p] m9ute4 ,b actual "t 0 #e seconds4 !re=e ,actual en]gy develop$ by #b-g_/af oz4 ( rubb] ( #cf y>ds1 i4e4 #cf /r&s #a y>d ea* at #bjj turns is #aga_/ab ft4-lb4 #ad ft4-lb4 ,?is all[s no?+ = friction or turn+ ! axle on :i* ! cord 0 w\nd4 ,ball be>+s 7 us$2 b ! rubb] 0 n new & tw5ty turns 7 /ill unw\nd at ! end ( ! exp]im5t4 ,n[ all[+ = friction1 etc4 be+ ! same z on an actual model1 we c take ( a ft4-lb4 = ! unw\nd am\nt & e/imate ! total en]gy z #ae ft4-lb4 z a m9imum4 ,! en]gy actually develop$ be+ at ! rate ( #jjjee h4p41 or #a_/bjj ( a h4p4 if suppos$ uni=m4 #bd4 ,! actual en]gy d]ivable f #a lb4 weight ( rubb] is /at$ to be #cjj ft4-lb4 ,on ?is basis #b-g_/af oz4 %\ld be capable ( giv+ #deg ft4-lb4 ( en]gy1 i4e4 ?ree times ! am\nt giv5 above4 ,n[ ! motor-rubb] n lubricat$ 0 only giv5 #bjj turns--lubricat$ #djj c\ld h be5 giv5 x1 #fjj probably be=e rupture--& ! en]gy !n d]ivable w\ld c]ta9ly h be5 approximat+ to #de ft4-lb41 i4e4 #cfbe4 ,n[ on ! basis ( #cjj ft4-lb4 p] lb4 a weight ( oz4 7! am\nt ( rubb] c>ri$ 9 "o-ounc]s7 gives #i ft4-lb4 ( en]gy4 ,n[ assum+ ! glid+ angle 7includ+ weight ( propell]s7 to be #a 9 #h2 a p]fectly effici5t model %\ld be capable ( fly+ eight times z great a di/ance 9 a horizontal direction z ! en]gy 9 ! rubb] motor w\ld lift x v]tically4 ,n[ #i ft4-lb4 ( en]gy w lift #a oz4 #aed ft4 ,!re=e !oretically x w drive x a di/ance 79 y>ds7 ( 7#h #aed7_/c #dajf y>ds4 ,n[ ! greate/ di/ance t a #a oz4 model has fl[n 9 p]fectly calm air 7:i* nev] exi/s7 is n kn[n4 ,fly+ ) ! w9d #ejj y>ds is claim$4 ,admitt+ ?is :at all[ance %all we make = ! w9d2 suppos+ we d$uct half ?is1 viz4 #bej y>ds4 ,!n1 on ?is assumption1 ! effici5cy ( ?is "o ounc] works out 79 p]fectly /ill air7 at #fa p] c5t4 ,! glid+ angle assumption ( #a 9 #h is r a high "o1 possibly too high2 all ! writ] desires to %[ is ! me?od ( work+ out4 ,mr4 ,t4,w4,k4 ,cl>ke in=ms me t 9 8 "o-ounc]s ! glid+ angle is ab\t #a 9 #e4 #be4 ,to ,te/ ,diff]5t ,motors or ,diff]5t ,p[]s ( ! ,same ,k9d ( ,motor4--,te/ !m on ! same ma*9e1 & d n use diff]5t motors or diff]5t p[]s on diff]5t ma*9es4 #bf4 ,effici5cy ( a ,model4--,! effici5cy ( a model dep5ds on ! weight c>ri$ p] h4p4 #bg4 ,effici5cy ( ,design4--,! effici5cy ( "s p>ticul> design dep5ds on ! am\nt ( support+ surface necess>y at a giv5 spe$4 #bh4 ,naph?a ,eng9es1 t is1 eng9es made on ! pr9ciple ( ! /eam eng9e1 b :i* use a light _s ( petrol or simil> ag5t 9 _! g5]ator in/ead ( wat] ) ! same am\nt ( heat1 w develop twice z mu* en]gy z 9 ! case ( ! ord9>y /eam eng9e4 #bi4,petrol ,motors4 ,horse-p[]4 ,no4 ( ,cyl9d]s4 ,weight4 ,s+le #d lb4 to #f #a ,d\ble #i #cj4 ,! ,horse-p[] ( ,model ,petrol ,motors4--,=mula = rat+ ( ! above4 7,r4,p4,m4 revolutions p] m9ute47 ,h4,p4 77,bore7 /roke no4 ( cyl9d]s ,r4,p4,m47_/#ab1jjj ,if ! "r-h& side ( ! equation gives a less h4p4 ?an t /at$ = "s p>ticul> motor1 !n x foll[s t ! h4p4 ( ! motor has be5 ov]-e/imat$4 ,illu/ration3 ,,fig4 #ef4 #cj;,a4 ,relation betwe5 ,/atic ,?ru/ ( ,propell] & ,total ,weight ( ,model4--,! ?ru/ %\ld be approx4 ( ! weight4 #ca4 ,h[ to f9d ! ,height ( an ,inaccessible ,object by ,means ( ,?ree ,obs]vations tak5 on ! ,gr\nd 7suppos$ flat7 9 ! same ,/raight ,l9e4--,let ,a1 ,c1 ,b be ! angul> elevations ( ! object ,d1 z se5 f ^! po9ts1 tak5 9 ! same /raight l9e4 ,let ! di/ances ,b ,c1 ,c ,a & ,a ,b be a1 b1 c respectively4 ,& let requir$ height ,p ,d h2 !n by trigonometry we h 7see ,fig4 #ef7 h abc_/7a cot,a - c cot,c b cot,b74 #cb4 ,=mula = calculat+ ! ,i4,h4,p4 7indicat$ horse-p[]7 ( a s+le-cyl9d] d\ble-act+ /eam-eng9e4 ,indicat$ h4p4 means ! h4p4 actually ex]t$ by ! /eam 9 ! cyl9d] )\t tak+ into acc\nt eng9e friction4 ,brake h4p4 or effective h4p4 is ! actual h4p4 deliv]$ by ! crank %aft ( ! eng9e4 ,i4,h4,p4 7#b ,s ,r ,a ,p7_/#cc1jjj4 ,:]e ,s /roke 9 feet4 ,r revolutions p] m9ute4 ,a area ( pi/on 9 in*es4 ,p mean pressure 9 lb4 ex]t$ p] sq4 94 on ! pi/on4 ,! only difficulty is ! mean effective pressure2 ?is c be f\nd approximately by ! foll[+ rule & accompany+ table4 ,,table ,,vi4 ---------------------------------------- ---------------- ,cut-(f ,con/ant ,cut-(f ,con/ant ,cut-(f ,con/ant ---------------------------------------- ---------------- #a_/f #eff #c_/h #gga #b_/c #iag #a_/e #fjc #d #ghi #g #ibf #a_/d #fei #a_/b #hdg #c_/d #icg #c #gjh #f #hie #h #idd #a_/c #gdc #e_/h #ijd #g_/h #iea ---------------------------------------- ---------------- ,rule4--,add #adg to gauge pressure ( boil]1 ?is giv+ 'absolute /eam pressure1' multiply ?is sum by ! numb] opposite ! fraction repres5t+ ! po9t ( cut-(f 9 ! cyl9d] 9 accompany+ table4 ,subtract #ag f ! product & multiply ! rema9d] by #ji4 ,! result w be v ne>ly ! ,m4,e4,p4 7,r4,m4 de ,vigni]47 ,,footnote3 #ec ,giv5 else:]e z #ee & #bb1ejj 7t #a_/c d71 evid5tly reg>d$ z solid4 ,,app5dix ,a4 ,,"s ,,models ,,:i* ,,h ,,won ,,m$als ,,at ,,op5 ,,competitions4 ,illu/ration3 ,,fig4 #eg4--,,! ,g4,p4,b4 ,,smi? ,,model4 ,! model %[n 9 ,fig4 #eg has won m competition m$als ?an any o!r4 ,x is a ?or\ghly well design$#ed & well con/ruct$ model4 ,orig9ally a v sl[ fly]1 ! design has be5 simplifi$1 & al?\gh by no means a fa/ fly]1 its spe$ has be5 mu* accel]at$4 ,orig9ally a "o-propell] ma*9e1 x has latt]ly be5 fitt$ ) tw9 propell]s1 ) ! idea ( obta9+ m directional control2 b 9 ! writ]'s op9ion1 speak+ f p]sonal obs]vation1 ) b little1 if any1 success4 ,! /e]+ ( ! model is effect$ by cant+ ! elevator4 ,orig9ally ! ma*9e _h ail]ons = ! purpose1 b ^! 7 remov$ ow+1 ,i und]/&1 to _! ret>d+ ! spe$ ( ! ma*9e4 ,9 e competition 9 :i* ?is ma*9e has be5 ent]$ x has always ga9$ v high m>ks = /ability4 ,illu/ration3 ,,fig4 #eh4--,,! ,,gordon-,,jones ,,dih$ral ,,biplane4 ,up to ! "t ( writ+ x has n be5 provid$ ) any?+ 9 ! nature ( f9s or rudd]4 ,fig4 #eh is a biplane v mu* aft] ! type ( ! model j allud$ to1 b ! "o /raight & "o curv$ a](oil surfaces are "h replac$ by two p>allel a](oils set on a dih$ral angle4 ,! l>ge size ( ! propell] %\ld be not$2 ) ?is ! writ] is 9 complete agreem5t4 ,he has n un=tunately se5 ?is model 9 actual flight4 ,! sci5tifically design$ & beautifully made models illu/rat$ 9 ,fig4 #ei are s well kn[n t any rem>ks on !m appe> sup]flu\s4 ,_! effici5cy1 s f> z _! support+ area goes1 is ( ! highe/1 z mu* z #ba oz4 p] squ>e foot hav+ be5 c>ri$4 ,illu/ration3 ,,fig4 #ei4--,,messrs4 ,t4,w4,k4 ,,cl>ke ,,& ,,co4',s ,,model ,,fly]s4 ,= illu/rations1 etc41 ( ! ,flem+-,williams model1 see *4 v41 #bc4 7,fig4 #fj47 ,?is is ano!r well-con/ruct$ & effici5t model1 ! %ape & "* ( ! a](oil surfaces mu* resembl+ ^? ( ! ,fr5* toy monoplane ,,al-,,ma 7see #d1 *4 vii471 b !y are support$ & held 9 position by q a diff]5t me?od1 a neat little device enabl+ ! front plane to become p>tly deta*$ on collision ) any ob/acle4 ,! model is provid$ ) a keel 7bel[ ! c5tre ( gravity71 & rudd] = /e]+2 9 fact1 ?is ma*9e especially claims c]ta9ty ( directional control4 ,! writ] has se5 a numb] ( flights by ?is model1 b x exp]i5ces1 l o!r models1 ! greate/ difficulty 9 keep+ /raight if ! conditions be adv]se4 ,! model :i* w d ?is is1 9 8 op9ion1 yet to be evolv$4 ,! small size ( ! propell]s is1 ( c\rse1 9 total disagreem5t ) ! au?or's ideas4 ,all ! same1 ! model is 9 _m respects an excell5t "o1 & has fl[n ov] #cjj y>ds at ! "t ( writ+4 ,illu/ration3 ,,fig4 #fj4--,,! ,,d+ ,,say]s ,,monoplane4 ,m ?an a ye> ago ! au?or made a numb] ( models ) triangul>-%ap$ a](oils1 us+ umbrella ribs = ! lead+ edge & /eel piano wire = ! trail+1 b has latt]ly us$ a](oils ( ! elongat$ ellipse %ape4 ,fig4 #fa is an illu/ration ( "o ( ! au?or's late/ models :i* won a ,bronze ,m$al at ! ,long ,di/ance ,op5 ,competition1 held at ! ,cry/al ,palace on ,july #bg1 #aiaj1 ! l>ge/ & mo/ ke5ly conte/$ competition held up to t date4 ,! be/ & /raighte/ flight aga9/ ! w9d 0 made by ?is model4 ,on ! morn+ ( ! competition a flight ( ab\t #cbj y>ds 7measur$ 9 a /raight l9e7 0 made on ,mit*am ,common1 ! model be+ laun*$ aga9/ ! w9d s z to ga9 altitude1 & !n fly+ away ) ! breeze beh9d ! writ]4 ,duration ( flight #ej seconds4 ,! foll[+ are ! *ief p>ticul>s ( ! model3--,weight1 #g oz4 ,area ( support+ surface1 #a-a_/c sq4 ft4 ,total l5g?1 #d ft4 ,span ( ma9 a](oil1 #be 94 ,aspect ratio1 #d 3 #a4 ,diamet] ( propell]1 #ad 94 ,two /r& ge>$ rubb] motor1 c>ry+ altoge!r #bh /r&s ( #a_/af squ>e rubb] cord #dc 94 long4 ,! propell] 0 orig9ally a ,v5na1 b ) ! weight r$uc$ by "o-?ird1 & consid]able alt]ation made 9 its c5tral cont\rs4 ,! front skid ( /eel pian(orte wire1 ! re> ( jo9tless cane wire tipp$2 ! re> skid 0 a necessity 9 ord] to protect ! delicate ge>+ me*anism1 ! weight ( :i* 0 r$uc$ to a m9imum4 ,illu/ration3 ,,fig4 #fa4--,,! ,,au?or',s ,,gras%opp] ,,model4 ,! v l>ge diamet] ( ! propell] %\ld be not$1 be+ #ef p] c5t4 ( ! span4 ,! f91 high above ! c5tre ( gravity1 0 s plac$ = transv]se /ability & direction4 ,at ! re> ( ! f9 0 a rudd]4 ,! small am\nt ( rubb] c>ri$ 7= a long di/ance ma*9e7 %\ld also be not$1 especially :5 all[+ = friction 9 ge>+1 etc4 ,! c5tral rod 0 a p5ny bamboo cane1 ! l>ge a](oil ( jo9tless cane & ,h>t's fabric1 & ! front a](oil ( /eel wire surfac$ ) ! same mat]ial4 ,,london3 ,,pr9t$ ,,by ,,william ,,cl[es ,,& ,,sons1 ,,limit$1 ,,great ,,w9dmill ,,/reet1 ,w41 ,,& ,,duke ,,/reet1 ,,/am=d ,,/reet1 ,s4,e4 ,,footnote3 #ed ,! design is pat5t$4 ,octob]1 #aiaj ,a ,,%ort ,,li/ ,,( ,,sci5tific ,,books ,,publi%$ ,,& ,,sold ,,by ,e4 ,f4,n4 ,,spon1 ,limit$1 #eg ,haym>ket1 ,london1 ,s4,w4 ,,sole ,,engli% ,,ag5ts = ! ,books (-- ,,myron ,c4 ,,cl>k1 ,,new ,,york ,,! ,,bus9ess ,,code ,,company1 ,,*icago ,,spon ,,*amb]la91 ,,new ,,york ,,page ,,a]onautics #b ,,agriculture #b ,,ar*itecture #c ,,artill]y #e ,,bridges ,,& ,,ro(s #e ,,build+ #c ,,cem5t ,,& ,,concrete #g ,,civil ,,eng9e]+ #h ,,diction>ies #aa ,,dome/ic ,,economy #ab ,,draw+ #ac ,,electrical ,,eng9e]+ #ad ,,=eign ,,ex*ange #ai ,,gas ,,& ,,oil ,,eng9es #bj ,,gas ,,light+ #bj ,,hi/orical2 ,,biographical #ba ,,horology #bb ,,hydraulics #bb ,,indu/rial ,,*emi/ry #bd ,,irrigation #bg ,,log>i?m ,,tables #bh ,,manufactures #bd ,,m>9e ,,eng9e]+ #bh ,,mat]ials #cj ,,ma!matics #ca ,,me*anical ,,eng9e]+ #cc ,,metallurgy #cf ,,metric ,,tables #ch ,,m9]alogy ,,& ,,m9+ #ch ,,municipal ,,eng9e]+ #de ,,naval ,,ar*itecture #bh ,,organisation #dj ,,physics #da ,,price ,,books #db ,,railway ,,eng9e]+ #dc ,,sanitation #de ,,/ructural ,,design #de ,,telegraph ,,codes #dg ,,w>m+2 ,,v5tilation #dg ,,wat] ,,supply #dh ,,work%op ,,practice #di ,,useful ,,tables #eb ,,miscellane\s #ec ,full p>ticul>s po/ free on application4 ,all books are b\nd 9 clo? unless o!rwise /at$4 ,,note3 ,! ,prices 9 ?is ,catalogue apply to books sold 9 ! ,unit$ ,k+dom only4 ,,a]onautics ,! ,atmosph]e3 its *>act]i/ics & dynamics4 ,by ,f4,j4,b4 ,,cordeiro4 ,) #ce illus4 #abi pp4 m$ium #hvo4 7,new ,york1 #aiaj7 net #aj #f ,!ory & ,practice ( ,model ,a]oplan+4 ,by ,v4,e4 ,,johnson4 #fa illus4 #aej pp4 cr[n #hvo4 7#aiaj7 net #c #f ,h[ to ,build a #bj-;ft4 ,biplane ,glid]4 ,by ,a4,p4 ,,morgan4 #ca illus4 #fj pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #ad47 7,new ,york1 #aiji7 net #a #f ,flight-,velocity4 ,by ,a4 ,,samuelson4 #d plates1 #db pp4 #hvo1 sew$4 7#aijf7 net #b #j ,resi/ance ( ,air & ! ,"q ( ,fly+4 ,by ,a4 ,,samuelson4 #bc illus4 #cf pp4 #hvo1 sew$4 7#aije7 net #b #j ,,agriculture4 ,hemp4 ,a ,practical ,treatise on ! ,culture = ,se$ & ,fibre4 ,by ,s4,s4 ,,boyce4 #ac illus4 #aab pp4 cr[n #hvo4 7,new ,york1 #aijj7 net #b #j ,! ,f]tilisation ( ,tea4 ,by ,g4,a4 ,,c[ie4 ,) #ag illus4 #fh pp4 cr[n #hvo1 sew$4 7#aijh7 net #b #f ,f>m ,dra9age4 ,by ,h4,f4 ,,fr5*4 #ajj illus4 #bhd pp4 cr[n #hvo4 7,new ,york1 #aijd7 net #d #f ,talks on ,manures4 ,by ,j4 ,,h>ris4 ,new edition1 #cff pp4 cr[n #hvo4 7,new ,york1 #ahic7 net #f #f ,c(fee1 its ,culture & ,comm]ce 9 all ,c\ntries4 ,by ,c4,g4,w4 ,,lock4 #aa plates1 #bgd pp4 cr[n #hvo4 7#ahhh7 #ab #f ,sug>1 a ,h&book = ,plant]s & ,ref9]s4 ,by ! late ,j4,a4 ,r4 ,,newl&s & ,b4,e4,r4 ,,newl&s4 #bcf illus4 #hgf pp4 demy #hvo4 7,london1 #aiji7 net #a #e #j ,hops1 _! ,cultivation1 ,comm]ce & ,uses4 ,by ,p4,l4 ,,simmonds4 #adc pp4 cr[n #hvo4 7#ahgg7 #d #f ,! ,future ( ,cocoa-,plant+4 ,by ,h4 ,,hamel ,,smi?4 ,) illu/rations1 #ie pp4 cr[n #hvo1 sew$4 7#aijh7 net #a #j ,e/ate ,f5ces1 _! ,*oice1 ,con/ruction & ,co/4 ,by ,a4 ,,v]non4 ,re-issue1 #aej illus4 #dbj pp4 #hvo4 7#aiji7 net #h #f ,,ar*itecture ,,& ,,build+4 ,! ,hydropa?ic ,e/abli%m5t & its ,ba?s4 ,by ,r4,o4 ,,allsop4 #h plates1 #ajg pp4 demy #hvo4 7#ahia7 #e #j ,! ,turki% ,ba?1 its ,design & ,con/ruction4 ,by ,r4,o4 ,,allsop4 #bg illus4 #aeb pp4 demy #hvo4 7#ahij7 #f #j ,public ,abattoirs1 _! ,plann+1 ,design & ,equipm5t4 ,by ,r4,s4 ,,ayl+4 #cc plates1 #ajj pp4 demy #dto4 7#aijh7 net #h #f ,! ,build]'s ,cl]k4 ,by ,t4 ,,bales4 ,second edition1 #ib pp4 fcap4 #hvo4 7#aijd7 #a #f ,gloss>y ( ,te*nical ,t]ms us$ 9 ,ar*itecture & ! ,build+ ,trades4 ,by ,g4,j4 ,,burns4 #acf pp4 cr[n #hvo4 7#ahie7 #c #f ,*imney ,design & ,!ory4 ,by ,w4,w4 ,,*ri/ie4 ,second edition1 #ed illus4 #bjj pp4 cr[n #hvo4 7,new ,york1 #aijb7 net #ab #f ,approximate ,e/imates4 ,by ,t4,e4 ,,coleman4 ,?ird edition1 #dha pp4 oblong #cbmo1 lea!r4 7#aijg7 net #e #j ,/able ,sanitation & ,con/ruction4 ,by ,t4,e4 ,,coleman4 #ahc illus4 #bbf pp4 cr[n #hvo4 7#ahig7 net #f #j ,ar*itectural ,examples 9 ,brick1 ,/one1 ,wood & ,iron4 ,by ,w4 ,,full]ton4 ,?ird edition1 #bde plates1 #bed pp4 demy #dto4 7#aijh7 net #ae #j ,bricklay+ ,sy/em4 ,by ,f4,b4 ,,gilbre?4 ,fully illu/rat$1 #cba pp4 #hvo4 7,new ,york1 #aiji7 net #ab #f ,field ,sy/em4 ,by ,f4,b4 ,,gilbre?4 #aid pp4 #abmo lea!r4 7,new ,york1 #aijh7 net #ab #f ,! ,build+ ,trades ,pocket ,book4 ,compil$ by ,r4 ,,hall4 #abmo4 ,) int]*angeable di>y net #a #f ,ditto ditto1 9 lea!r net #b #f ,! ,cl]k ( ,works' ,vade ,mecum4 ,by ,g4,g4 ,,hosk9s4 ,sev5? edition1 #eb pp4 fcap4 #hvo4 7#aija7 #a #f ,a ,h&book ( ,=mul1 ,tables1 & ,memor&a1 = ,ar*itectural ,surveyors & o!rs engag$ 9 ,build+4 ,by ,j4,t4 ,,hur/4 ,fifte5? edition1 #eab pp4 royal #cbmo1 roan4 7#aije7 net #e #j ,quantity ,survey+1 = ! ,use ( ,surveyors1 ,ar*itects1 ,eng9e]s & ,build]s4 ,by ,j4 ,,lean+4 ,fif? edition1 #icf pp4 demy #hvo4 7#aijd7 net #a #e #j ,ob/ruction to ,light4 ,a ,graphic ,me?od ( det]m9+ ,problems ( ,anci5t ,lights4 ,by ,h4,b4 ,,moleswor?4 #i fold+ plates1 #dto4 7#aijb7 net #f #j ,suburban ,h\ses4 ,a s]ies ( practical plans4 ,by ,j4,h4 ,,pe>son4 #df plates & #ab pp4 text1 cr[n #dto4 7#aije7 net #g #f ,solid ,bitum5s1 _! ,physical & ,*emical ,prop]ties & ,*emical ,analysis4 ,by ,s4,f4 ,,peckham4 #bc illus4 #cbd pp4 #hvo4 7,new ,york1 #aiji7 net #a #a #j ,roman ,ar*itecture1 ,sculpture & ,ornam5t4 ,by ,g4,b4 ,,piranesi4 #bjj plates1 reproduc$ 9 facsimile f ! orig9al4 #b vols4 ,imp]ial folio1 9 wrapp]s4 7#aijj7 net #b #b #j ,! ,sev5 ,p]iods ( ,engli% ,ar*itecture1 def9$ & illu/rat$4 ,by ,e4 ,,%>pe4 ,?ird edition1 #bj /eel plates1 royal #hvo4 7#ahhh7 #ab #f ,our ,factories1 ,work%ops & ,w>eh\ses1 _! ,sanit>y & ,fire-,resi/+ ,arrangem5ts4 ,by ,b4,h4 ,,?waite4 #ahc illus4 #bhb pp4 cr[n #hvo4 7#ahhb7 #i #j ,elem5t>y ,pr9ciples ( ,c>p5try4 ,by ,t4 ,,tr$gold & ,j4,t4 ,,hur/4 ,elev5? edition1 #dh plates1 #eag pp4 cr[n #hvo4 7#aijd7 #ab #f ,practical ,/air ,build+ & ,h&rail+4 ,by ,w4,h4 ,,wood4 #cb plates1 #ia pp4 cr[n #dto4 7#ahid7 #aj #f ,spons' ,ar*itects' & ,build]s' ,pocket ,price-,book1 ,memor&a1 ,tables & ,prices4 ,edit$ by ,,clyde ,,"y4 ,revis$ by ,,/an=d ,m4 ,,brooks4 ,illu/rat$1 #eeb pp4 #afmo1 lea!r clo? 7size #f 94 by #c 94 by 94 ?ick74 ,issu$ annually net #c #j ,heat+ ,eng9e]s' ,quantities4 ,by ,w4,l4 ,,:ite & ,g4,m4 ,,:ite4 #d plates1 #cc pp4 folio4 7#aiaj7 net #aj #f ,,artill]y4 ,guns & ,gun ,mak+ ,mat]ial4 ,by ,g4 ,,ede4 ,cr[n #hvo4 7#ahhi7 #f #j ,treatise on ,application ( ,wire to ,con/ruction ( ,ordnance4 ,by ,j4,a4 ,,longridge4 #ahj pp4 #hvo4 7#ahhd7 #a #e #j ,! ,progress ( ,artill]y3 ,naval ,guns4 ,by ,j4,a4 ,,longridge4 #hvo1 sew$4 7#ahif7 #b #j ,! ,field ,gun ( ! ,future4 ,by ,j4,a4 ,,longridge4 #hvo1 sew$4 7#ahib7 #b #f ,,bridges1 ,,ar*es1 ,,ro(s1 ,,& ,,/ructural ,,design4 ,/ra9s 9 ,ironwork4 ,by ,,h5ry ,,adams4 ,f\r? edition1 #h plates1 #fe pp4 cr[n #hvo4 7#aijd7 #e #j ,! ,practical ,design+ ( ,/ructural ,ironwork4 ,by ,,h5ry ,,adams4 #ac plates1 #aid pp4 #hvo4 7#ahid7 #h #f ,design+ ,ironwork4 ,by ,,h5ry ,,adams4 ,second s]ies4 #hvo1 sew$4 ,"p ,i4 ,a ,/eel ,box ,gird]4 7#ahid7 net #j #i ,,ii4 ,built-up ,/eel ,/an*ions4 7#aija7 net #a #c ,,iii4 ,ci/]ns & ,tanks4 7#aijb7 net #a #j ,,iv4 ,a ,firepro( ,floor4 7#aijc7 net #a #j ,a ,practical ,treatise on ,segm5tal & ,elliptical ,oblique or ,skew ,ar*es4 ,by ,g4,j4 ,,bell4 ,second edition1 #ag plates1 #abe pp4 royal #hvo4 7#aijf7 net #a #a #j ,economics ( ,con/ruction 9 relation to ,fram$ ,/ructures4 ,by ,r4,h4 ,b[4 ,?ird ?\s&1 #af plates1 #hh pp4 #hvo4 7#ahgc7 #e #j ,!ory ( ,v\ssoir ,ar*es4 ,by ,pr(4 ,w4 ,,ca94 ,?ird edition1 #bja pp4 #ahmo1 bo>ds4 7,new ,york1 #aije7 net #b #j ,new ,=mul = ! ,loads & ,deflections ( ,solid ,beams & ,gird]s4 ,by ,w4 ,,donaldson4 ,second edition1 #hvo4 7#ahgb7 #d #f ,plate ,gird] ,railway ,bridges4 ,by ,m4 ,,fitzmaurice4 #d plates1 #ajd pp4 #hvo4 7#ahie7 #f #j ,pocket ,book ( ,calculations 9 ,/resses4 ,by ,e4,m4 ,,george4 #ff illus4 #adj pp4 royal #cbmo1 half roan4 7#ahie7 #c #f ,/ra9s on ,brac$ ,iron ,ar*es & ,ar*$ ,iron ,bridges4 ,by ,a4,s4 ,,hea=d4 #ci pp4 #hvo4 7#ahhc7 #f #j ,tables = ,ro( ,fram+4 ,by ,g4,d4 ,,inskip4 ,second edition1 #dea pp4 #hvo1 lea!r4 7,new ,york1 #aije7 net #ab #f ,/resses 9 ,gird] & ,ro( ,frames1 = bo? dead & live loads1 by simple ,multiplication1 etc4 ,by ,f4,r4 ,,johnson4 #bh plates1 #bae pp4 cr[n #hvo4 7#ahid7 #f #j ,a ,graphical ,me?od = ,sw+ ,bridges4 ,by ,b4,f4 ,,la ,,rue4 #d plates1 #ajd pp4 #ahmo1 bo>ds4 7,new ,york1 #ahib7 net #b #j ,notes on ,cyl9d] ,bridge ,pi]s & ! ,well ,sy/em ( ,f\ndations4 ,by ,j4 ,,newman4 #add pp4 #hvo4 7#ahic7 #f #j ,a ,new ,me?od ( ,graphic ,/atics appli$ 9 ! ,con/ruction ( ,wr\ght ,iron ,gird]s4 ,by ,e4 ,,ol&]4 #af plates1 small folio4 7#ahhg7 #aj #f ,ref]5ce ,book = ,/atical ,calculations4 ,by ,f4 ,,ruff4 ,) diagrams1 #adj pp4 cr[n #hvo4 7#aijf7 net #e #j ,! ,/r5g? & ,proportion ( ,rivet$ ,jo9ts4 ,by ,b4,b4 ,,/oney4 #hg pp4 #hvo4 7#ahhe7 #e #j ,! ,anatomy ( ,bridgework4 ,by ,w4,h4 ,,?orpe4 #ajc illus4 #aij pp4 cr[n #hvo4 7#aijf7 net #f #j ,,cem5t ,,& ,,concrete4 ,portl& ,cem5t3 its ,manufacture1 ,te/+ & ,use4 ,by ,d4,b4 ,,butl]4 ,second edition1 #ig illus4 #cif pp4 demy #hvo4 7#aije7 net #af #j ,!ory ( ,/eel-,concrete ,ar*es & ( ,vault$ ,/ructures4 ,by ,w4 ,,ca94 ,f\r? edition1 #bg illus4 #bab pp4 #ahmo1 bo>ds4 7,new ,york1 #aijf7 net #b #j ,cem5t ,us]s' & ,buy]s' ,guide4 ,by ,,calc>e4 #aae pp4 #cbmo1 clo?4 7#aija7 net #a #f ,diagrams = ,design+ ,re9=c$ ,concrete ,/ructures4 ,by ,g4,f4 ,,dodge4 #ca illus4 #ajd pp4 oblong folio4 7,new ,york1 #aiaj7 net #ag #j ,cem5ts1 ,mort>s1 & ,concretes2 _! ,physical prop]ties4 ,by ,m4,s4 ,,falk4 #gh illus4 #agf pp4 #hvo4 7,new ,york1 #aijd7 net #aj #f ,concrete ,con/ruction1 ,me?ods & ,co/4 ,by ,h4,p4 ,,gillette & ,c4,s4 ,,hill4 #caj illus4 #fij pp4 #hvo4 7,new ,york1 #aijh7 net #a #a #j ,eng9e]s' ,pocket-,book ( ,re9=c$ ,concrete4 ,by ,e4,l4 ,,heid5rei*4 #afd illus4 #cfd pp4 cr[n #hvo1 lea!r1 gilt edges4 7,new ,york1 #aiji7 net #ab #f ,concrete ,inspection4 ,by ,c4,s4 ,,hill4 ,illu/rat$1 #agi pp4 #abmo4 7,new ,york1 #aiji7 net #d #f ,re9=c$ ,concrete4 ,by ,e4 ,,mccullo*4 #bh illus4 #abh pp4 cr[n #hvo4 7,new ,york1 #aijh7 net #f #f ,concrete & ,re9=c$ ,concrete4 ,by ,h4,a4 ,,reid4 #gae illus4 #hhd pp4 royal #hvo4 7,new ,york1 #aijg7 net #ba #j ,!ory & ,design ( ,re9=c$ ,concrete ,ar*es4 ,by ,a4 ,,reut]dahl4 #da illus4 #abf pp4 #hvo4 7,new ,york1 #aijh7 net #h #f ,practical ,cem5t ,te/+4 ,by ,w4,p4 ,,taylor4 ,) #adb illus4 #cbi pp4 demy #hvo4 7,new ,york1 #aijf7 net #ab #f ,concrete ,bridges & ,culv]ts4 ,by ,h4,g4 ,,tyrrell4 #ff illus4 #bea pp4 cr[n #hvo1 lea!r net #ab #f ,,civil ,,eng9e]+4 ,,canals1 ,,survey+4 7,see also ,,irrigation & ,,wat] ,,supply47 ,practical ,h9ts to ,"y ,eng9e]s ,employ$ on ,indian ,railways4 ,by ,a4,w4,c4 ,,addis4 ,) #ad illus4 #aed pp4 #abmo4 7#aiaj7 net #c #f ,levell+1 ,b>ometric1 ,trigonometric & ,_s4 ,by ,i4,o4 ,,bak]4 ,second edition1 #ae illus4 #ade pp4 #ahmo1 bo>ds4 7,new ,york1 #aijc7 44 net #b #j ,notes on ,in/rum5ts be/ suit$ = ,eng9e]+ ,field ,"w 9 ,india & ! ,colonies4 ,by ,w4,g4 ,,bligh4 #fe illus4 #bah pp4 #hvo4 7#ahii7 #g #f ,! ,sextant & o!r ,reflect+ ,ma!matical ,in/rum5ts4 ,by ,f4,r4 ,,bra9>d4 #cc illus4 #abj pp4 #ahmo1 bo>ds4 7,new ,york1 #ahia7 net #b #j ,practical ,design+ ( ,reta9+ ,walls4 ,by ,pr(4 ,w4 ,,ca94 ,fif? edition1 #ad illus4 #agb pp4 #ahmo1 bo>ds4 7,new ,york1 #aijh7 net #b #j ,! ,ma9t5ance ( ,macadamis$ ,roads4 ,by ,t4 ,,codr+ton4 ,second edition1 #ahf pp4 #hvo4 7#ahib7 #g #f ,reta9+ ,walls 9 ,!ory & ,practice4 ,by ,t4,e4 ,,coleman4 #ajd illus4 #afj pp4 cr[n #hvo4 7#aiji7 net #e #j ,! ,b>ometrical ,det]m9ation ( ,heights4 ,by ,f4,j4,b4 ,,cordeiro4 ,cr[n #hvo1 limp lea!r4 7,new ,york1 #ahih7 net #d #f ,on ,curv$ ,masonry ,dams4 ,by ,w4,b4 ,,cov5try4 #hvo1 sew$4 7#ahid7 #b #j ,a ,practical ,me?od ( ,det]m9+ ! ,pr(ile ( a ,masonry ,dam4 ,by ,w4,b4 ,,cov5try4 #hvo1 sew$4 7#ahid7 #b #f ,! ,/resses on ,masonry ,dams 7oblique sections74 ,by ,w4,b4 ,,cov5try4 #hvo1 sew$4 7#ahid7 #b #j ,tables = facilitat+ ! ,calculation ( ,e>?works4 ,by ,d4 ,,cunn+ham4 #abj pp4 royal #hvo #aj #f ,h&book ( ,co/ ,data = ,contractors & ,eng9e]s4 ,by ,h4,p4 ,,gillette4 #ahed pp4 cr[n #hvo1 lea!r1 gilt edges4 7,new ,york1 #aiaj7 net #a #a #j ,rock ,excavation1 ,me?ods & ,co/4 ,by ,h4,p4 ,,gillette4 #ef illus4 #cgf pp4 cr[n #hvo4 7,new ,york1 #aijd7 net #ab #f ,high ,masonry ,dams4 ,by ,e4,s4 ,,g\ld4 ,) illus4 #hh pp4 #ahmo1 bo>ds4 7,new ,york1 #ahig7 net #b #j ,grace's ,tables = ,curves1 ) h9ts to "y eng9e]s4 #h figures1 #dc pp4 oblong #hvo4 7#aijh7 net #e #j ,grace's ,e>?work ,tables4 #cf d\ble-page tables1 #dto4 7#aijg7 net #ab #f ,railway ,tunnell+ 9 ,heavy ,gr\nd4 ,by ,c4 ,,gripp]4 #c plates1 #ff pp4 royal #hvo4 7#ahgi7 #g #f ,levell+ & its ,g5]al ,application4 ,by ,t4 ,,holl[ay4 ,second edition1 #ec illus4 #adg pp4 #hvo4 7#ahie7 #e #j ,wat]ways & ,wat] ,transport 9 diff]5t ,c\ntries4 ,by ,j4,s4 ,,jeans4 #ee illus4 #ebj pp4 #hvo4 7#ahij7 net #i #j ,table ( ,b>ometrical ,heights to #bj1jjj ,feet4 ,by ,w4,h4 ,,mackesy1 ) "s practical sugge/ions by ,sir ,guild=d ,moleswor?4 #a plate1 #bd pp4 royal #cbmo4 7#ahhb7 #c #j ,aid ,book to ,eng9e]+ ,ent]prise4 ,by ,e4 ,,ma!son4 ,?ird edition1 illu/rat$1 #iaf pp4 m$ium #hvo1 buckram4 7#ahih7 #a #d #j ,a ,treatise on ,survey+4 ,by ,r4,e4 ,,middleton & ,o4 ,,*adwick4 ,second edition1 royal #hvo4 ,"p ,i4 #aa plates1 #bif pp4 7#aijd7 #aj #f ,,ii4 ,fully illu/rat$1 #ccd pp4 7#aijf7 #aj #f ,a ,pocket ,book ( ,useful ,=mul & ,memor&a1 = ,civil & ,me*anical ,eng9e]s4 ,by ,sir ,g4,l4 ,,moleswor? & ,h4,b4 ,,moleswor?4 ,) an ,electrical ,supplem5t by ,w4,h4 ,,moleswor?4 ,tw5ty-six? edition1 #gfj illus4 #ija pp4 royal #cbmo1 ,fr5* morocco1 gilt edges4 7#aijh7 net #e #j ,! ,pocket ,books ( ,sir ,g4,l4 ,moleswor? & ,j4,t4 ,hur/1 pr9t$ on ,india pap] & b\nd 9 "o vol4 ,royal #cbmo1 russia1 gilt edges4 net #aj #f ,metallic ,/ructures3 ,corrosion & ,f\l+ & _! ,prev5tion4 ,by ,j4 ,,newman4 ,illu/rat$1 #che pp4 cr[n #hvo4 7#ahif7 #i #j ,scamp+ ,tricks & ,odd ,k occasionally practis$ ^u ,public ,works4 ,by ,j4 ,,newman4 ,new impression1 #abi pp4 cr[n #hvo4 7#aijh7 net #b #j ,e>?work ,slips & ,subsid5ces on ,public ,works4 ,by ,j4 ,,newman4 #bdj pp4 cr[n #hvo4 7#ahij7 #g #f ,co-ord9ate ,geometry z appli$ to ,l& ,survey+4 ,by ,w4 ,,pilk+ton4 #e illus4 #dd pp4 #abmo4 7#aiji7 net #a #f ,diagrams = ! ,graphic ,calculation ( ,e>?work ,quantities4 ,by ,a4,h4 ,,rob]ts4 ,t5 c>ds1 fcap4 9 clo? case net #aj #f ,pione]+4 ,by ,f4 ,,%el=d1 illu/rat$4 #hh pp4 cr[n #hvo4 7#aiji7 net #c #j ,topographical ,survey+4 ,by ,g4,j4 ,,spe*t4 ,second edition1 #b plates & #bh illus4 #baj pp4 #ahmo1 bo>ds4 7,new ,york1 #ahih7 net #b #j ,spons' ,diction>y ( ,eng9e]+1 ,civil1 ,me*anical1 ,milit>y & ,naval4 #aj1jjj illus4 #dcjj pp4 sup] royal #hvo4 7#ahgd1 ,supplem5t issu$ 9 #ahha74 ,complete ) ,supplem5t1 9 #aa divisions net #c #aj #j ,ditto ditto 9 #d vols4 net #c #c #j ,survey+ & ,levell+ ,in/rum5ts4 ,by ,w4,f4 ,,/anley4 ,?ird edition1 #cgb illus4 #efb pp4 cr[n #hvo4 7#aija7 #g #f ,surveyor's ,h&book4 ,by ,t4,u4 ,,taylor4 #aaf illus4 #caj pp4 cr[n #hvo1 lea!r1 gilt edges4 7,new ,york1 #aijh7 net #h #f ,log>i?mic ,l& ,measurem5t4 ,by ,j4 ,,wallace4 #cb pp4 royal #hvo4 7#aiaj7 net #e #j ,h9ts on ,levell+ ,op]ations4 ,by ,w4,h4 ,,wells4 ,second edition1 #hvo1 sew$4 7#ahij7 net #a #j ,! ,dra9age ( ,f5s & ,l[ ,l&s by ,gravitation & ,/eam ,p[]4 ,by ,w4,h4 ,,:eel]4 #h plates1 #age pp4 #hvo4 7#ahhh7 #ab #f ,/adia ,survey+1 ! !ory ( ,/adia ,measurem5ts4 ,by ,a4 ,,w9sl[4 ,fif? edition1 #adh pp4 #ahmo1 bo>ds4 7,new ,york1 #aijb7 net #b #j ,h&book on ,ta*eometrical ,survey+4 ,by ,c4 ,,xydis4 #ee illus4 #c plates1 #fc pp4 #hvo4 7#aiji7 net #f #j ,,diction>ies4 ,te*nological ,diction>y 9 ! ,engli%1 ,spani%1 ,g]man & ,fr5* ,languages4 ,by ,d4 ,,c>los ,,huel9 ,y ,,arssu4 ,cr[n #hvo4 ,vol4 ,i4 ,,engli%-,,spani%-,,g]man-,,fr5*4 #fji pp4 7#aijf7 net #aj #f ,vol4 ,,ii4 ,,g]man-,,engli%-,,fr5*-,,spani%4 #gbj pp4 7#aijh7 net #aj #f ,vol4 ,,iii4 ,,fr5*-,,g]man-,,spani%-,,engli%4 ,9 prep>ation4 ,vol4 ,,iv4 ,,spani%-,,fr5*-,,engli%-,,g]man4 #gej pp4 7#aiaj7 net #aj #f ,engli%-,fr5* & ,fr5*-,engli% ,diction>y ( ! ,motor-,c>1 ,cycle & ,boat4 ,by ,f4 ,,lucas4 #aga pp4 cr[n #hvo4 7#aije7 net #e #j ,spani%-,engli% ,diction>y ( ,m9+ ,t]ms4 ,by ,f4 ,,lucas4 #gh pp4 #hvo4 7#aije7 net #e #j ,engli%-,russian & ,russian-,engli% ,eng9e]+ ,diction>y4 ,by ,l4 ,,meycli>4 #ajj pp4 #afmo4 7#aiji7 net #b #f ,re$'s ,polyglot ,guide to ! ,m>9e ,eng9e1 9 ,engli%1 ,fr5*1 ,g]man & ,norsk4 ,second edition1 oblong #hvo4 7#aijj74 net #f #j ,,dome/ic ,,economy4 ,food ,adult]ation & its ,detection4 ,by ,j4,p4 ,,batt]%all4 #ab plates1 #cbh pp4 demy #hvo4 7,new ,york1 #ahhg7 #ae #j ,h[ to ,*eck ,electricity ,bills4 ,by ,s4,w4 ,,bord54 #da illus4 #ed pp4 cr[n #hvo4 7,new ,york1 #aijg7 net #b #j ,practical ,h9ts on ,tak+ a ,h\se4 ,by ,h4,p4 ,,b\lnois4 #ga pp4 #ahmo4 7#ahhe7 #a #f ,! ,cook+ ,range1 its ,fail+s & ,rem$ies4 ,by ,f4 ,,dye4 #eb pp4 fcap4 #hvo1 sew$4 7#ahhh7 #j #f ,! ,kit*5 ,boil] & ,wat] ,pipes4 ,by ,h4 ,,grim%aw4 #hvo1 sew$4 7#ahhg7 net #a #j ,cook]y & ,dome/ic ,managem5t1 includ+ economic & middle class ,practical ,cook]y4 ,by ,k4 ,,melli%4 #ef col\r$ plates & #dda illus4 #ihg pp4 sup]-royal #hvo4 7#aija7 net #af #j ,spons' ,h\sehold ,manual4 #bej illus4 #ajdc pp4 demy #hvo4 7#aijb7 #g #f ,ditto ditto half-b\nd ,fr5* morocco #i #j ,h&book ( ,sanit>y ,in=mation = ,h\sehold]s4 ,by ,r4,s4 ,,tracy4 #cc illus4 #aad pp4 #ahmo4 7,new ,york1 #aijj7 #b #f ,,draw+4 ,! ,ornam5tal ,p5man's1 ,engrav]'s & ,sign ,writ]'s ,pocket ,book ( ,alphabets4 ,by ,b4 ,,alex&]4 ,oblong #abmo1 sew$ #j #f ,! ,draughtsman's ,h&book ( ,plan & ,map ,draw+4 ,by ,g4,g4 ,,&re4 #hg illus4 & #cd pla9 & col\r$ plates1 #afb pp4 cr[n #dto4 7#ahia7 #i #j ,slide ,valve ,diagrams3 a ,fr5* ,me?od = _! ,con/ruction4 ,by ,l4 ,,bankson4 #ahmo1 bo>ds4 7,new ,york1 #ahib7 4 4 4 net #b #j ,a ,sy/em ( ,easy ,lett]+4 ,by ,j4,h4 ,,cromwell4 ,) ,supplem5t by ,g4 ,,m>t94 ,six? ?\s&1 oblong #hvo4 7,new ,york1 #aijj7 net #b #j ,plane ,geometrical ,draw+4 ,,by ,r4,c4 ,,fawdry4 ,illu/rat$1 #ahe pp4 cr[n #hvo4 7#aija7 net #c #j ,twelve ,plates on ,projection ,draw+4 ,by ,o4 ,,gue?4 ,oblong #dto4 7,new ,york1 #aijc7 net #c #j ,h9ts on ,ar*itectural ,draughtsman%ip4 ,by ,g4,w4,t4 ,,hallatt4 ,f\r? edition1 #hj pp4 #ahmo4 7#aijf7 net #a #f ,a ,fir/ ,c\rse ( ,me*anical ,draw+ 7,trac+74 ,by ,g4 ,,halliday4 ,oblong #dto1 sew$ #b #j ,draw+s = ,m$ium-siz$ ,repetition ,"w4 ,by ,r4,d4 ,,sp9ney4 ,) #dg illus4 #acj pp4 #hvo4 7#aiji7 net #c #f ,ma!matical ,draw+ ,in/rum5ts4 ,by ,w4,f4 ,,/anley4 ,sev5? edition1 #bfe illus4 #cgj pp4 cr[n #hvo4 7#aijj7 #e #j ,,electrical ,,eng9e]+4 ,practical ,electric ,bell ,fitt+4 ,by ,f4,c4 ,,allsop4 ,t5? edition1 #ahf illus4 includ+ #h fold+ plates1 #ahe pp4 cr[n #hvo4 7#aijc7 #c #f ,telephones3 _! ,con/ruction & ,fitt+4 ,by ,f4,c4 ,,allsop4 ,eigh? edition1 #ahd illus4 #bbb pp4 cr[n #hvo4 7#aiji7 #c #f ,!rmo-electric ,reactions & ,curr5ts betwe5 ,metals 9 ,fus$ ,salts4 ,by ,t4 ,,&rews4 #hvo1 sew$4 7#ahif7 #a #j ,auto-,trans=m] ,design4 ,by ,a4,h4 ,,av]y4 #be illus4 #fj pp4 #hvo4 7#aiji7 net #c #f ,pr9ciples ( ,electric ,p[] 7,cont9u\s ,curr5t7 = ,me*anical ,eng9e]s4 ,by ,a4,h4 ,,bate4 #fc illus4 #bjd pp4 cr[n #hvo4 7#aije7 7,,f9sbury ,,te*nical ,,manual7 net #d #f ,practical ,con/ruction ( ,electric ,tramways4 ,by ,,william ,r4 ,,b[k]4 #ic illus4 #aai pp4 #hvo4 7#aijc7 net #f #j ,design & ,con/ruction ( ,induction ,coils4 ,by ,a4,f4 ,,coll9s4 #aee illus4 #bgb pp4 demy #hvo4 7,new ,york1 #aiji7 net #ab #f ,swit*bo>d ,measur+ ,in/rum5ts = ,cont9u\s & ,polyphase ,curr5ts4 ,by ,j4,c4 ,,connan4 #aag illus4 #aej pp4 #hvo1 clo?4 7#aijh7 net #e #j ,electric ,cables1 _! ,con/ruction & ,co/4 ,by ,d4 ,,coyle & ,f4,j4 ,o4 ,,h[e4 ,) _m diagrams & #baf tables1 #dfg pp4 cr[n #hvo1 lea!r4 7#aiji7 net #ae #j ,managem5t ( ,electrical ,ma*9]y4 ,by ,f4,b4 ,,crock] & ,s4,s4 ,,:eel]4 ,eigh? edition1 #aca illus4 #bbc pp4 cr[n #hvo4 7,new ,york1 #aiji7 net #d #f ,electric ,light+3 ,a ,practical ,exposition ( ! ,art4 ,by ,f4,b4 ,,crock]4 ,royal #hvo4 7,new ,york47 ,vol4 ,i4 ,! ,g5]at+ ,plant4 ,six? edition1 #bac illus4 #dgj pp4 7#aijd7 net #ab #f ,vol4 ,,ii4 ,di/ribut+ ,sy/ems & ,lamps4 ,second edition1 #cia illus4 #eje pp4 7#aije7 net #ab #f ,! ,c>e & ,managem5t ( ,ignition ,accumulators4 ,by ,h4,h4,u4 ,,cross4 #ab illus4 #gd pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #ai47 7#aiaj7 net #a #f ,elem5t>y ,telegraphy & ,telephony4 ,by ,,ar?ur ,,crot*4 #bch illus4 #bbc pp4 #hvo4 7#aijc47 7,,f9sbury ,,te*nical ,,manual7 net #d #f ,electricity & ,magnetism 9 ,telephone ,ma9t5ance4 ,by ,g4,w4 ,,cumm+s4 #de illus4 #acg pp4 #hvo4 7,new ,york1 #aijh7 4 44 net #f #f ,gr\p+ ( ,electric ,cells4 ,by ,w4,f4 ,,dunton4 #d illus4 #ej pp4 fcap4 #hvo4 7#aijf7 net #a #f ,,magnets ,,& ,,electric ,,curr5ts4 ,by ,pr(4 ,j4,a4 ,,flem+4 ,second edition1 #acf illus4 #dag pp4 cr[n #hvo 7#aijb7 net #e #j ,notes on ,design ( ,small ,dynamo4 ,by ,,george ,,halliday4 ,second edition1 #h plates1 #hvo4 7#ahie7 #b #f ,practical ,alt]nat+ ,curr5ts & ,p[] ,transmission4 ,by ,n4 ,,h>rison4 #agb illus4 #cge pp4 cr[n #hvo4 7,new ,york1 #aijf7 #aj #f ,mak+ ,wireless ,outfits4 ,by ,n4 ,,h>rison4 #bg illus4 #fa pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #aa47 7,new ,york1 #aiji7 net #a #f ,wireless ,telephone ,con/ruction4 ,by ,n4 ,,h>rison4 #dc illus4 #gc pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,s]ies1 ,no4 #ab47 7,new ,york1 #aiji7 net #a #f ,! ,pho5ix ,fire ,(fice ,rules = ,electric ,light & ,electrical ,p[] ,in/allations4 ,by ,m4 ,,heaphy4 ,?irty-sev5? edition1 #hvo1 sew$4 7#aijh7 #j #f ,te/+ ,telegraph ,cables4 ,by ,colonel ,v4 ,,hoskio]4 ,?ird edition1 cr[n #hvo4 7#ahhi7 #d #f ,long ,di/ance ,electric ,p[] ,transmission4 ,by ,r4,w4 ,,hut*9son4 #acf illus4 #cde pp4 cr[n #hvo4 7,new ,york1 #aijg7 net #ab #f ,!ory & ,practice ( ,electric ,wir+4 ,by ,w4,s4 ,,ibbetson4 #aai illus4 #cff pp4 cr[n #hvo4 7#aiji7 net #e #j ,practical ,electrical ,eng9e]+ = ,elem5t>y ,/ud5ts4 ,by ,w4,s4 ,,ibbetson4 ,) #fa illus4 #aee pp4 cr[n #hvo4 7#aiaj7 net #c #j ,g5]al ,rules recomm5d$ = ,wir+ = ! ,supply ( ,electrical ,en]gy4 ,issu$ by ,,! ,,in/itution ,,( ,,electrical ,,eng9e]s4 #hvo1 sew$4 7,revis$1 ,april #aijg7 net #j #f ,=m ( ,model ,g5]al ,conditions recomm5d$ by ,,! ,,in/itution ,,( ,,electrical ,,eng9e]s = use 9 connection ) ,electrical ,contracts4 #hvo1 sew$4 7#aijf7 net #a #j ,a ,h&book ( ,electrical ,te/+4 ,by ,h4,r4 ,,kempe4 ,sev5? edition1 #bhe illus4 #gjf pp4 demy #hvo4 7#aijh7 net #ah #j ,application ( ,electricity to ,railway ,work+4 ,by ,w4,e4 ,,langdon4 #adb illus4 & #e plates1 #cdg pp4 #hvo4 7#ahig7 #aj #f ,h[ to ,become a ,compet5t ,motorman4 ,by ,v4,b4 ,,liv]more & ,j4 ,,williams4 #de illus4 #beb pp4 #abmo4 7,new ,york1 #aijc7 net #d #f ,electromagnets1 _! design & con/ruction4 ,by ,a4,n4 ,,mansfield4 #cf illus4 #aee pp4 #ahmo1 bo>ds4 7,new ,york1 #aija7 net #b #j ,telephone ,con/ruction1 ,me?ods & ,co/4 ,by ,c4 ,,may]4 ,) ,app5dices on ! co/ ( mat]ials & lab\r by ,j4,c4 ,,slippy4 #ajc illus4 #bhd pp4 cr[n #hvo4 7,new ,york1 #aijh7 net #ab #f ,induction ,coils4 ,by ,n4,h4 ,,s*neid]4 ,second edition1 #gi illus4 #bhe pp4 cr[n #hvo4 7,new ,york1 #aija7 net #d #f ,electric ,gas ,light+4 ,by ,n4,h4 ,,s*neid]4 #eg illus4 #aja pp4 #abmo4 7,s4 ,c4 ,,s]ies1 ,,no4 #h47 7,new ,york1 #aija7 net #b #j ,h[ to ,in/all ,electric ,bells1 ,annunciators & ,al>ms4 ,by ,n4,h4 ,,s*neid]4 #ei illus4 #fc pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #b47 7,new ,york1 #aije7 net #a #f ,mod]n ,prim>y ,batt]ies1 _! con/ruction1 use & ma9t5ance4 ,by ,n4,h4 ,,s*neid]4 #ed illus4 #id pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #a47 7,new ,york1 #aije7 net #a #f ,practical ,eng9e]s' ,h&book on ! ,c>e & ,managem5t ( ,electric ,p[] ,plants4 ,by ,n4,h4 ,,s*neid]4 #bjc illus4 #bgd pp4 cr[n #hvo4 7,new ,york1 #aijf7 net #e #j ,electrical ,circuits & ,diagrams1 illu/rat$ & expla9$4 ,by ,n4,h4 ,,s*neid]4 #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,nos4 #c ,,& #d47 7,new ,york7 ,"p #a4 #bag illus4 #gb pp4 7#aije7 net #a #f ,"p #b4 #gc pp4 7#aiji7 net #a #f ,electrical ,in/rum5ts & ,te/+4 ,by ,n4,h4 ,,s*neid]4 ,?ird edition4 #acc illus4 #bci pp4 cr[n #hvo4 7,new ,york1 #aijg7 net #d #f ,exp]im5t+ ) ,induction ,coils4 ,by ,n4,h4 ,,s*neid]4 #bf illus4 #gc pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #e47 7,new ,york1 #aijf7 net #a #f ,/udy ( ,electricity = ,beg9n]s4 ,by ,n4,h4 ,,s*neid]4 #ed illus4 #hh pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #f47 7,new ,york1 #aije7 net #a #f ,practical ,electrics3 a ,univ]sal ,h&ybook on ,e ,day ,electrical ,matt]s4 ,sev5? edition1 #abf illus4 #ace pp4 #hvo4 7,s4 ,c4 ,,s]ies1 ,,no4 #ac47 7,new ,york1 #aijb7 net #a #f ,! ,voltaic ,accumulator3 an elem5t>y treatise4 ,by ,e4 ,,reyni]4 ,translat$ f ! ,fr5* by ,j4,a4 ,,b]ly4 #fb illus4 #bjb pp4 #hvo #i #j ,dry ,batt]ies3 h[ to ,make & ,use !m4 ,by a ,,dry ,,batt]y ,,exp]t4 ,) additional notes by ,n4,h4 ,,s*neid]4 #cj illus4 #ei pp4 cr[n #hvo1 sew$4 7,s4 ,c4 ,,s]ies1 ,,no4 #g47 7,new ,york1 #aije7 net #a #f ,! ,diseases ( ,electrical ,ma*9]y4 ,by ,e4 ,,s*ulz4 ,edit$1 ) a ,preface1 by ,pr(4 ,s4,p4 ,,?ompson4 #db illus4 #hd pp4 cr[n #hvo net #b #j ,electric ,toy-,mak+4 ,by ,t4,o4 ,,sloane4 ,fifte5? edition1 #gj illus4 #ahc pp4 cr[n #hvo4 7,new ,york1 #aijc7 net #d #f ,electricity ,simplifi$4 ,by ,t4,o4 ,,sloane4 ,t5? edition1 #bi illus4 #aeh pp4 cr[n #hvo4 7,new ,york1 #aija7 net #d #f ,h[ to become a ,successful ,electrician4 ,by ,t4,o4 ,,sloane4 ,?ird edition1 illu/rat$1 cr[n #hvo4 7,new ,york1 #ahii7 net #d #f ,electricity3 its ,!ory1 ,s\rces & ,applications4 ,by ,j4,t4 ,,sprague4 ,?ird edition1 #aji illus4 #feh pp4 cr[n #hvo4 7#ahib7 net #g #f ,telegraphic ,connections4 ,by ,c4 ,,?om & ,w4,h4 ,,jones4 #bj plates1 #ei pp4 oblong #hvo4 7,new ,york1 #ahib7 net #c #f ,rntg5 ,rays & ,ph5om5a ( ! ,anode & ,ca?ode4 ,by ,e4,p4 ,,?ompson & ,w4,a4 ,,an?ony4 #aje illus4 #bjd pp4 #hvo4 7,new ,york1 #ahif7 net #d #f ,dynamo ,electric ,ma*9]y4 ,by ,pr(4 ,s4,p4 ,,?ompson4 ,sev5? edition1 demy #hvo4 7,,f9sbury ,,te*nical ,,manual47 ,vol4 ,i4 ,cont9u\s-,curr5t ,ma*9]y4 ,) #d col\r$ & #cj fold+ plates1 #egc illus4 #ihd pp4 7#aijd7 net #a #aj #j ,vol4 ,,ii4 ,alt]nat+ ,curr5t ,ma*9]y4 #ae col\r$ & #bd fold+ plates1 #edf illus4 #ijj pp4 7#aije7 net #a #aj #j ,design ( ,dynamos 7,cont9u\s ,curr5ts74 ,by ,pr(4 ,s4,p4 ,,?ompson4 #d col\r$ & #h fold+ plates1 #bdc pp4 demy #hvo4 7#aijc7 net #ab #j ,s*$ule = ,dynamo ,design1 issu$ ) ! above4 #f;d4 ea*1 #ds4 p] doz41 or #ahs4 p] #ajj net ,curves ( ,magnetic ,data = ,v>i\s ,mat]ials4 ,a repr9t on transp>5t pap] = (fice use ( ,plate ,l f ,dynamo ,electric ,ma*9]y1 & measur+ #be 94 by #af 94 net #j #g ,! ,electromagnet4 ,by ,c4,r4 ,,und]hill4 #fg illus4 #aei pp4 cr[n #hvo4 7,new ,york1 #aijc7 net #f #f ,practical ,guide to ! ,te/+ ( ,insulat$ ,wires & ,cables4 ,by ,h4,l4 ,,webb4 ,fif? edition1 #ch illus4 #aah pp4 cr[n #hvo4 7,new ,york1 #aijb7 net #d #f ,,=eign ,,ex*ange4 ,engli% ,prices ) ,russian ,equival5ts 7at ,f\rte5 ,rates ( ,ex*ange74 ,engli% prices p] lb41 ) equival5ts 9 r\bles & kopecks p] pood4 ,by ,a4 ,,adiassewi*4 #ahb pp4 fcap4 #cbmo1 roan4 7#aijh7 net #a #j ,engli% ,prices ) ,g]man ,equival5ts 7at ,sev5 ,rates ( ,ex*ange74 ,engli% prices p] lb41 ) equival5ts 9 m>ks p] kilogramme4 ,by ,/4 ,,koczor[ski4 #ie pp4 fcap4 #cbmo1 roan4 7#aiji7 net #a #j ,engli% ,prices ) ,spani% ,equival5ts4 ,at ,sev5 ,rates ( ,ex*ange4 ,engli% prices p] lb41 ) equival5ts 9 pesetas p] kilogramme4 ,by ,s4 ,,lamb]t4 #ie pp4 #cbmo1 roan4 7#aiaj7 net #a #j ,engli% ,prices ) ,fr5* ,equival5ts 7at ,sev5 ,rates ( ,ex*ange74 ,engli% prices p] lb4 to francs p] kilogramme4 ,by ,h4,p4 ,,mcc>tney4 #ig pp4 #cbmo1 roan4 7#aijg7 net #a #j ,pr9ciples ( ,=eign ,ex*ange4 ,by ,e4 ,,ma!son4 ,f\r? edition1 #ed pp4 #hvo1 sew$4 7#aije7 net #j #c ,,gas ,,& ,,oil ,,eng9es4 ,! ,!ory ( ! ,gas ,eng9e4 ,by ,d4 ,,cl]k4 ,edit$ by ,f4,e4 ,,idell4 ,?ird edition1 #ai illus4 #ahj pp4 #ahmo1 bo>ds4 7,new ,york1 #aijc7 net #b #j ,! ,design & ,con/ruction ( ,oil ,eng9es4 ,by ,a4,h4 ,,gold+ham4 ,?ird edition1 #aab illus4 #bfj pp4 cr[n #hvo4 7,new ,york1 #aiaj7 net #aj #f ,gas ,eng9e 9 ,pr9ciple & ,practice4 ,by ,a4,h4 ,,gold+ham4 #ajg illus4 #aie pp4 #hvo1 clo?4 7,new ,york1 #aijg7 net #f #f ,practical ,h&-,book on ! ,c>e & ,managem5t ( ,gas ,eng9es4 ,by ,g4 ,,lieckfeld4 ,?ird edition1 squ>e #afmo4 7,new ,york1 #ahif7 #c #f ,elem5ts ( ,gas ,eng9e ,design4 ,by ,s4,a4 ,,moss4 #aig pp4 #ahmo1 bo>ds4 7,new ,york1 #aijg7 net #b #j ,gas & ,petroleum ,eng9es4 ,a ,manual = ,/ud5ts & ,eng9e]s4 7,,f9sbury ,,te*nical ,,manual47 ,by ,pr(4 ,w4 ,,rob9son4 ,?ird edition 9 prep>ation ,,gas ,,light+4 ,gas ,analy/'s ,manual 7incorporat+ ,h>tley's ,gas ,analy/'s ,manual & ,gas ,measurem5t74 ,by ,j4 ,,abady4 #ajb illu/rations1 #egf pp4 demy #hvo4 7#aijb7 net #ah #j ,gas ,works3 _! ,arrangem5t1 ,con/ruction1 ,plant & ,ma*9]y4 ,by ,f4 ,,coly]4 #ca fold+ plates1 #acd pp4 #hvo4 7#ahhd7 net #h #f ,transactions ( ! ,in/itution ( ,gas ,eng9e]s4 ,edit$ by ,,walt] ,t4 ,,dunn1 ,secret>y4 ,publi%$ annually4 #hvo net #aj #f ,light+ by ,acetyl5e4 ,by ,f4 ,,dye4 #ge illus4 #bjj pp4 cr[n #hvo4 7#aijb7 net #f #j ,a ,comp>ison ( ! ,engli% & ,fr5* ,me?ods ( ,asc]ta9+ ! ,illum9at+ ,p[] ( ,coal ,gas4 ,by ,a4,j4 ,,van ,,eijndhov54 ,illu/rat$1 cr[n #hvo4 7#ahig7 #d #j ,gas ,light+ & ,gas ,fitt+4 ,by ,w4,p4 ,,g]h>d4 ,second edition1 #aij pp4 #ahmo1 bo>ds4 7,new ,york1 #ahid7 net #b #j ,a ,treatise on ! ,comp>ative ,comm]cial ,values ( ,gas ,coals & ,cannels4 ,by ,d4,a4 ,,graham4 #c plates1 #ajj pp4 #hvo4 7#ahhb7 #d #f ,! ,gas ,eng9e]'s ,laboratory ,h&book4 ,by ,j4 ,,hornby4 ,?ird edition1 revis$1 #gj illus4 #ccj pp4 cr[n #hvo4 7#aiaj7 net #f #j ,,hi/orical ,,& ,,biographical4 ,extracts f ! ,private ,lett]s ( ! late ,sir ,william ,fo!rgill ,cooke1 #ahcf-i1 relat+ to ! ,inv5tion & ,developm5t ( ! ,electric ,telegraph2 also a ,memoir by ,,latim] ,,cl>k4 ,edit$ by ,f4,h4 ,,webb4 ,sec4 ,in/4,e4,e4 #hvo4 7#ahie7 #c #j ,a ,*ronology ( ,inl& ,navigation 9 ,great ,brita94 ,by ,h4,r4 ,,de ,,salis4 ,cr[n #hvo4 7#ahig7 #d #f ,a ,hi/ory ( ,electric ,telegraphy to ! ye> #ahcg4 ,by ,j4,j4 ,,fahie4 #ce illus4 #edb pp4 cr[n #hvo4 7#ahhi7 #b #j ,hi/ory & ,developm5t ( ,/eam ,locomotion on ,common ,roads4 ,by ,w4 ,,flet*]4 #aji illus4 #bhh pp4 #hvo #e #j ,life z an ,eng9e]3 its ,lights1 ,%ades1 & ,prospects4 ,by ,j4,w4,c4 ,,haldane4 #bc plates1 #cch pp4 cr[n #hvo4 7#aije7 net #e #j ,philipp ,reis1 ,inv5tor ( ! ,telephone3 a ,biographical ,sket*4 ,by ,pr(4 ,s4,p4 ,,?ompson4 #hvo1 clo?4 7#ahhc7 #g #f ,! ,developm5t ( ! ,m]curial ,air ,pump4 ,by ,pr(4 ,s4,p4 ,,?ompson4 ,illu/rat$1 royal #hvo1 sew$4 7#ahhh7 #a #f ,,horology4 ,wat* & ,clock ,mak]'s ,h&book1 ,diction>y & ,guide4 ,by ,f4,j4 ,,britt54 ,t5? edition1 #dej illus4 #dib pp4 cr[n #hvo4 7#aijb7 net #e #j ,! ,spr++ & ,adju/+ ( ,wat*es4 ,by ,f4,j4 ,,britt54 #ge illus4 #aeb pp4 cr[n #hvo4 7#ahih7 net #c #j ,prize ,essay on ! ,balance ,spr+ & its ,iso*ronal ,adju/m5ts4 ,by ,m4 ,,immis*4 #g illus4 #ej pp4 cr[n #hvo4 7#ahgb7 #b #f ,,hydraulics ,,& ,,hydraulic ,,ma*9]y4 7,see also ,,wat] ,,supply47 ,pumps3 ,hi/orically1 ,!oretically & ,practically ,consid]$4 ,by ,p4,r4 ,,bj,,rl+4 ,second edition1 #aef illus4 #bcd pp4 cr[n #hvo4 7#ahie7 #g #f ,pump ,details4 ,by ,p4,r4 ,,bj,,rl+4 #bgh illus4 #baa pp4 cr[n #hvo4 7#ahib7 #g #f ,pumps & ,pump ,motors3 ,a ,manual = ! use ( ,hydraulic ,eng9e]s4 ,by ,p4,r4 ,,bj,,rl+4 ,two vols4 #bfa plates1 #cfi pp4 royal #dto4 7#ahie74 net #a #aj #j ,practical ,h&book on ,pump ,con/ruction4 ,by ,p4,r4 ,,bj,,rl+4 ,second edition1 #i plates1 #ij pp4 cr[n #hvo4 7#aijd7 #e #j ,wat] or ,hydraulic ,motors4 ,by ,p4,r4 ,,bj,,rl+4 #bjf illus4 #bhg pp4 cr[n #hvo4 7#aijc7 #i #j ,hydraulic ,ma*9]y1 ) an ,introduction to ,hydraulics4 ,by ,r4,g4 ,,bla9e4 ,second edition ) #cjg illus4 #dfh pp4 #hvo4 7,,f9sbury ,,te*nical ,,manual74 7#aije7 net #ad #j ,practical ,hydraulics4 ,by ,t4 ,,box4 ,fifte5? edition1 #h plates1 #hh pp4 cr[n #hvo4 7#aiji7 net #e #j ,hydraulic1 ,/eam1 & ,h& ,p[] ,lift+ & ,press+ ,ma*9]y4 ,by ,f4 ,,coly]4 ,second edition1 #hh plates1 #baa pp4 imp]ial #hvo4 7#ahib7 net #aj #f ,pumps & ,pump+ ,ma*9]y4 ,by ,f4 ,,coly]4 ,vol4 ,i4 ,second edition1 #ec plates1 #bab pp4 #hvo 7#ahib7 net #aj #f ,vol4 ,,ii4 ,second edition1 #dh plates1 #afi pp4 #hvo4 7#aijj7 net #aj #f ,con/ruction ( ,horizontal & ,v]tical ,wat]-:eels4 ,by ,w4 ,,cull54 ,second edition1 small #dto4 7#ahga7 #e #j ,donaldson's ,poncelet ,turb9e & ,wat] ,pressure ,eng9e & ,pump4 ,by ,w4 ,,donaldson4 #dto4 7#ahhc7 #e #j ,pr9ciples ( ,con/ruction & ,effici5cy ( ,wat]-:eels4 ,by ,w4 ,,donaldson4 #ac illus4 #id pp4 #hvo4 7#ahgf7 #e #j ,practical ,hydro/atics & ,hydro/atic ,=mul4 ,by ,e4,s4 ,,g\ld4 #bg illus4 #aad pp4 #ahmo1 bo>ds4 7,new ,york1 #aijc7 net #b #j ,hydraulic & o!r ,tables = purposes ( ,sew]age & ,wat] ,supply4 ,by ,t4 ,,h5nell4 ,?ird edition1 #gj pp4 cr[n #hvo4 7#aijh7 net #d #f ,hydraulic ,tables = f9d+ ! ,mean ,velocity & ,dis*>ge 9 ,op5 ,*annels4 ,by ,t4 ,,higham4 ,second edition1 #ij pp4 sup]-royal #hvo4 7#ahih7 #g #f ,tables = ,calculat+ ! ,dis*>ge ( ,wat] 9 ,pipes = ,wat] & ,p[] ,supplies4 ,index$ at side = ready ref]5ce4 ,by ,a4,e4 ,,silk4 #fc pp4 cr[n #hvo4 7#ahii7 #e #j ,simple ,hydraulic ,=mul4 ,by ,t4,w4 ,,/one4 #i plates1 #ih pp4 cr[n #hvo4 7#ahha7 #d #j ,,indu/rial ,,*emi/ry ,,& ,,manufactures4 ,p]fumes & _! ,prep>ation4 ,by ,g4,w4 ,,ask9son4 ,translat$ f ! ,?ird ,g]man ,edition by ,i4 ,,fue/4 ,?ird edition1 #cb illus4 #cab pp4 #hvo4 7,new ,york1 #aijg7 net #ab #f ,brew+ ,calculations1 ,gaug+ & ,tabulation4 ,by ,c4,h4 ,,bat]4 #cdj pp4 #fdmo1 roan1 gilt edges4 7#ahig7 net #a #f ,a ,pocket ,book = ,*emi/s1 ,*emical ,manufactur]s1 ,metallurgi/s1 ,dy]s1 ,di/ill]s1 etc4 ,by ,t4 ,,bayley4 ,sev5? edition1 #eej pp4 royal #cbmo1 roan1 gilt edges4 7#aije7 net #e #j ,practical ,receipts = ! ,manufactur]1 ! ,me*anic1 & = ,home use4 ,by ,dr4 ,h4,r4 ,,b]keley & ,w4,m4 ,,walk]4 #bej pp4 demy #hvo4 7#aijb7 net #g #f ,a ,treatise on ! ,manufacture ( ,soap & ,c&les1 ,lubricants & ,glyc]9e4 ,by ,w4,l4 ,,c>p5t] & ,h4 ,,leask4 ,second edition1 #ajd illus4 #def pp4 cr[n #hvo4 7#ahie7 #ab #f ,a ,text ,book ( ,pap] ,mak+4 ,by ,c4,f4 ,,cross & ,e4,j4 ,,bevan4 ,?ird edition1 #ig illus4 #daa pp4 cr[n #hvo4 7#aijg7 net #ab #f ,c4,b4,s4 ,/&>d ,units & ,/&>d ,pap] ,te/s4 ,by ,c4,f4 ,,cross1 ,e4,j4 ,,bevan1 ,c4 ,,beadle & ,r4,w4 ,,s9dall4 #be pp4 cr[n #dto4 7#aijc7 net #b #f ,soda ,f\nta9 ,requisites4 ,a ,practical ,receipt ,book = ,druggi/s1 ,*emi/s1 etc4 ,by ,g4,h4 ,,dubelle4 ,?ird edition1 #aeg pp4 cr[n #hvo4 7,new ,york1 #aije7 net #d #f ,! ,*emi/ry ( ,fire & ,fire ,prev5tion4 ,by ,h4 & ,h4 ,,+le4 #de illus4 #bij pp4 cr[n #hvo4 7#aijj7 #i #j ,ice-,mak+ ,ma*9es4 ,by ,m4 ,l$\x & o!rs4 ,six? edition4 #aij pp4 #ahmo1 bo>ds4 7,new ,york1 #aijf7 net #b #j ,brew+ ) ,raw ,gra94 ,by ,t4,w4 ,lovibond4 #ge pp4 cr[n #hvo4 7#ahhc7 #e #j ,sug>1 a ,h&book = ,plant]s & ,ref9]s4 ,by ! late ,j4,a4,r4 ,,newl&s & ,b4,e4,r4 ,,newl&s4 #bcf illus4 #hgf pp4 demy #hvo4 7,london1 #aiji7 net #a #e #j ,pr9ciples ( ,lea!r ,manufacture4 ,by ,pr(4 ,h4,r4 ,,proct]4 #aja illus4 #ebj pp4 m$ium #hvo4 7#aijh7 net #ah #j ,lea!r ,indu/ries ,laboratory ,h&book ( ,analytical & ,exp]im5tal me?ods4 ,by ,h4,r4 ,,proct]4 ,second edition1 #d plates1 #df illus4 #dej pp4 demy #hvo4 7#aijh7 net #ah #j ,!oretical & ,practical ,ammonia ,refrig]ation4 ,by ,i4,i4 ,,r$wood4 ,six? ?\s&1 #ae illus4 #adf pp4 squ>e #afmo4 7,new ,york1 #aiji7 net #d #f ,brew]ies & ,malt+s4 ,by ,g4 ,,scammell & ,f4 ,,coly]4 ,second edition1 #bj plates1 #agh pp4 #hvo4 7#ahhj7 net #f #j ,factory ,glazes = ,c]amic ,eng9e]s4 ,by ,h4 ,,rum-,,bell[4 ,folio4 ,s]ies ,a1 ,leadless ,sanit>y ,glazes4 7#aijh7 net #b #b #j ,text ,book ( ,physical ,*emi/ry4 ,by ,c4,l4 ,,spey]s4 #bbd pp4 demy #hvo4 7,new ,york1 #ahih7 #i #j ,spons' ,encyclopdia ( ! ,indu/rial ,arts1 ,manufactures & ,comm]cial ,products4 #aejj illus4 #bajj pp4 sup]-royal #hvo4 7#ahhb7 ,9 #b ,vols4 clo? net #b #b #j ,pigm5ts1 ,pa9ts & ,pa9t+4 ,by ,g4 ,,t]ry4 #di illus4 #cib pp4 cr[n #hvo4 7#ahic7 #g #f ,tables = ! ,quantitative ,e/imation ( ! ,sug>s4 ,by ,e4 ,,we9 & ,w4 ,,frew4 ,cr[n #hvo4 7#ahif7 #f #j ,work%op ,receipts4 ,= ! use ( ,manufactur]s1 ,me*anics & ,sci5tific ,amateurs4 ,new & ?or\ghly revis$ edition1 cr[n #hvo4 7#aiji7 ea* ea* net #c #j ,vol4 ,i4 ,,acetyl5e ,,light+ to ,,dry+4 #bbc illus4 #ecb pp4 ,vol4 ,,ii4 ,,dye+ to ,,japann+4 #bei illus4 #edj pp4 ,vol4 ,,iii4 ,,jo9t+ ,,pipes to ,,pumps4 #bef illus4 #ebh pp4 ,vol4 ,,iv4 ,,ra9wat] ,,sep>ators to ,,w9es4 #bej illus4 #ebj pp4 ,practical ,h&book on ! ,di/illation ( ,alcohol f ,f>m ,products4 ,by ,f4,b4 ,,wright4 ,second edition1 #fj illus4 #bga pp4 cr[n #hvo4 7,new ,york1 #aijg7 444 444 net #d #f ,! ,manufacture ( ,*ocolate & o!r ,cacao ,prep>ations4 ,by ,p4 ,,zipp]]4 ,second edition1 #hg illus4 #bhj pp4 royal #hvo4 7#aijb7 net #af #j ,,irrigation4 ,! ,irrigation ,works ( ,india4 ,by ,r4,b4 ,,buckley4 ,second edition1 ) col\r$ maps & plans4 #ccf pp4 #dto1 clo?4 7#aije7 net #b #b #j ,facts1 ,figures1 & ,=mul = ,irrigation ,eng9e]s4 ,by ,r4,b4 ,,buckley4 ,) illus4 #bci pp4 l>ge #hvo4 7#aijh7 net #aj #f ,irrigat$ ,india4 ,by ,hon4 ,,alfr$ ,,deak94 ,) ,map1 #cbb pp4 #hvo4 7#ahic7 #h #f ,indian ,/orage ,res]voirs1 ) ,e>!n ,dams4 ,by ,w4,l4 ,,/range4 #ad plates & #ec illus4 #cgi pp4 demy #hvo4 7#aijd7 net #a #a #j ,irrigation ,f>m+4 ,by ,l4,m4 ,,wilcox4 ,revis$ edition1 #aac illus4 #did pp4 cr[n #hvo4 7,new ,york7 net #h #f ,egyptian ,irrigation4 ,by ,sir ,w4 ,,willcocks4 ,second edition out ( ,pr9t4 ,a few copies ( ! ,fir/ ,edition 7#ahhi7 are /ill to be _h4 ,price #aes4 net4 ,! ,nile ,res]voir ,dam at ,assuan1 & ,aft]4 ,by ,sir ,w4 ,,willcocks4 ,second edition1 #ac plates1 sup]-royal #hvo4 7#aijc7 net #f #j ,! ,assuan ,res]voir & ,lake ,mo]is4 ,by ,sir ,w4 ,,willcocks4 ,) text 9 ,engli%1 ,fr5* & ,arabic4 #e plates1 #aaf pp4 sup]-royal #hvo4 7#aijd7 net #e #j ,! ,nile 9 #aijd4 ,by ,sir ,w4 ,willcocks4 #cj plates1 #bjj pp4 sup]-royal #hvo4 7#aijd7 net #i #j ,,log>i?m ,,tables4 ,aldum's ,pocket ,fold+ ,ma!matical ,tables4 ,f\r-figure log>i?ms1 & ,anti-log>i?ms1 ,natural ,s9es1 ,tang5ts1 ,cotang5ts1 ,cos9es1 ,*ords & ,radians = all angles f #a to #ij degrees4 ,on fold+ c>d4 ,net #d;d4 #bj copies1 net #fs4 ,tables ( ,sev5-figure ,log>i?ms ( ! ,natural ,numb]s f #a to #ajh1jjj4 ,by ,c4 ,,babbage4 ,/]eotype edition1 #hvo #g #f ,%ort ,log>i?mic & o!r ,tables4 ,by ,w4,c4 ,,unw94 ,f\r? edition1 small #dto #c #j ,log>i?mic ,l& ,measurem5t4 ,by ,j4 ,,wallace4 #cb pp4 royal #hvo4 7#aiaj7 net #e #j ,a4,b4,c4 ,five-figure ,log>i?ms ) ,tables1 = ,*emi/s4 ,by ,c4,j4 ,,woodw>d4 ,cr[n #hvo net #b #f ,a4,b4,c4 ,five-figure ,log>i?ms = g5]al use1 ) lat]al index = ready ref]5ce4 ,by ,c4,j4 ,,woodw>d4 ,second edition1 ) cut lat]al ,index1 #aaf pp4 #abmo1 limp lea!r net #c #j ,,m>9e ,,eng9e]+ ,,& ,,naval ,,ar*itecture4 ,m>9e ,propell]s4 ,by ,s4,w4 ,,b>naby4 ,fif? edition1 #e plates1 #ef illus4 #ahe pp4 demy #hvo4 7#aijh7 net #aj #f ,m>9e ,eng9e]'s ,record ,book3 ,eng9es4 ,by ,b4,c4 ,,b>tley4 #hvo1 roan net #e #j ,! ,eng9e]'s & ,draughtsman's ,data ,book = ,work%op & ,(fice ,use4 ,?ird edition1 cr[n #hvo1 roan #c #j ,ya*t+ ,h9ts1 ,tables & ,memor&a4 ,by ,a4,c4 ,,frankl94 ,wai/coat pocket size1 #ajc pp4 #fdmo1 roan1 gilt edges net #a #j ,/eam%ip ,coeffici5ts1 ,spe$s & ,p[]s4 ,by ,c4,f4,a4 ,,fyfe4 #ca plates1 #bhj pp4 fcap4 #hvo1 lea!r4 7#aijg7 net #aj #f ,/eam%ips & ,_! ,ma*9]y1 f fir/ to la/4 ,by ,j4,w4,c4 ,,haldane4 #abj illus4 #ecb pp4 #hvo4 7#ahic7 #ae #j ,tables = ,con/ruct+ ,%ips' ,l9es4 ,by ,a4 ,,hogg4 ,second edition1 #hvo #g #j ,subm>9e ,boats4 ,by ,g4,w4 ,,hovga>d4 #b plates1 #ih pp4 cr[n #hvo4 7#ahhg7 #e #j ,tabulat$ ,weights ( ,angle1 ,tee1 ,bulb1 ,r\nd1 ,squ>e1 & ,flat ,iron & ,/eel = ! use ( ,naval ,ar*itects1 ,%ip-build]s1 etc4 ,by ,c4,h4 ,,jordan4 ,six? edition1 #fdj pp4 royal #cbmo1 ,fr5* morocco1 gilt edges4 7#aiji7 net #g #f ,p>ticul>s ( ,dry ,docks1 ,wet ,docks1 ,:>ves1 etc4 on ! ,riv] ,?ames4 ,compil$ by ,c4,h4 ,,jordan4 ,second edition1 #g col\r$ *>ts1 #ajc pp4 oblong #hvo4 7#aijd7 net #b #f ,m>9e ,transport ( ,petroleum4 ,by ,h4 ,,little4 #ff illus4 #bfc pp4 cr[n #hvo4 7#ahij7 #aj #f ,que/ions & ,answ]s = ,m>9e ,eng9e]s1 ) a ,practical ,treatise on ,breakd[ns at ,sea4 ,by ,t4 ,,lucas4 #ab fold+ plates1 #eae pp4 gilt edges1 cr[n #hvo4 7,new ,york1 #aijb7 net #h #j ,re$'s ,exam9ation ,pap]s = ,extra ,fir/ ,class ,eng9e]s4 ,f\r? edition1 #ad plates & #ahh illus4 #eej pp4 #hvo4 7#aijb7 net #ah #j ,re$'s ,eng9e]s' ,h&book to ! ,bo>d ( ,trade ,exam9ations = c]tificates ( ,compet5cy z ,fir/ & ,second ,class ,eng9e]s4 ,n9ete5? edition1 #cg plates1 #ceh illus4 #fif pp4 #hvo net #ad #j ,re$'s ,m>9e ,boil]s4 ,second edition1 cr[n #hvo net #d #f ,re$'s ,useful ,h9ts to ,sea-go+ ,eng9e]s4 ,f\r? edition1 #h plates1 #ej illus4 #cab pp4 cr[n #hvo4 7#aijc7 net #c #f ,,mat]ials4 ,practical ,treatise on ! ,/r5g? ( ,mat]ials4 ,by ,t4 ,,box4 ,f\r? edition1 #bg plates1 #ecf pp4 #hvo4 7#aijb7 net #ab #f ,treatise on ! ,orig91 ,progress1 ,prev5tion & ,cure ( ,dry ,rot 9 ,timb]4 ,by ,t4,a4 ,,britton4 #aj plates1 #eai pp4 cr[n #hvo4 7#ahge7 #g #f ,tw5ty ,ye>s' ,practical ,exp]i5ce ( ,natural ,asphalt & ,m9]al ,bitum54 ,by ,w4,h4 ,,delano4 #cc illus4 #gc pp4 cr[n #hvo1 p>*m5t4 7#ahic7 #b #j ,/one3 h[ to get x & h[ to use x4 ,by ,major-,g54 ,c4,e4 ,,lu>d1 ,r4,e4 #hvo1 sew$4 7#ahij7 #b #j ,te/+ ( ,pipes & ,pipe-jo9ts 9 ! ,op5 ,tr5*es4 ,by ,m4,m4 ,,pat]son4 #hvo1 sew$ 7#ahgi7 #b #j ,solid ,bitum5s4 ,by ,s4,f4 ,,peckham4 #bc illus4 #cbd pp4 #hvo4 7,new ,york1 #aiji7 net #a #a #j ,lubricants1 ,oils & ,greases4 ,by ,i4,i4 ,,r$wood4 #c plates1 #hvo4 7#ahih7 net #f #f ,practical ,treatise on ,m9]al ,oils & _! ,by-,products4 ,by ,i4,i4 ,,r$wood4 #fg illus4 #ccf pp4 demy #hvo4 7#ahig7 #ae #j ,silico-,calc>e\s ,s&/ones1 or ,build+ ,/ones f ,qu>tz1 ,s& & ,lime4 ,by ,e4 ,,/(fl]4 #e plates1 #hvo1 sew$4 7#aija7 net #d #j ,proce$+s ( ! ,fif? ,congress1 ,int]national ,association = ,te/+ ,mat]ials4 ,engli% edition4 #ahi illus4 #edi pp4 demy #hvo4 7#aiaj74 ,pap] net #ae #j ,clo? net #ah #j ,,ma!matics4 ,imag9>y ,quantities4 ,by ,m4 ,,arg&4 ,translat$ by ,,pr(4 ,,h>dy4 #ahmo1 bo>ds4 7,new ,york7 net #b #j ,text ,book ( ,practical ,solid ,geometry4 ,by ,e4,h4 ,,de ,v4 ,,atk9son4 ,revis$ by ,,major ,b4,r4 ,,w>d1 ,r4,e4 ,second edition1 #ag plates1 #hvo4 7#aija7 #g #f ,quick & ,easy ,me?ods ( ,calculat+1 & ! ,!ory & ,use ( ! ,slide ,rule4 ,by ,r4,g4 ,,bla9e4 ,?ird edition1 #f illus4 #aeb pp4 #afmo1 lea!r clo?4 7#aijg7 #b #f ,symbolic ,algebra1 or ! ,algebra ( ,algebraic ,numb]s4 ,by ,w4 ,,ca94 #ahmo1 bo>ds4 7,new ,york7 net #b #j ,nautical ,a/ronomy4 ,by ,j4,h4 ,,colv94 #abg pp4 cr[n1 #hvo4 7#aija7 net #b #f ,*emical ,problems4 ,by ,j4,c4 ,,foye4 ,f\r? edition1 #ada pp4 #ahmo1 bo>ds4 7,new ,york1 #ahih7 net #b #j ,prim] ( ! ,calculus4 ,by ,e4,s4 ,,g\ld4 ,second edition1 #bd illus4 #abb pp4 #ahmo1 bo>ds4 7,new ,york1 #ahii7 net #b #j ,elem5t>y ,treatise on ! ,calculus = ,eng9e]+ ,/ud5ts4 ,by ,j4 ,,graham4 ,?ird edition1 #bgf pp4 cr[n #hvo4 7#aije74 7,,f9sbury ,,te*nical ,,manual7 #g #f ,manual ( ! ,slide ,rule4 ,by ,f4,a4 ,,halsey4 ,second edition1 #ca illus4 #hd pp4 #ahmo1 bo>ds4 7,new ,york1 #aija7 net #b #j ,re=m 9 ,*emical & ,physical ,calculations4 ,by ,c4,j4,t4 ,,hanss54 #dto4 7#ahig7 net #f #f ,algebra ,self-,taught4 ,by ,p4 ,,higgs4 ,?ird edition1 #ajd pp4 cr[n #hvo4 7#aijc7 #b #f ,galvanic ,circuit inve/igat$ ,ma!matically4 ,by ,g4,s4 ,,ohm4 ,translat$ by ,,william ,,francis4 #bfi pp4 #ahmo1 bo>ds4 7,new ,york1 #ahia7 net #b #j ,elem5t>y ,practical ,ma!matics4 ,by ,m4,t4 ,,ormsby4 #dbj pp4 demy #hvo4 7#aijj7 net #g #f ,elem5ts ( ,graphic ,/atics4 ,by ,k4 ,,von ,,ott4 ,translat$ by ,g4,s4 ,,cl>ke4 #ic illus4 #abh pp4 cr[n #hvo4 7#aija7 #e #j ,figure ( ! ,e>?4 ,by ,f4,c4 ,,rob]ts4 #ahmo1 bo>ds4 7,new ,york7 net #b #j ,ari?metic ( ,electricity4 ,by ,t4 ,o',c4 ,,sloane4 ,?irte5? edition1 cr[n #hvo4 7,new ,york1 #aija7 net #d #f ,graphic ,me?od = ,solv+ c]ta9 ,que/ions 9 ,ari?metic or ,algebra4 ,by ,g4,l4 ,,vose4 ,second edition ) #bh illus4 #fb pp4 #ahmo1 bo>ds4 7,new ,york1 #aijb7 net #b #j ,problems 9 ,electricity4 ,a ,graduat$ ,collection compris+ all bran*es ( ,electrical ,sci5ce4 ,by ,r4 ,,web]4 ,translat$ f ! ,fr5* by ,e4,a4 ,o',,keefe4 #cd illus4 #cff pp4 cr[n #hvo4 7#aijb74 net #g #f ,,me*anical ,,eng9e]+4 ,,/eam ,,eng9es ,,& ,,boil]s1 ,,etc4 ,h&book = ,me*anical ,eng9e]s4 ,by ,,hy4 ,,adams4 ,f\r? edition1 #dbf pp4 cr[n #hvo4 7#ahig7 net #d #f ,appleby's ,h&books ( ,ma*9]y4 ,_m illu/rations1 #hvo4 ,sections #b1 #c1 #d & #f ea* #c #f ,section #e #e #j ,section #a4--,prime ,mov]s4 ,out ( ,pr9t4 ,section #b4--;,hoi/+ ,ma*9]y1 ,w9d+ ,eng9es1 etc4 ,section #c4--,out ( pr9t4 ,section #d4--,ma*9e ,tools & ,accessories4 ,section #e4--;,contractors' ,plant & ,railway ,mat]ials4 ,section #f4--,m9+1 ,colonial & ,manufactur+ ,ma*9]y4 ,eng9e]s' ,sket* ,book ( ,me*anical ,movem5ts4 ,by ,t4,w4 ,,b>b]4 ,fif? edition1 #cjjj illus4 #cee pp4 #hvo4 7#aijf7 net #aj #f ,! ,repair & ,ma9t5ance ( ,ma*9]y4 ,by ,t4,w4 ,,b>b]4 #dag illus4 #dgf pp4 #hvo4 7#ahie7 #aj #f ,slide ,valve & its ,functions1 ) special ref]5ce to ,mod]n ,practice 9 ! ,unit$ ,/ates4 ,by ,j4 ,,begtrup4 #ij diagrams1 #adf pp4 m$ium #hvo4 7,new ,york1 #aijb7 net #h #j ,practical ,treatise on ,mill ,ge>+4 ,by ,t4 ,,box4 ,fif? edition1 #aa plates1 #abh pp4 cr[n #hvo4 7#ahib7 #g #f ,safety ,valves4 ,by ,r4,h4 ,,buell4 ,?ird edition1 #bj illus4 #ajj pp4 #ahmo1 bo>ds4 7,new ,york1 #ahih7 net #b #j ,ma*9e ,design4 ,by ,pr(4 ,w4,l4 ,,ca?c>t4 ,"p ,i4 ,,fa/5+s4 #abc illus4 #bia pp4 demy #hvo4 7,new ,york1 #aijc7 net #ab #f ,*imney ,design & ,!ory4 ,by ,w4,w4 ,,*ri/ie4 ,second edition1 #ed illus4 #aib pp4 cr[n #hvo4 7,new ,york1 #aijb7 net #ab #f ,furnace ,draft3 its ,production by ,me*anical ,me?ods4 ,by ,w4,w4 ,,*ri/ie4 #e illus4 #hj pp4 #ahmo1 bo>ds4 7,new ,york1 #aijf7 net #b #j ,work+ & ,managem5t ( ,/eam ,boil]s & ,eng9es4 ,by ,f4 ,,coly]4 ,second edition1 #ajh pp4 cr[n #hvo4 7#aijb7 #c #f ,! ,/ok]s' ,cate*ism4 ,by ,w4,j4 ,,connor4 #fc pp4 limp clo?4 7#aijf7 net #a #j ,treatise on ! use ( ,belt+ = ! ,transmission ( ,p[]4 ,by ,j4,h4 ,,coop]4 ,fif? edition1 #id illus4 #cii pp4 demy #hvo4 7,new ,york1 #aija7 net #ab #f ,! ,/eam ,eng9e consid]$ z a ,!rmodynamic ,ma*9e4 ,by ,j4,h4 ,,cott]ill4 ,?ird edition1 #ci diagrams1 #ddd pp4 #hvo4 7#ahif7 #ae #j ,fireman's ,guide1 a ,h&book on ! ,c>e ( ,boil]s4 ,by ,k4,p4 ,,dahl/rom4 ,n9? edition fcap4 #hvo4 7,new ,york1 #aijb7 net #a #f ,heat = ,eng9e]s4 ,by ,c4,r4 ,,d>l+4 #aaj illus4 #dcj pp4 #hvo4 7#aijh47 7,,f9sbury ,,te*nical ,,manual47 net #ab #f ,diseases ( a ,gasol5e ,automobile1 & ,h[ to ,cure ,!m4 ,by ,a4,l4 ,,dyke & ,g4,p4 ,,dorris4 #abg illus4 #bja pp4 cr[n #hvo4 7,new ,york1 #aijc7 net #f #f ,belt ,driv+4 ,by ,g4 ,,halliday4 #c fold+ plates1 #ajj pp4 #hvo4 7#ahid7 #c #f ,worm & ,spiral ,ge>+4 ,by ,f4,a4 ,,halsey4 #ac plates1 #he pp4 #ahmo1 bo>ds4 7,new ,york1 #aijc7 net #b #j ,comm]cial ,effici5cy ( ,/eam ,boil]s4 ,by ,a4 ,,hanss54 ,l>ge #hvo1 sew$4 7#ahih7 #j #f ,corliss ,eng9e4 ,by ,j4,t4 ,,h5?orn4 ,?ird edition1 #bc illus4 #ie pp4 squ>e #afmo4 7,s4 ,c4 ,,s]ies1 ,no4 #bj47 7,new ,york1 #aiaj7 net #a #f ,liquid ,fuel = ,me*anical & ,indu/rial ,purposes4 ,by ,e4,a4 ,,brayley ,,hodgetts4 #ajf illus4 #abi pp4 #hvo4 7#ahij7 #e #j ,elem5t>y ,text-,book on ,/eam ,eng9es & ,boil]s4 ,by ,j4,h4 ,,k9ealy4 ,f\r? edition1 #ajf illus4 #bei pp4 #hvo4 7,new ,york1 #aijc7 net #h #f ,c5trifugal ,fans4 ,by ,j4,h4 ,,k9ealy4 #cc illus4 #bjf pp4 fcap4 #hvo1 lea!r4 7,new ,york1 #aije7 net #ab #f ,me*anical ,draft4 ,by ,j4,h4 ,,k9ealy4 #bg orig9al tables & #ac plates1 #adb pp4 cr[n #hvo4 7,new ,york1 #aijf7 net #h #f ,! ,a4,b4,c4 ( ! ,/eam ,eng9e1 ) a description ( ! ,automatic ,gov]nor4 ,by ,j4,p4 ,,lisk4 #f plates1 #abmo4 7,s4 ,c4 ,,s]ies1 ,no4 #ag47 7,new ,york1 #aiaj7 net #a #f ,valve ,sett+ ,record ,book4 ,by ,p4,a4 ,,l[4 #hvo1 bo>ds4 #a #f ,! ,lay-out ( ,corliss ,valve ,ge>s4 ,by ,s4,a4 ,,moss4 ,second edition1 #c plates1 #ajh pp4 #ahmo1 bo>ds4 7,new ,york1 #aijf7 net #b #j ,/eam ,boil]s1 _! ,managem5t & ,work+4 ,by ,j4 ,,peattie4 ,fif? edition1 #ce illus4 #bcj pp4 cr[n #hvo4 7#aijf7 net #d #f ,treatise on ! ,ri*>ds ,/eam ,eng9e ,indicator4 ,by ,c4,t4 ,,port]4 ,six? edition1 #c plates & #gc diagrams1 #bhe pp4 #hvo4 7#aijb7 #i #j ,practical ,treatise on ! ,/eam ,eng9e4 ,by ,a4 ,,rigg4 ,second edition1 #ajc plates1 #cgh pp4 demy #dto4 7#ahid7 #a #e #j ,p[] & its ,transmission4 ,a ,practical ,h&book = ! ,factory & ,works ,manag]4 ,by ,t4,a4 ,,smi?4 #gf pp4 fcap4 #hvo4 7#aiaj7 net #b #j ,draw+s = ,m$ium ,siz$ ,repetition ,"w4 ,by ,r4,d4 ,,sp9ney4 ,) #dg illus4 #acj pp4 #hvo4 7#aiji7 net #c #f ,slide ,valve ,simply ,expla9$4 ,by ,w4,j4 ,,t5nant4 ,revis$ by ,j4,h4 ,,k9ealy4 #da illus4 #hc pp4 cr[n #hvo4 7,new ,york1 #ahii7 net #d #f ,%aft ,gov]nors4 ,by ,w4 ,,tr9ks & ,c4 ,,hoosum4 #bg illus4 #ig pp4 #ahmo1 bo>ds4 7,new ,york1 #aije7 net #b #j ,slide & ,pi/on ,valve ,ge>$ ,/eam ,eng9es4 ,by ,w4,h4 ,,uhl&4 #dg plates & #cad illus4 #aee pp4 ,two vols4 folio1 half morocco4 7#ahhb7 #a #af #j ,h[ to run ,eng9es & ,boil]s4 ,by ,e4,p4 ,,watson4 ,fif? edition1 #ca illus4 #afj pp4 cr[n #hvo4 7,new ,york1 #aijd7 #c #f ,position ,diagram ( ,cyl9d] ) ,mey] ,cut-(f4 ,by ,w4,h4 ,,weightman4 ,on c>d4 7,new ,york7 net #a #j ,practical ,me?od ( ,design+ ,slide ,valve ,ge>+4 ,by ,e4,j4 ,,wel*4 #fi diagrams1 #bhc pp4 ,cr[n #hvo4 7#ahij7 #f #j ,elem5ts ( ,me*anics4 ,by ,t4,w4 ,,wright4 ,eigh? edition1 illu/rat$1 #chb pp4 #hvo4 7,new ,york1 #aiji7 net #aj #f ,,metallurgy4 ,,iron ,,& ,,/eel ,,manufacture4 ,life ( ,railway ,axles4 ,by ,t4 ,,&rews4 #hvo1 sew$4 7#ahie7 #a #j ,microscopic ,int]nal ,flaws 9 ,/eel ,rails & ,propell] ,%afts4 ,by ,t4 ,,&rews4 #hvo1 sew$4 7#ahif7 #a #j ,microscopic ,int]nal ,flaws1 ,induc+ ,fracture 9 ,/eel4 ,by ,t4 ,,&rews4 #hvo1 sew$4 7#ahif7 #b #j ,relations betwe5 ! ,effects ( ,/resses sl[ly appli$ & ( ,/resses sudd5ly appli$ 9 ! case ( ,iron & ,/eel3 ,comp>ative ,te/s ) ,not*$ & ,pla9 ,b>s4 ,by ,p4 ,,breuil4 #bc plates & #fj illus4 #aea pp4 #hvo4 7#aijd7 net #h #j ,brassf\nd]s' ,alloys4 ,by ,j4,f4 ,,bu*anan4 ,illu/rat$1 #abi pp4 cr[n #hvo4 7#aije7 net #d #f ,f\ndry ,nom5clature4 ,! ,m\ld]'s ,pocket ,diction>y & concise guide to ,f\ndry ,practice4 ,by ,,john ,f4 ,,bu*anan4 ,illu/rat$1 #bbe pp4 cr[n #hvo4 7#aijc7 net #e #j ,am]ican ,/&>d ,specifications = ,/eel4 ,by ,a4,l4 ,,colby4 ,second edition1 revis$1 #ajc pp4 cr[n #hvo4 7,new ,york1 #aijb7 net #e #j ,galvanis$ ,iron3 its ,manufacture & ,uses4 ,by ,j4 ,,davies4 #aci pp4 #hvo4 7#ahii7 net #e #j ,managem5t ( ,/eel4 ,by ,g4 ,,ede4 ,sev5? edition1 #baf pp4 cr[n #hvo4 7#aijc7 #e #j ,galvanis+ & ,t9n+1 ) a special ,*apt] on ,t9n+ ,grey ,iron ,ca/+s4 ,by ,w4,t4 ,,fl&]s4 #hvo4 7,new ,york7 net #h #f ,cupola ,furnace4 ,a practical treatise on ! ,con/ruction & ,managem5t ( ,f\ndry ,cupolas4 ,by ,e4 ,,kirk4 ,?ird edition1 #gh illus4 #dej pp4 demy #hvo4 7,new ,york1 #aiaj7 net #ae #j ,practical ,notes on ,pipe ,f\nd+4 ,by ,j4,w4 ,,macf>lane4 #ae plates1 #adh pp4 #hvo #ab #f ,atlas ( ,designs conc]n+ ,bla/ ,furnace ,practice4 ,by ,m4,a4 ,,pavl(f4 #abg plates1 #ad 94 by #aj 94 oblong1 sew$4 7#aijb7 net #a #a #j ,album ( ,draw+s relat+ to ! ,manufacture ( ,op5 ,he>? ,/eel4 ,by ,m4,a4 ,,pavl(f4 ,"p ,i4 ,op5 ,he>? ,furnaces4 #eb plates1 #ad 94 by #aj 94 oblong folio 9 portfolio4 7#aijd7 net #ab #j ,metallography ,appli$ to ,sid]urgic ,products4 ,by ,h4 ,,savoia4 ,translat$ by ,r4,g4 ,,corbet4 ,) #id illus4 #ahj pp4 cr[n #hvo4 7#aiaj7 net #d #f ,mod]n ,f\ndry ,practice4 ,includ+ revis$ subject matt] & tables f ,,spretson',s ,ca/+ & ,f\nd+4 ,by ,j4 ,,%>p4 ,second edition1 #bgb illus4 #gei pp4 #hvo4 7#aije7 net #a #a #j ,roll ,turn+ = ,sections 9 ,/eel & ,iron4 ,by ,a4 ,,sp5c]4 ,second edition1 #gh plates1 #dto4 7#ahid7 #a #aj #j ,,metric ,,tables4 ,fr5* ,measure & ,engli% ,equival5ts4 ,by ,j4 ,,brook4 ,second edition1 #hj pp4 fcap4 #cbmo1 roan4 7#aijf7 net #a #j ,a ,diction>y ( ,metric & o!r useful ,measures4 ,by ,l4 ,,cl>k4 #aac pp4 #hvo4 7#ahia7 #f #j ,engli% ,weights1 ) _! ,equival5ts 9 kilogrammes p] c5t4 ,by ,f4,w4,a4 ,,logan4 #if pp4 fcap4 #cbmo1 roan4 7#aijf7 net #a #j ,metric ,weights ) ,engli% ,equival5ts4 ,by ,h4,p4 ,,mcc>tney4 #hd pp4 fcap4 #cbmo4 7#aijg7 net #a #j ,metric ,tables4 ,by ,sir ,g4,l4 ,,moleswor?4 ,f\r? edition1 #ie pp4 royal #cbmo4 7#aiji7 net #b #j ,tables = ,sett+ out ,curves f #bjj metres to #djjj metres by tang5tial angles4 ,by ,h4 ,,williamson4 #d illus4 #fj pp4 #ahmo4 7#aijh7 net #b #j ,,m9]alogy ,,& ,,m9+4 ,rock ,bla/+4 ,by ,g4,g4 ,,&re4 #ab plates & #ef illus4 9 text1 #bjb pp4 #hvo4 7#ahgh7 #e #j ,w9d+ ,plants = ,great ,dep?4 ,by ,h4,c4 ,,behr4 ,9 two p>ts4 #hvo1 sew$4 7#aijb7 net #b #b #j ,practical ,treatise on ,hydraulic ,m9+ 9 ,cali=nia4 ,by ,a4,j4 ,,b[ie1 ,jun4 ,t5? edition1 #gc illus4 #cac pp4 royal #hvo4 7,new ,york1 #aije7 net #a #a #j ,manual ( ,assay+ ,gold1 ,silv]1 ,copp] & ,lead ,ores4 ,by ,w4,l4 ,,br[n4 ,twelf? edition1 #acb illus4 #ehi pp4 cr[n #hvo4 7,new ,york1 #aijg7 net #aj #f ,fire ,assay+4 ,by ,e4,w4 ,,buskett4 #fi illus4 #aje pp4 cr[n #hvo4 7,new ,york1 #aijg7 net #d #f ,t93 ,describ+ ! ,*ief ,me?ods ( ,m9+1 ,dress+1 etc4 ,by ,a4,g4 ,,*>leton4 #ae plates1 #hc pp4 cr[n #hvo4 7#ahhd7 #ab #f ,gold ,m9+ & ,mill+ 9 ,we/]n ,au/ralia1 ) ,notes ^u ,telluride ,treatm5t1 ,co/s & ,m9+ ,practice 9 o!r ,fields4 ,by ,a4,g4 ,,*>leton4 #hb illus4 & num]\s plans & tables1 #fdh pp4 sup]-royal #hvo4 7#aijc7 net #a #e #j ,m9]s' ,geology & ,prospectors' ,guide4 ,by ,g4,a4 ,,cord]4 #bi plates1 #bbd pp4 cr[n #hvo4 7#aijg7 net #e #j ,bla/+ ( ,rock 9 ,m9es1 ,qu>ries1 ,tunnels1 etc4 ,by ,a4,w4 & ,z4,w4 ,,daw4 ,second edition1 #ij illus4 #caf pp4 demy #hvo4 7#aiji7 net #ae #j ,h&book ( ,m9]alogy2 det]m9ation & description ( ,m9]als f\nd 9 ! ,unit$ ,/ates4 ,by ,j4,c4 ,,foye4 #ahmo1 bo>ds4 7,new ,york1 #ahhf7 net #b #j ,conv]sations on ,m9es4 ,by ,w4 ,,hopton4 ,n9? edition1 #cc illus4 #cef pp4 cr[n #hvo4 7#ahia7 #d #f ,our ,coal ,res\rces at ! ,end ( ! ,n9ete5? ,c5tury4 ,by ,pr(4 ,e4 ,,hull4 #aeg pp4 demy #hvo4 7#ahig7 #f #j ,hydraulic ,gold ,m9]s' ,manual4 ,by ,t4,s4,g4 ,,kirkpatrick4 ,second edition1 #ab illus4 #df pp4 cr[n #hvo4 7#ahig7 #d #j ,economic ,m9+4 ,by ,c4,g4,w4 ,,lock4 #age illus4 #fhj pp4 #hvo4 7#ahie7 net #aj #f ,gold ,mill+3 ,pr9ciples & ,practice4 ,by ,c4,g4,w4 ,,lock4 #bjj illus4 #hej pp4 demy #hvo4 7#aija7 net #a #a #j ,m9+ & ,ore-,dress+ ,ma*9]y4 ,by ,c4,g4,w4 ,,lock4 #fci illus4 #dff pp4 sup]-royal #dto4 7#ahij7 #a #e #j ,m9]s' ,pocket ,book4 ,by ,c4,g4,w4 ,,lock4 ,fif? edition1 #bcc illus4 #fbd pp4 fcap4 #hvo1 roan1 gilt edges4 7#aijh7 net #aj #f ,te/s = ,ores1 ,m9]als & ,metals ( ,comm]cial ,value4 ,by ,r4,l4 ,,mcme*54 #aeb pp4 #abmo4 7,new ,york1 #aijg7 net #e #f ,practical ,h&book = ! ,work+ ,m9] & ,prospector1 & ! ,m9+ ,inve/or4 ,by ,j4,a4 ,,mill]4 #cd illus4 #bcd pp4 cr[n #hvo4 7#ahig7 #g #f ,!ory & ,practice ( ,c5trifugal ,v5tilat+ ,ma*9es4 ,by ,d4 ,,murgue4 #g illus4 #ha pp4 #hvo4 7#ahhc7 #e #j ,examples ( ,coal ,m9+ ,plant4 ,by ,j4 ,,povey-,,h>p]4 ,second edition1 #dj plates1 #bf 94 by #bj 94 7#ahie7 net #d #d #j ,examples ( ,coal ,m9+ ,plant1 ,second ,s]ies4 ,by ,j4 ,,povey-,,h>p]4 #aj plates1 #bf 94 by #bj 94 7#aijb7 net #a #ab #f ,,organisation4 ,,acc\nts1 ,,contracts ,,& ,,managem5t4 ,organisation ( ,gold ,m9+ ,bus9ess1 ) ,specim5s ( ! ,dep>tm5tal ,report ,books & ! ,acc\nt ,books4 ,by ,,nicol ,,br[n4 ,second edition1 #bbj pp4 fcap4 folio4 7#aijc7 net #a #e #j ,manual ( ,eng9e]+ ,specifications & ,contracts4 ,by ,l4,m4 ,,haupt4 ,eigh? edition1 #cch pp4 #hvo4 7,new ,york1 #aijj7 net #ab #f ,depreciation ( ,factories1 ,municipal1 & ,indu/rial ,und]tak+s1 & _! ,valuation4 ,by ,e4 ,,ma!son4 ,f\r? edition1 #bcj pp4 #hvo1 clo?4 7#aiaj7 net #aj #f ,aid ,book to ,eng9e]+ ,ent]prise4 ,by ,e4 ,,ma!son4 ,?ird edition1 #iaf pp4 #hvo1 buckram4 7#ahih7 #a #d #j ,(fice ,managem5t4 ,a h&book = ,ar*itects & ,civil ,eng9e]s4 ,by ,w4 ,,kaye ,,p>ry4 ,new impression1 #ahg pp4 m$ium #hvo4 7#aijh7 net #e #j ,comm]cial ,organisation ( ,eng9e]+ ,factories4 ,by ,h4 ,,sp5c]4 #ib illus4 #bba pp4 #hvo4 7#aijg7 net #aj #f ,,physics4 ,,col\r1 ,,heat ,,& ,,exp]im5tal ,,sci5ce4 ,! ,entropy ,diagram & its ,applications4 ,by ,m4,j4 ,,b\lv94 #ch illus4 #hb pp4 demy #hvo4 7#ahih7 #e #j ,physical ,problems & _! ,solution4 ,by ,a4 ,,b\rg\gnon4 #bbd pp4 #ahmo1 bo>ds4 7,new ,york1 #ahig7 net #b #j ,heat = ,eng9e]s4 ,by ,c4,r4 ,,d>l+4 #aaj illus4 #dcj pp4 #hvo4 7#aijh7 7,,f9sbury ,,te*nical ,,manual7 net #ab #f ,! ,col\ri/4 ,a me?od ( det]m9+ col\r h>mony4 ,by ,j4,a4,h4 ,,hatt4 #b col\r$ plates1 #hj pp4 #hvo4 7,new ,york1 #aijh7 net #f #f ,eng9e]+ ,!rmodynamics4 ,by ,c4,f4 ,,hirs*feld4 #bb illus4 #aeg pp4 #ahmo1 bo>ds4 7,new ,york1 #aijg7 net #b #j ,exp]im5tal ,sci5ce3 ,elem5t>y1 ,practical & ,exp]im5tal ,physics4 ,by ,g4,m4 ,,hopk9s4 ,tw5ty-?ird edition1 #ibj illus4 #aajj pp4 l>ge #hvo4 7,new ,york1 #aijb7 net #a #a #j ,re=m 9 ,*emical & ,physical ,calculations4 ,by ,c4,j4,t4 ,,hanss54 ,demy #dto4 7#ahig7 net #f #f ,introduction to ! ,/udy ( ,col\r ,ph5om5a4 ,by ,j4,w4 ,,lovibond4 #aj h& col\r$ plates1 #dh pp4 #hvo4 7#aije7 net #e #j ,practical ,laws & ,data on ! ,cond5sation ( ,/eam 9 ,b>e ,pipes2 to :i* is add$ a ,translation ( ,,peclet',s ,!ory & ,exp]im5ts on ! ,transmission ( ,heat ?r\gh ,insulat+ ,mat]ials4 ,by ,c4,p4 ,,pauld+4 #ahd illus4 #ajb pp4 demy #hvo4 7,new ,york1 #aijd7 net #h #f ,! ,en]gy ,*>t4 ,practical application to reciprocat+ /eam-eng9es4 ,by ,capta9 ,h4,r4 ,,sankey4 #aeg illus4 #agj pp4 #hvo4 7#aijg7 net #g #f ,,price ,,books4 ,approximate ,e/imates4 ,by ,t4,e4 ,,coleman4 ,?ird edition1 #dha pp4 oblong #cbmo1 lea!r4 7#aijg7 net #e #j ,railway ,/ores ,price ,book4 ,by ,w4,o4 ,,kemp?orne4 #ejj pp4 demy #hvo4 7#aiji7 net #aj #f ,spons' ,eng9e]s' ,price ,book4 ,a ,synopsis ( ,curr5t ,prices & ,rates = ,eng9e]+ ,mat]ials & ,products4 ,edit$ by ,t4,g4 ,,m>l[4 #fej pp4 folio4 7#aijd7 net #g #f ,spons' ,ar*itects' & ,build]s' ,pocket ,price ,book1 ,memor&a1 ,tables & ,prices4 ,edit$ by ,,clyde ,,"y4 ,revis$ by ,,/an=d ,m4 ,,brooks4 ,illu/rat$1 #eeb pp4 #afmo1 lea!r clo? 7size #f 94 by #c 94 by 94 ?ick74 ,issu$ annually net #c #j ,,railway ,,eng9e]+4 ,practical ,h9ts to ,"y ,eng9e]s ,employ$ on ,indian ,railways4 ,by ,a4,w4,c4 ,,addis4 ,) #ad illus4 #aed pp4 #abmo4 7#aiaj7 net #c #f ,railroad ,curves & ,e>?work4 ,by ,c4,f4 ,,all54 ,?ird edition1 #d plates1 #aih pp4 #abmo1 lea!r1 gilt edges4 7,new ,york1 #aijc7 net #h #f ,field & ,(fice ,tables1 specially applicable to ,railroads4 ,by ,c4,f4 ,,all54 #bic pp4 #afmo1 lea!r4 7,new ,york1 #aijc7 net #h #f ,! two above comb9$ 9 "o vol4 limp lea!r net #ab #f ,up-to-date ,air ,brake ,cate*ism4 ,by ,r4,h4 ,,blackall4 ,tw5ty-?ird edit4 #e col\r$ plates1 #if illus4 #cje pp4 cr[n #hvo4 7,new ,york1 #aijh7 net #h #f ,simple & ,automatic ,vacuum ,brakes4 ,by ,c4 ,,briggs1 ,g4,n4,r4 #aa plates1 #hvo4 7#ahib7 #d #j ,notes on ,p]man5t-way ,mat]ial1 ,plate-lay+1 & ,po9ts & ,cross+s4 ,by ,w4,h4 ,,cole4 ,fif? edition1 #cb plates1 #agf pp4 cr[n #hvo4 7#aije7 net #g #f ,/ati/ical ,tables ( ! ,work+ ( ,railways 9 v>i\s c\ntries up to ! ye> #aijd4 ,by ,j4,d4 ,,diacomidis4 ,second edition1 #hd pp4 small folio1 sew$4 7#aijf7 net #af #j ,locomotive ,breakd[ns1 ,em]g5cies & _! ,rem$ies4 ,by ,,geo4 ,l4 ,,f[l]1 ,m4,e4 & ,w4,w4 ,,wood4 ,fif? edition1 #ib illus4 #bff pp4 #abmo4 7,new ,york1 #aijh7 net #d #f ,p]man5t-,way ,diagrams4 ,by ,f4,h4 ,,fr]e4 ,m\nt$ on l95 9 clo? cov]s4 7#aijh7 net #c #j ,=mul = ,railway ,cross+s & ,swit*es4 ,by ,j4 ,,glov]4 #i illus4 #bh pp4 royal #cbmo4 7#ahif7 #b #f ,data relat+ to ,railway ,curves & ,sup] elevations1 %[n graphically4 ,by ,j4,h4 ,,hai/e4 ,on fold+ c>d = pocket use net #j #f ,sett+ out ( ,tube ,railways4 ,by ,g4,m4 ,,hald54 #i plates1 #df illus4 #fh pp4 cr[n #dto4 7#aijg7 net #aj #f ,railway ,eng9e]+1 ,me*anical & ,electrical4 ,by ,j4,w4,c4 ,,haldane1 #ada illus4 #efc pp4 #hvo4 7#ahig7 #ae #j ,tables = sett+-out ,railway ,curves4 ,by ,c4,p4 ,,hogg4 ,a s]ies ( c>ds 9 neat clo? case #d #f ,! ,con/ruction ( ! ,mod]n ,locomotive4 ,by ,g4 ,,hughes4 #cjj illus4 #bfa pp4 #hvo4 7#ahid7 #i #j ,practical ,h9ts = ,light ,railways at ,home & ,abroad4 ,by ,f4,r4 ,,johnson4 #f plates1 #ca pp4 cr[n #hvo4 7#ahif7 #b #f ,h&book on ,railway ,/ores ,managem5t4 ,by ,w4,o4 ,,kemp?orne4 #bfh pp4 demy #hvo4 7#aijg7 net #aj #f ,railway ,/ores ,price ,book4 ,by ,w4,o4 ,,kemp?orne4 #dhg pp4 demy #hvo4 7#aiji7 net #aj #f ,tables = sett+ out ,curves = ,railways1 ,roads1 ,canals1 etc4 ,by ,a4 ,,k5n$y & ,r4,w4 ,,hackwood4 #cbmo net #b #j ,railroad ,location ,surveys & ,e/imates4 ,by ,f4 ,,lavis4 #fh illus4 #bgj pp4 #hvo4 7,new ,york1 #aijf7 net #ab #f ,tables = ,comput+ ! ,cont5ts ( ,e>?work 9 ! ,cutt+s & ,embankm5ts ( ,railways4 ,by ,w4 ,,macgregor4 ,royal #hvo #f #j ,bridge & ,tunnel ,c5tres4 ,by ,j4,b4 ,,mcma/]s4 ,illu/rat$1 #ajf pp4 #ahmo1 bo>ds4 7,new ,york1 #ahic7 net #b #j ,pione]+4 ,by ,f4 ,,%el=d4 ,illu/rat$1 #hh pp4 cr[n #hvo4 7#aiji7 net #c #j ,h&book on ,railway ,survey+ = ,/ud5ts & ,junior ,eng9e]s4 ,by ,b4 ,,/ew>t4 #ee illus4 #ih pp4 cr[n #hvo4 7#aiji7 net #b #f ,spiral ,tables4 ,by ,j4,g4 ,,sullivan4 #dg pp4 #abmo1 lea!r4 7,new ,york1 #aijh7 net #f #f ,mod]n ,briti% ,locomotives4 ,by ,a4,t4 ,,taylor4 #ajj diagrams ( pr9cipal dim5sions1 #aah pp4 oblong #hvo4 7#aijg7 net #d #f ,locomotive ,slide ,valve ,sett+4 ,by ,c4,e4 ,,tully4 ,illu/rat$1 #ahmo net #a #j ,! ,wals*a]t ,locomotive ,valve ,ge>4 ,by ,w4,w4 ,,wood4 #d plates & set ( movable c>dbo>d work+ models ( ! valves1 #aic pp4 cr[n #hvo4 7,new ,york1 #aijg7 net #f #f ,! ,we/+h\se ,e4,t4 ,air-,brake ,in/ruction ,pocket ,book4 ,by ,w4,w4 ,,wood4 #dh illus4 includ+ _m col\r$ plates1 #bdb pp4 cr[n #hvo4 7,new ,york1 #aiji7 net #h #f ,,sanitation1 ,,public ,,heal? ,,& ,,municipal ,,eng9e]+4 ,sew]s & ,dra9s = ,popul\s ,di/ricts4 ,by ,j4,w4 ,,adams4 ,n9? edition1 #ha illus4 #bcf pp4 #hvo4 7,new ,york1 #aijb7 net #aj #f ,public ,abattoirs1 _! ,plann+1 ,design & ,equipm5t4 ,by ,r4,s4 ,,ayl+4 #cc plates1 #ajj pp4 demy #dto4 7#aijh7 net #h #f ,sewage ,purification4 ,by ,e4 ,,bailey-,,d5ton4 #h plates1 #dd pp4 #hvo4 7#ahif7 #e #j ,wat] ,supply & ,sew]age ( ,c\ntry ,mansions & ,e/ates4 ,by ,e4 ,,bailey-,,d5ton4 #gf pp4 cr[n #hvo4 7#aija7 net #b #f ,sew]age & ,sewage ,purification4 ,by ,m4,n4 ,,bak]4 ,second edition1 #add pp4 #ahmo1 bo>ds4 7,new ,york1 #aije7 net #b #j ,sewage ,irrigation by ,f>m]s4 ,by ,r4,w4,p4 ,,bir*4 #hvo1 sew$4 7#ahgh7 #b #f ,sanit>y ,h\se ,dra9age1 its ,pr9ciples & ,practice4 ,by ,t4,e4 ,,coleman4 #ih illus4 #bjf pp4 cr[n #hvo4 7#ahif7 #f #j ,/able ,sanitation & ,con/ruction4 ,by ,t4,e4 ,,coleman4 #ahc illus4 #bbf pp4 cr[n #hvo4 7#ahig7 #f #j ,public ,in/itutions1 _! ,eng9e]+1 ,sanit>y & o!r ,appliances4 ,by ,f4 ,,coly]4 #bca pp4 #hvo4 7#ahhi7 net #b #j ,dis*>ge ( ,pipes & ,culv]ts4 ,by ,p4,m4 ,,cro/hwaite4 ,l>ge fold+ %eet 9 case4 net #b #f ,a ,complete & ,practical ,treatise on ,plumb+ & ,sanitation3 ,hot ,wat] ,supply1 ,w>m+ & ,v5tilation1 ,/eam ,cook+1 ,gas1 ,electric ,light1 ,bells1 etc41 ) a complete ,s*$ule ( ,prices ( ,plumb]'s ,"w4 ,by ,g4,b4 ,,davis & ,f4 ,,dye4 #b vols4 #fcg illus4 & #ba fold+ plates1 #hcj pp4 #dto1 clo?4 7#ahii7 net #a #aj #j ,/&>d ,practical ,plumb+4 ,by ,p4,j4 ,,davies4 ,vol4 ,i4 ,f\r? edition1 #gfh illus4 #cee pp4 royal #hvo4 7#aije7 net #g #f ,vol4 ,,ii4 ,second edition1 #iec illus4 #hje pp4 7#aije7 net #aj #f ,vol4 ,,iii4 #cac illus4 #bjd pp4 7#aije7 net #e #j ,cons]vancy1 or ,dry ,sanitation v]sus ,wat] ,c>riage4 ,by ,j4 ,,donk94 #g plates1 #cc pp4 #hvo1 sew$4 7#aijf7 net #a #j ,sewage ,disposal ,works1 _! ,design & ,con/ruction4 ,by ,w4,c4 ,,easdale4 ,) #afj illus4 #bfd pp4 demy #hvo4 7#aiaj7 net #aj #f ,h\se ,dra9age & ,sanit>y ,plumb+4 ,by ,w4,p4 ,,g]h>d4 ,t5? edition1 #f illus4 #bca pp4 #ahmo1 bo>ds4 7,new ,york1 #aijb7 net #b #j ,eng9e]+ ,"w 9 ,t[ns & ,cities4 ,by ,e4 ,,mccullo*4 #dd illus4 #ejb pp4 cr[n #hvo4 7,new ,york1 #aijh7 net #ab #f ,! ,treatm5t ( ,septic ,sewage4 ,by ,g4,w4 ,,raft]4 #acg pp4 #ahmo1 bo>ds4 7,new ,york1 #aijd7 net #b #j ,reports & ,inve/igations on ,sew] ,air & ,sew] ,v5tilation4 ,by ,r4,h4 ,,reeves4 #hvo1 sew$4 7#ahid7 #a #j ,! ,law & ,practice ( ,pav+ ,private ,/reet ,works4 ,by ,w4 ,,sp9ks4 ,f\r? edition1 #bef pp4 #hvo4 7#aijd7 net #ab #f ,,/ructural ,,design4 7,see ,,bridges ,,& ,,ro(s47 ,,telegraph ,,codes4 ,new ,bus9ess ,code4 #cbj pp4 n>r[ #hvo4 7,size #d 94 by #g 94 & 94 ?ick1 & weight #aj oz47 7,new ,york1 #aiji7 net #a #aj #j ,m9]s' & ,smelt]s' ,code 7=m]ly issu$ z ! ,ma/] ,telegraph ,code74 #ddh pp4 #hvo1 limp lea!r1 weight #ad oz4 7,new ,york1 #ahii7 net #b #aj #j ,billionaire ,phrase ,code1 conta9+ ov] two million s5t5ces cod$ 9 s+le words4 #ef pp4 #hvo1 lea!r4 7,new ,york1 #aijh7 net #f #f ,,w>m+ ,,& ,,v5tilation4 ,hot ,wat] ,supply4 ,by ,f4 ,,dye4 ,fif? edition1 #dh illus4 #hf pp4 cr[n #hvo4 7#aijb7 net #c #j ,a ,practical ,treatise ^u ,/eam ,heat+4 ,by ,f4 ,,dye4 #abi illus4 #bdf pp4 demy #hvo4 7#aija7 net #aj #j ,practical ,treatise on ,w>m+ ,build+s by ,hot ,wat]4 ,by ,f4 ,,dye4 #aib illus4 #cai pp4 #hvo4 clo?4 7#aije7 net #h #f ,*>ts = ,l[ ,pressure ,/eam ,heat+4 ,by ,j4,h4 ,,k9ealy4 ,small folio4 7,new ,york7 #d #f ,=mul & ,tables = ,heat+4 ,by ,j4,h4 ,,k9ealy4 #ah illus4 #ec pp4 #hvo4 7,new ,york1 #ahii7 #c #f ,me*anics ( ,v5tilation4 ,by ,g4,w4 ,,raft]4 ,second edition1 #ahmo1 bo>ds4 7,new ,york1 #ahif7 net #b #j ,pr9ciples ( ,heat+4 ,by ,w4,g4 ,,sn[4 #fb illus4 #afa pp4 #hvo4 7,new ,york1 #aijg7 net #h #f ,furnace ,heat+4 ,by ,w4,g4 ,,sn[4 ,f\r? edition1 #eb illus4 #baf pp4 #hvo4 7,new ,york1 #aiji7 net #f #f ,v5tilation ( ,build+s4 ,by ,w4,g4 ,,sn[ & ,t4 ,,nolan4 #hc pp4 #ahmo1 bo>ds4 7,new ,york1 #aijf7 net #b #j ,heat+ ,eng9e]s' ,quantities4 ,by ,w4,l4 ,,:ite & ,g4,m4 ,,:ite4 #d plates1 #cc pp4 folio4 7#aiaj7 net #aj #f ,,wat] ,,supply4 7,see also ,,hydraulics47 ,potable ,wat] & ,me?ods ( ,te/+ ,impurities4 ,by ,m4,n4 ,,bak]4 #ig pp4 #ahmo1 bo>ds4 7,new ,york1 #aije7 net #b #j ,manual ( ,hydrology4 ,by ,n4 ,,be>dmore4 ,new impression1 #ah plates1 #chd pp4 #hvo4 7#aijf7 net #aj #f ,boil] ,wat]s1 ,scale1 ,corrosion & ,f\l+4 ,by ,w4,w4 ,,*ri/ie4 #gg illus4 #bce pp4 #hvo1 clo?4 7,new ,york1 #aijg7 net #ab #f ,wat] ,s(t5+ & ,purification4 ,by ,h4 ,,collet4 ,second edition1 #f illus4 #agj pp4 cr[n #hvo4 7#aijh7 net #e #j ,treatise on ,wat] ,supply1 ,dra9age & ,sanit>y ,appliances ( ,resid5ces4 ,by ,f4 ,,coly]4 #ajj pp4 cr[n #hvo4 7#ahii7 net #a #f ,report on ! ,inve/igations into ! ,purification ( ! ,ohio ,riv] ,wat] at ,l\isville1 ,k5tucky4 ,by ,g4,w4 ,,full]4 #h plates1 #dto1 clo?4 7,new ,york1 #ahih7 net #b #b #j ,purification ( ,public ,wat] ,supplies4 ,by ,j4,w4 ,,hill4 #cad pp4 #hvo4 7,new ,york1 #ahih7 #aj #f ,well ,bor+ = ,wat]1 ,br9e & ,oil4 ,by ,c4 ,,isl]4 ,new edition 9 ! ,press4 ,me?od ( ,measur+ ,liquids ,fl[+ ?r\gh ,pipes by means ( ,met]s ( ,small ,calibre4 ,by ,pr(4 ,g4 ,,lange4 #a plate1 #af pp4 #hvo1 sew$ net #j #f ,on ,artificial ,und]gr\nd ,wat]4 ,by ,g4 ,,ri*]t4 #af illus4 #cc pp4 #hvo1 sew$4 7#aijj7 net #a #f ,notes on ,wat] ,supply 9 new ,c\ntries4 ,by ,f4,w4 ,,/one4 #ah plates1 #db pp4 cr[n #hvo4 7#ahhh7 #e #j ,! ,pr9ciples ( ,wat]works ,eng9e]+4 ,by ,j4,h4,t4 ,,tudsb]y & ,a4,w4 ,,brightmore4 ,?ird edition1 #ac fold+ plates1 #acj illus4 #ddg pp4 demy #hvo4 7#aije7 net #a #a #j ,,work%op ,,practice4 ,a ,h&book = ,appr5tic$ ,ma*9i/s4 ,by ,o4,j4 ,,beale4 ,second edition1 #hi illus41 #ada pp4 #afmo4 7,new ,york1 #aija7 net #b #f ,bicycle ,repair+4 ,by ,s4,d4,v4 ,,burr4 ,six? edition1 #bjj illus4 #bjh pp4 #hvo4 7,new ,york1 #aijc7 net #d #f ,practice ( ,h& ,turn+4 ,by ,f4 ,,camp94 ,?ird edition1 #ii illus4 #cjg pp4 cr[n #hvo4 7#ahhc7 #c #f ,calculation ( ,*ange ,:eels = ,screw ,cutt+ on ,la!s4 ,by ,d4 ,,de ,,vries4 #df illus4 #hc pp4 #hvo4 7#aijh7 net #c #j ,mill+ ,ma*9es & ,mill+ ,practice4 ,by ,d4 ,,de ,,vries4 ,) #ecf illus4 #dfd pp4 m$ium #hvo4 7#aiaj7 net #ad #j ,fr5*-,poli%]s' ,manual4 ,by a ,fr5*-,poli%]4 #ca pp4 royal #cbmo1 sew$4 7#aijb7 net #j #f ,art ( ,copp] ,smi?+4 ,by ,j4 ,,full]4 ,?ird edition1 #dge illus4 #cbe pp4 royal #hvo4 7,new ,york1 #aija7 net #ab #f ,saw ,fil+ & ,managem5t ( ,saws4 ,by ,r4 ,,grim%aw4 ,new edition1 #ha illus4 #afmo4 7,new ,york1 #aijf7 net #c #f ,pa9t & ,col\r ,mix+4 ,by ,a4,s4 ,,j5n+s4 ,f\r? edition4 #ad col\r$ plates1 #aij pp4 #hvo4 7#aiaj7 net #e #j ,! ,me*anician3 a ,treatise on ! ,con/ruction & ,manipulation ( ,tools4 ,by ,c4 ,,knight4 ,fif? edition1 #if plates1 #cig pp4 #dto4 7#ahig7 #ah #j ,turn]'s & ,fitt]'s ,pocket ,book4 ,by ,j4 ,,la ,,nicca4 #ahmo1 sew$ #j #f ,tables = ,eng9e]s & ,me*anics1 giv+ ! values ( ! diff]5t tra9s ( :eels requir$ to produce ,screws ( any pit*4 ,by ,,"l ,,l9dsay4 ,second edition1 royal #hvo1 oblong #b #j ,screw-cutt+ ,tables4 ,by ,w4,a4 ,,m>t94 ,sev5? edition1 royal #hvo1 oblong #a #j ,metal ,plate ,"w1 its ,patt]ns & _! ,geometry1 = ! use ( ,t91 ,iron & ,z9c ,plate ,work]s4 ,by ,c4,t4 ,,millis4 ,f\r? edition1 #bhj diagrams1 #dgj pp4 cr[n #hvo4 7#aijf7 #i #j ,eng9e]s' & ,g5]al ,smi?s' ,"w4 ,! smi? & =geman's h&book ( practical smi?+ & =g+4 ,by ,t4 ,,moore4 #dja illus4 #bdh pp4 cr[n #hvo4 7#aijf7 net #e #j ,mod]n ,ma*9e ,%op ,con/ruction1 equipm5t & managem5t4 ,by ,o4,e4 ,,p]rigo4 #bjh illus4 #cdc pp4 cr[n #dto4 7,new ,york1 #aijf7 net #ba #j ,turn]'s ,h&book on ,screw-cutt+1 ,con+1 etc4 ,by ,w4 ,,price4 ,fcap4 #hvo #a #j ,introduction to ,ecc5tric ,spiral ,turn+4 ,by ,h4,c4 ,,rob9son4 #ab plates1 #bc illus4 #dh pp4 #hvo4 7#aijf7 net #d #f ,manual ( ,in/ruction 9 ,h>d ,sold]+4 ,by ,h4 ,,r[ell4 ,six? edition1 #g illus4 #ff pp4 cr[n #hvo4 7,new ,york1 #aiaj7 net #c #j ,pocket ,book on ,boil]mak+1 ,%ipbuild+1 & ! ,/eel & ,iron ,trades 9 ,g5]al4 ,by ,m4,j4 ,,sexton4 ,six? edition1 #he illus4 #cai pp4 royal #cbmo1 roan1 gilt edges4 7#aiji7 net #e #j ,p[] & its ,transmission4 ,a ,practical ,h&book = ! ,factory & ,works ,manag]4 ,by ,t4,a4 ,,smi?4 #gf pp4 fcap4 #hvo4 7#aiaj7 net #b #j ,spons' ,me*anics' ,own ,book3 ,a ,manual = ,h&icraftsm5 & ,amateurs4 ,six? edition1 #adcj illus4 #gbj pp4 demy #hvo4 7#aijc7 #f #j ,ditto ditto half morocco #g #f ,spons' ,work%op ,receipts = ,manufactur]s1 ,me*anics & ,sci5tific ,amateurs4 ,new & ?or\ghly revis$ edition1 cr[n #hvo4 7#aiji7 ea* net #c #j ,vol4 ,i4 ,,acetyl5e ,,light+ to ,,dry+4 #bbc illus4 #ecb pp4 ,vol4 ,,ii4 ,,dye+ to ,,japann+4 #bei illus4 #edj pp4 ,vol4 ,,iii4 ,,jo9t+ ,,pipes to ,,pumps4 #bef illus4 #ebh pp4 ,vol4 ,,iv4 ,,ra9wat] ,,sep>ators to ,,w9es4 #bej illus4 #ebj pp4 ,gauges at a ,glance4 ,by ,t4 ,,taylor4 ,second edition1 po/ #hvo1 oblong1 ) tape conv]t]4 7#aijj7 net #e #j ,simple ,sold]+1 bo? ,h>d & ,s(t4 ,by ,e4 ,,?at*]4 #eb illus4 #gf pp4 cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,,no4 #ah47 7,new ,york1 #aiaj7 net #a #f ,! ,mod]n ,ma*9i/4 ,by ,j4,t4 ,,u%]4 ,fif? edition4 #beg illus4 #cbb pp4 #hvo4 7,new ,york1 #aijd7 net #aj #f ,practical ,wood ,c>v+4 ,by ,c4,j4 ,,woods5d4 #ajh illus4 #hf pp4 #hvo4 7,new ,york1 #ahig7 net #d #f ,am]ican ,tool ,mak+ & ,int]*angeable ,manufactur+4 ,by ,j4,w4 ,,woodwor?4 #fjj illus4 #edd pp4 demy #hvo4 7,new ,york1 #aije7 net #ag #j ,,useful ,,tables4 ,weights & ,measurem5ts ( ,%eet ,lead4 ,by ,j4 ,,alex&]4 #cbmo1 roan net #a #f ,tables ( ,p>abolic ,curves = ! use ( ,railway ,eng9e]s & o!rs4 ,by ,g4,t4 ,,all54 ,fcap4 #afmo #d #j ,b>l['s ,tables ( ,squ>es1 ,cubes1 ,squ>e ,roots1 ,cube ,roots & ,reciprocals4 ,cr[n #hvo #f #j ,tables ( ,squ>es4 ,by ,e4,e4 ,,bu*anan4 ,n9? edition1 #abmo net #d #f ,l& ,area ,tables4 ,by ,w4 ,,codd4 ,squ>e #afmo1 on a %eet m\nt$ on l95 & b\nd 9 clo? #c #f ,tables = ,sett+ out ,curves f #aja to #ejjj feet radius4 ,by ,h4,a4 ,,cutl] & ,f4,j4 ,,edge4 ,royal #cbmo net #b #f ,transition ,curves4 ,by ,w4,g4 ,,fox4 #ahmo1 bo>ds4 7,new ,york7 net #b #j ,tables ( "s ( ! ,pr9cipal ,spe$s occurr+ 9 ,me*anical ,eng9e]+1 express$ 9 ,metres p] second4 ,by ,p4 ,,ke]ayeff4 #ahmo1 sew$ #j #f ,calculat+ ,scale4 ,a ,sub/itute = ! ,slide ,rule4 ,by ,w4 ,,kn[les4 ,cr[n #hvo1 lea!r net #a #j ,planimet] ,areas4 ,multipli]s = v>i\s scales4 ,by ,h4,b4 ,,moleswor?4 ,fold+ %eet 9 clo? case4 net #a #j ,tables ( ,seamless ,copp] ,tubes4 ,by ,i4 ,o',,toole4 #fi pp4 oblong fcap4 #hvo4 7#aijh7 net #c #f ,r[nson's ,iron ,m]*ants' ,tables & ,memor&a1 ,weights & ,measures4 #hf pp4 #cbmo1 lea!r #c #f ,spons' ,tables & ,memor&a = ,eng9e]s4 ,by ,j4,t4 ,,hur/1 ,c4,e4 ,twelf? edition1 #bgh pp4 #fdmo1 roan1 gilt edges4 7#aijg7 net #a #j ,ditto ditto 9 celluloid case net #a #f ,optical ,tables & ,data1 = ! use ( ,opticians4 ,by ,pr(4 ,s4,p4 ,,?ompson4 ,second edition1 #acj pp4 oblong #hvo4 7#aijg7 net #f #j ,trav]se ,table1 %[+ ,latitudes & ,dep>ture = ea* ,qu>t] degree ( ! ,quadrant1 & = di/ances f #a to #ajj1 etc42 #ahmo1 bo>ds4 net #b #j ,fifty-f\r ,h\rs' ,wages ,calculator4 ,by ,h4,n4 ,,:itelaw4 ,second edition1 #hvo4 net #b #f ,:eel ,ge>+4 ,tables ( ,pit* ,l9e ,diamet]s1 etc4 ,by ,a4 ,,wildgoose & ,a4,j4 ,,orr4 #age pp4 fcap4 #cbmo4 7#aijc7 net #b #j ,,miscellane\s4 ,"t ,*>t4 ,! "t ( day at any place 9 ! ,_w at a glance4 ,by ,dr4 ,f4,j4,b4 ,,cordeiro4 ,on c>d4 net #a #j ,! ,atmosph]e3 ,its ,*>act]i/ics & ,dynamics4 ,by ,f4,j4,b4 ,,cordeiro4 ,) #ce illus4 #abi pp4 m$ium #hvo4 7,new ,york1 #aiaj7 net #aj #f ,model ,/eam ,eng9e ,design4 ,by ,r4,m4 ,,de ,,vigni]4 #cd illus4 #id pp4 cr[n #hvo1 limp4 7,new ,york1 #aijg7 net #a #f ,popul> ,eng9e]+4 ,by ,f4 ,,dye4 #gjd illus4 #dgg pp4 cr[n #dto4 7#ahie7 net #e #j ,! ,phonograph1 & h[ to con/ruct x4 ,by ,w4 ,,gillett4 #f fold+ plates1 #hg pp4 cr[n #hvo4 7#ahib7 #e #j ,p>ticul>s ( ,dry ,docks1 ,wet ,docks1 ,:>ves1 etc4 on ! ,riv] ,?ames4 ,by ,c4,n4 ,,jordan4 ,second edition1 #g col\r$ *>ts1 #ajc pp4 oblong #hvo4 7#aijd7 net #b #f ,spons' ,eng9e]'s ,di>y & ,ye> ,book1 issu$ annually4 #dto4 #c #f ,new ,!ories 9 ,a/ronomy4 ,by ,w4 ,,/irl+4 #cce pp4 demy #hvo4 7#aijf7 net #h #f ,! ,am]ican ,h>dw>e ,/ore4 ,a ,manual ( approv$ me?ods ( arrang+ & display+ h>dw>e4 ,by ,r4,r4 ,,williams4 #ejj illus4 #ddh pp4 royal #hvo4 7,new ,york1 #ahif7 net #g #f ,practical ,wood ,c>v+4 ,by ,c4,j4 ,,woods5d4 #ajh illus4 #hf pp4 #hvo4 7,new ,york1 #ahig7 net #d #f ,inv5tions1 ,h[ to ,protect1 ,sell & ,buy ,!m4 ,by ,f4 ,,wright4 ,cr[n #hvo1 limp4 7,s4 ,c4 ,,s]ies1 ,no4 #aj47 7,new ,york1 #aijh7 net #a #f ,illu/ration ,,sci5ce ,,ab/racts ,,section ,a4--,,physics4 ,,section ,b4--,,eng9e]+4 ,,issu$ ,,mon?ly ,,by ,,! ,,in/itution ,,( ,,electrical ,,eng9e]s1 ,,) ,,! ,,co-,,op]ation ,,( ,! ,physical ,society ( ,london1 ,! ,am]ican ,physical ,society1 ,! ,am]ican ,in/itute ( ,electrical ,eng9e]s1 & ,! ,am]ican ,electro-,*emical ,society4 ,section ,a4--,,physics4 ,annual ,subscription1 #ahs4 net1 po/-free4 ,,cont5ts3--,g5]al ,physics--,light--,heat--,electricity & ,magnetism--,*emical ,physics & ,electro-,*emi/ry4 ,dur+ #aijh & #aiji ov] #dbjj ,ab/racts & ,ref]5ces 7 includ$ "u ! above head+s4 ,section ,b4--,,electrical ,,eng9e]+4 ,annual ,subscription1 #ahs4 net1 po/-free4 ,,cont5ts3--,/eam ,plant1 ,gas & ,oil ,eng9es--,indu/rial ,electro-,*emi/ry1 ,g5]al ,electrical ,eng9e]+1 & ,prop]ties & ,treatm5t ( ,mat]ials--,g5]ators1 ,motors & ,trans=m]s--,electrical ,di/ribution1 ,traction & ,light+--,telegraphy & ,telephony4 ,dur+ #aijh & #aiji ov] #bhjj ,ab/racts & ,ref]5ces 7 includ$ "u ! above head+s4 ,annual ,subscription = ,bo? ,sections1 #cjs4 net1 po/-free4 ,b9d+ ,cases = all ,vols4 are to be _h1 price #as4 ea* 7po/-free #as4 #b;d474 ,e4 ,f4,n4 ,,spon1 ,ltd41 #eg ,haym>ket1 ,london1 ,s4,w4 ,! ,j\rnal ( ! ,iron & ,/eel ,in/itute4 ,edit$ by ,g4,c4 ,,lloyd1 ,secret>y4 ,publi%$ ,half-ye>ly1 #hvo1 clo?1 #afs4 net4 ,! ,j\rnal ( ! ,in/itution ( ,electrical ,eng9e]s4 ,edit$ by ,p4,f4 ,,r[ell1 ,secret>y4 ,! ,proce$+s ( ! ,in/itution ( ,municipal & ,c\nty ,eng9e]s4 ,edit$ by ,,?omas ,,cole1 ,assoc4 ,m4 ,in/4 ,c4,e4 ,secret>y4 ,publi%$ ,annually1 #hvo1 clo?1 #bas4 net4 ,! ,transactions ( ! ,in/itution ( ,m9+ & ,metallurgy4 ,edit$ by ,c4 ,,mcd]mid1 ,secret>y4 ,publi%$ ,annually1 bo>ds1 #bas4 net1 or half-b\nd1 #bes4 net4 ,transactions ( ! ,in/itution ( ,gas ,eng9e]s4 ,edit$ by ,,walt] ,t4 ,,dunn1 ,secret>y4 ,publi%$ ,annually1 #hvo1 clo?1 #ajs4 #f;d4 net4 ,proce$+s ( ! ,int]national ,association = ,te/+ ,mat]ials4 7,engli% ,edition47 ,e4 ,f4,n4 ,,spon1 ,ltd41 #eg ,haym>ket1 ,london1 ,s4,w4 ,,london3 ,,pr9t$ ,,by ,,william ,,cl[es ,,& ,,sons1 ,,limit$4 ,,j ,,out ,,! ,,late/ ,! ,a]oplane ,portfolio ,by ,d4 ,,ross ,,k5n$y ,conta9+ n9e %eets ( scale draw+s ( ! foll[+ celebrat$ ,a]oplanes4 ,biplane type2--,wright1 ,f>man1 ,vois91 ,cody1 ,h]r+-,curtis4 ,monoplanes2--,rep1 ,anto9ette1 ,santos ,dumont1 & ,blriot4 ,ea* ( ^! ma*9es are "h %[n 9 ,end ,view1 ,plan & ,elevation4 ,includ+ booklet :i* conta9s a description ( ea* ma*9e4 ,?is timely set ( draw+s %\ld prove ( value to ev]yone int]e/$ 9 ?is important new indu/ry4 ,! complete set mail$ to any "p ( ! _w po/paid on receipt ( net #ee;c4 ,,spon ,,*amb]la9 ,,publi%]s ,,( ,,te*nical ,,books #abc-e ,lib]ty ,/reet1--,new ,york ,illu/ration ,! ,p]cy ,pi]ce ,fly] ,a ,,fam\s ,,prize ,,w9n] ,a ,l>ge ,scale ,draw+ ( ?is fam\s model1 ) all measurem5ts & details %[+ a front elevation1 a side elevation & a top plan1 ) full descriptive matt]4 ,anybody c make an ,,exact ,,duplicate ( ?is ,prize ,w9n] = himself at small co/4 ,,d ,,x ,,n[ ,complete set ( mat]ials 9 ! r\gh ) draw+ & in/ructions1 ,po/paid1 #a4ae ,! draw+ & in/ructions #ae;c po/paid ,make ,y\r ,own ,,glid] ,h[ to make a #bj ft4 ,biplane ,glid+ ,ma*9e ,t w c>ry an ord9>y man ,practica,i h&book on ! con/ruction ( a ,biplane ,glid+ ,ma*9e enabl+ an intellig5t read] to make 8 fir/ /ep 9 ! field ( aviation ) a compreh5sive und]/&+ ( "s ( ! pr9cipals involv$4 ,by ,alfr$ ,p[ell ,morgan4 ,cont5ts ( ,*apt]s3 #a4 ,! ,framework1 ,assembl+ & f9i%+ ! wood4 #b4 ,cov]+ ! planes1 ,lay+ out ! fabric & fa/5+ x4 #c4 ,truss+1 ,fa/5+ ! tie rods & true+ ! glid]4 #d4 ,glid+ flight4 ,! pr9cipals involv$4 ,in/ructions & precautions4 #e4 ,rem>ks4 ,fully illu/rat$ ) detail draw+s4 ,by ,mail4 ,9 pap]1 po/paid1 #be;c4 ,9 h&some clo? b9d+1 po/paid1 #ee;c4 ,fly+ ,ma*9es1 ,pa/1 ,pres5t & ,future4 ,a popul> acc\nt ( fly+ ma*9es1 dirigible balloons & a]oplanes4 ,describ+ _m diff]5t k9ds ( ma*9es1 & _! *ief feature4 ,by ,a4,w4 ,m>%all & ,h5ry ,gre5ly4 #ach pages #bc illu/rations & _m plates1 #ab mo4 bo>ds4 ,by mail #ee;c4 ,model ,fly+ ,ma*9es4 ,_! design & con/ruction by ,w4,g4 ,a/on4 ,a fir/ rate little book %[+ num]\s me?ods ( propell+ models1 mak+ propellors1 con/ruction ( diff]5t k9ds ( models1 etc41 etc4 #acj pages1 #id illu/rations4 #ab mo4 bo>ds1 by mail #ee;c4 ,model ,a]oplanes4 ,h[ to ,build & ,fly ,!m1 by ,e4,w4 ,tw9+4 ,a set ( #e full-size scale draw+s = ?ree diff]5t models ) descriptive illu/rat$ book expla9+ h[ to make & fly !m4 ,po/paid 3 3 3 3 #ee;c ,no4 #b ,model4 ,complete set ( p>ts 9 ! r\gh to make up ?is model4 7,)\t draw+s71 ,po/paid 3 3 #fe;c ,illu/ration3 ,no4 #c ,model ,no4 #c ,model4 ,complete set ( p>ts 9 ! r\gh 7)\t draw+s74 ,?is makes up into a beautiful little model4 ,po/paid 3 3 3 3 #a4ae ,model ,glid]s1 ,birds1 ,butt]flies & ,a]oplanes4 ,h[ to make & fly !m1 by ,e4,w4 ,tw9+4 ,consi/+ ( "o l>ge %eet ( #ab butt]flies & two birds pr9t$ 9 bright colors4 ,"o small c>dbo>d ,model ,glid] ) descriptive illu/rat$ book %[+ h[ to make & fly !m4 ,po/paid 3 3 3 3 #ee;c 99 99 99 99 99 ,transcrib]'s ,notes ,obvi\s punctuation & spell+ errors & inconsi/5t hyph5ation h be5 correct$4 ,italic text is d5ot$ by und]scores & bold text by equal signs4 ,! ,,oe ligature has be5 replac$ by ! sep>ate *>act]s4 ,! fractions 1 & are repres5t$ us+ ! ,lat9-#a *>act]s1 b o!r fractions use ! _/ & - symbols1 e4g4 #c_/h or #b-e_/h4 ,! expon5ts #b & #c are repres5t$ us+ & respectively1 b o!r expon5ts are indicat$ by ! c>et "*1 = example1 v#ahe ,subscripts are simply enclos$ 9 braces1 e4g4 ,w#j4 ,o!r symbols t _c be repres5t$ h be5 replac$ by words 9 braces3 alpha1 pi1 !re=e1 squ>e root & proportional to4 ,! sk9 friction =mul giv5 on pages #aa & #abh h be5 correct$ by comp>ison ) o!r s\rces4 ,respectively1 ! =mul 7 orig9ally pr9t$ z f #jjjjjjgghl#icv#ahe & f #jjjjjjgghl - #jjgv#ahe ,9 ambigu\s cases1 ! text has be5 left z x appe>s 9 ! orig9al book4