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 ( 71* ) •72-4903 
 
 
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 Canadian Inatituta for Hiatorical Micrpraproductions / institut canadian da microraproductions liiatoriquaa 
 
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 ArehivM of Canada 
 
 L'Mémplair* filmé fvt rtprodMit grict à la 
 
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 " 7 '^' ■ .„■;.-. ^ ■ ■ ■ 
 
 La bibliothAqua dii Archivas ^ 
 natienaîat du Canada a , .' 
 
 Th« ImagM appaaring h«r« ara tha 
 poaaibla eonaidaring tha^onditlon 
 of tha ariginal eopy and in kaaping 
 fllming «éntract apaêiffleatiima. 
 
 quallty 
 laglbinty 
 tlia 
 
 Original eofilaa'in printad papar covara ata fNmad 
 baginning wlth tha front eoiMW and andliig pn 
 ' thfj iMi pas* wMi a printad or llluatratad impréa- 
 •ion. or tho baek bovar whon appropriata. AN 
 otl|or original eopiaa arofllmad baginning on tho 
 f Irat paga witfi a printad or llluatratad lmpraa> 
 •ion. ànd andUng on tho laat paga «witli a printad 
 or llluatratad impraaaton. 
 
 Tha laat racordad frama on aach mieroficho 
 •haN eontain tha symbol ^•^' (maaning "CON- 
 TINUED"!. or tha aymbol ▼ (maaning "END"). 
 Whichovar appliaa. 
 
 Laa iry4gaa suivantas ont été raproduitas avac la 
 plufjrand soin, compta tami do la condition ^ 
 dfla'nattaté da l'axampiaira filmé, at an 
 conformité émoc laa condltionc du contrat da • 
 /fllmaga. V ^ 
 
 ' Laa anamplairaa originaux dont la couvartura wt 
 paplar aat Impriméa sont filmés an commençant 
 par la pramiar plat.at an terminant toit par la 
 daitiiéraliaga qui comporta una ampraint* 
 d'hnprassion ou d'illuatrption, toit par laeacond 
 
 it, aaCon lé eaa. Tous lés outras aiiamplairas 
 originaux sont-fllnrés an coinmançant par la 
 pramiéra paga qui comporta una ampralnta 
 dimpraasion ou d'iNusm^tionl at an terminant par^^ 
 la damiéra paga qui comporta una talla 
 amprainta. 
 
 Un das symbdias suivants apparaîtra sur lo 
 darniéra jmaga da chaqua micfllicha. salon la 
 cas: la symboia -^ signifia "A SUIVRE", la 
 symbola ▼ signifia "FIN". 
 
 Mapa. plataa. charte, atc.^ niay bo filmad at^ 
 différant réduction retios. Thoaa too large to be 
 enttrojy included in one expoeure ara fHmid 
 baginning in tha upper left hand eomer. left to 
 right and top to bottom. aa niany frampa ae 
 required. The f oilowing diagrama illustrate tho 
 method: 
 
 \ 
 
 ( 
 
 1 2 3 
 
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 et do haut en bàa. en prenant le nombre 
 d'Images néceesairë. Las diagrammes suivants 
 Illustrent la méthode. 
 
 
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 1 
 
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- ' - '{AU rl<jli(H rfierrcd.) 
 
 ADVANCK FKOOF- (.S/t^pYf ti> rfrisii»!-) 
 Thia Preof la ««nt to you for dlMUMlen enlfr and on tha 
 aipraaa' undaratanding that It la hot to ba uaad for any'other 
 purposa «vhtftaooVar.-(.s,v .s.-. /. 39 ,/,»'/,• Ci,,/,/,,//.'». ) , 
 
 / 
 
 <fanadian ^orirty of (Tivil Cnninrrrs. 
 
 I-XI'AIII.ISIIKK l^■<; 
 
 TRANSACTIONS. 
 
 ÎJ.II.-Tli.i 84H'li'lj-. Mil iNMfy, iImiii ii>:i4i<>I.I lyi.-if r.>.|...ij>.|lil,. f,.r tliv fiioO iiml Kpliiiuiit 
 ', ' ' \, rtnliN) lu iii^jM^f tli> |iuMii-iiiN>iiit, j 
 
 ? ■ 
 
 ^ 
 
 /" 
 
 Thif jMifH'r irlll lir rriiil 011 Tliiirnifiif/ lin Vllh Miii/. 1|S87. 
 
 TiiK .stii'KiisruicTn{+: R)u;niK laciii^xk •nuiiHiK. 
 
 Hv J. \V. SciiAi II, M.A>!(»o. (,'.K. r 
 
 . Tlif lijicliiiiu Hridffv whh fiiM imllimil. aimiit H.ur jit-arH au'ii, liy Mrt 
 Vniilloriiv. ni' tlic Cnimiliaii l'ucifii- ICiiilwiiy. liiil It wun mit uiitil 
 NnvtiiilHr (>r ISSr» tliut tlio coïKriWl Inr llu" SniH!rstiuitiiro was 
 awardcl to lin- iNiuiiiiinn Bri<lL'<' ('... ol' .Mmitrial, witli Mr. ('. Slial'r 
 Siiiitli us ciiiiMiltiii}» iiiiiiiic.r, .Mr. I'. Alex. l'< U-r.-'iiii aitiiij; as cliiel" 
 fii^iifiir fur tlio Kailway ('oiii|.aiiy. Tlk' (l0«i^ii.r ol' tlie hrul^v is tlic 
 lat«' -Mr. ('. SliaUrSjiiilh; M. Traiili l»yM<mrt!, irscliiff assistant uii^çi. 
 nwr, li.ivinj: l'ull cliar;;)' dltln' calculai iiAis ai»! llic iji tails. 
 
 In ailoiitinj; tlic Iciif-ths liir tlio 'lifflrciil spaiis al lliiscrossinv'ol'thc 
 failli Lawrence Ui|lvr, tlicrc .vas nu pr/cwlcnt to lcu'hIc tlic ilcsifiriiT. ox- 
 ci'|>tiii;,' tlic lcii;:tlili wliicli liail Ih'cii aiio|itc(l l'or tlic Victoria Mriil^'c, 
 wliich arc Ds litiloys: lil spans .jii^i lîlOll. centre to centre of picrs, 
 with oiic rliaiinei span ol' :i,"((» l't./eciilre to centre of pierN. In tlie 
 linchine l{riil|jc w<* liave ci^lit .-pinsof L' 10 (t. centre to eî;nlre of piers, 
 twy spanMofSti!» (t. ivntre to centre of piers. and two elmnitêi spaim of 
 . 408 fl. «'litre to centre of piers. (Sec l'Iato I.) 
 
 Tlic Laeliiiic l»riil;:e li.';;iiis pro|H!i'ly at tlie tirstcrossin<; of tlio <!r»n<l 
 Trunk'lfailway, wliich is b>- an .SO IL tlironjili ni|.,|,.r. 'flic iiext crossinj; 
 is tlie Canal, wijicli is a swing bridiic :ilO ft. loiiu'. Tlic gênerai «IcsigU 
 j){ this swing liriilgi- is of tlie triangiiliir par#^-ii. knowii in " 
 Sinitli's iifficc as tlie " .Mcnonioiii'c " ty|H,'. Tliis swini; lias a 
 l»eariiig t!il)le tuming on 34 wlieels wliieli are plaeeiron.,a cir/iljir 
 track, lieiiigo|ieFat<.'d liy liainl |M)wcr or stcaiii |Hiwcr froiu tlic </iiire. 
 ^Tliere arc two el.iss«'S of ilraw spMns,^rini Inaring anfl centra l)cari/ig, tlie 
 ,'.ceiitrc-l>cariiig U'iiig nsçd for sp;tii,<i>f sliort Iciivllis iip to 1 .Til' fret ; for 
 spaiis of longer Iciujtlis, it is gcncral to ii.so tlie rini-Kearing. o/tlié lim- 
 bearing and tlie «(t'iitru-U'aring coinltincd, it luiiig casier to /|H'r«te tlie 
 riui-lMaiing swi/g (iir longer Iciigtlis. Tlic firsl spaii of tli^s/iitt.rn (tlie 
 triangiilar) \vii/ dcsigncd l>y .Mr. (Ml. IVgrani. M.A.S.t/lv, forimrly 
 aiwiftaiit to C.-f>lialer .Sniitli for tlic ( 'liicago, .Milvvuiiki,e aiifl St. l'anl Uy. 
 Tlic udvanta^es in tliis forni of swing are in liavijig |o|r riieliiieil cliords 
 at tlic ciid.syaiding in deflecting a |K>-sili|i' dcrailcd car \]Miichjiiav striko 
 tlie bridgj^ ulso in rt'ducing tlie arca c.\|)oscd to wiiiil pressure at tlie 
 cndsof Mcaruis, niakiiig it casier toliandlcdnring Uigli winds. Tlie 
 Hiip|i<isc|;l adrantiigc.in avoiding ail eouiitcrstrliiiis in Miisfiirin of bridge, ■ 
 wliicli/Mr. l'cgram liad at fir.-t sup|>o>ed to Ik- tli/eas«', l.s n<i| truc. 
 One particular'Uatiirc in tliis s|iaii arc tlic! rockcE/liiiks at tlie cciitro, 
 ■wliicli tend toci|Uulke theprestiurc on tlie tnrntaKie, niakiiig tbe slraiiis 
 onalic centre pîwts at uli t^cH alikc in aiiy onc pair. (!^ee l'"ig. I. l'Iato 
 Ifl.) The ciid.s of tlic aMiis, wlicn tlic draw span isclo.si'd, rcst on thc 
 /erownsof inelincd bcds, wliich arc set at a propcr élévation to giv«f tlic 
 réactions ncccssary for a Wani cnntiniHmsovcr three Icvcl sup|Mirts. 
 Tlie lieiglits àrc deterinincd by ealeiilatinn, anJ ample iiiurgin i» 
 
 niadc for«aiiy diwrepancics in tlicse lii-iglits duc to un«(iinlvexp ioiiii 
 
 fron'i tenipur.iture, luck of uniforuiity in the ela.sticitjr of tlicuiatcrial, or 
 any iui|K;ifections in the workniaiisliip. 
 
 After crossing tlic canal, wc conic to tlie river spans pro|K!r, wliich 
 consist, flrst, of thrcc 80 ft. dcek |(latc girdcrs, tlicii the eiglit 240 11. 
 deck spans. J/ 
 
 It uiight bo ntaU'A in regard to the jilatc girdcrs iiseil iu thc liaehiiio 
 IJridge, that tliey aro^all provided with rockers al the end supjH>rtH, so 
 as to allow any vtr^i^al iiioveuicnt in the girdcrs theuisclve» duc U> 
 dcflectioii froui passing loads, oMo neutraliic any iiiiporfections in the 
 worlfinanship, whicli would tend to briiig any uiidiic pressure ou tlie 
 bed plates or cxfialision roller». , 
 
 This lias bccn Mr. .Smiths Ihto praetice for ail girdcrB above SOfcct, • 
 andwas first^iiMod for thc lX>iivoK,aiid Jtio Grande Kailway in 1884, 
 
,..f 
 
 ■f 
 
 ■..i^ 
 
 \A 
 
 ■:H- 
 
 TIh* ifcncral ilt>Ki^ii of tlio dtt'k ciniIim iHtlic ilouhltfiiiU^rM't'tiôh l'riitt 
 Triiw."' 
 
 Tlii> twii MVKtuiiiH Wu\)i liiliri'Jy in<lr|K-iiilt'iit oryncli (>tlii'rtliriiu^lii>ii| 
 CCI- l'ialf III). Wlicru (lie ililiL'iniaU rciisi tli« ViTliciil [«wIh, itiVri' 
 \y a pin riii<fkiii<^ llirniiuli llic inmi, iivikiii); tlic {iex iii twn loii);tli'<. It 
 i» » iiiiilti'r "l'rt'^int tliiit iliix iinictici' luis liofii iiAcil iniliM'riiiiiiiatcly 
 liy llio Kiiiiiiiirrx iii 0\r S|«|.'!<. willi<ii^( aiiy rr$:!iril ax 1" ils |H'r|iiiii>iis 
 itfU'l»'. Tlli^ liaj IdVii tlii' iM-H'. liir ('Xaiii|ilu, t" «iii'li lar>;i' .'■triictiirt'!* 
 a> thi' PlatKiiixiiili IniilL-r. in wliii^i llicti- arr ixfU 50 W: Unvj; on (viitn's, 
 J^liviili'il iiilo hall' Icn^tlis !■>' tlic ti(-< cro-i-iiiij; at tlxir niiddlc, witliiiiit 
 any |>ri>vii<iiiii fur tlic cfliTUtiirili^toriiun <liK',t)> Htrain in liir nicniln-m ; 
 tlii' «.'IVi'Ct ol'a ii>ail l'oniiu;.' un a structiir» tranu'il in (liii>'lnanurr ran liu 
 laxily «hown (Mv Fii: I.. l'iato III). Snpiosinjj tlic'-tru-M'» tu lie l'ani- 
 IkTi'cI wlu-n tluTf i» nu xtrain in any nicinlur. llic iiitvrwftiun uf t|i)j 
 tio ir> at !«>inc |Hiint Ih'I'IW iIic <vnir4' iif tlic |ll>^l. Nnw, wlii-n tlic Inail 
 l'iiuiç!' lin tliopan, tlic clinnls tcinl to lnTunn' lioriziiiitiil, tlic |hi!<Is k-nd 
 lt> li'winiv vi'rtie:il, lirin^in;; llic inlcrwcliun "1" tlic lii'K witli tllé|Ml^lH 
 niorc ainl untrc lo\var<l-> tlic ccnlrc oTtlii' |>i»t, iiiitil linally. wIicik llie 
 cntirc cainlicr i» takcn mit "1 tlic tru»«. tlic' intcrwitiiin niuxt lU'ir-sariiy 
 Ik! at llic centre iil' tlic [m^t ; llic nniimnl <il' tlji» niovunicnt ilcpciiiU nu 
 llic lcnj.'tli i«f llic jBiiiil» Hnil thc ilc|itlè ni' tlio iru^H. In tlii' -4t» tld 
 >|inns ut' (lie Lacliine liriili^c, tli'i* nnivcinciit aniuiints to aliuiit \". ami 
 ha^ bct'ii |iriivi<]i'il liir liy niakini; tlic liolcs in tlic \tn^U I" hirpr tii-iu ■ 
 llic |iiii, lliiis ailowin^ aniplc niovcincnt t'nr tlic pin wlicii tlic Kiail ciiuicx 
 (II) llic liriilgc. Tlii." UKÀcuicnt ci>n U' noticcil in a striicliirc at aiiy tiuio 
 wlicrc thc pin ir^l'iccjlo niuvc. un in thc Lacliinc Hridfic Wlicrc tlic pin 
 i;» iiKlJ'rcc M innvc tlic.ili.'<tiirti">ii'' niij.''t nuccsnari|y takc place in thc 
 iiicnil)ci-s tlictiiw'lvcs; àiiil. niiiriovcr, I <|ilcstiiiii tliis practicc wlicrc 
 it hus Ihh'Ii iIiiiic witli a vicw U» lii-urc thc piwts liir liait' tliçir tottil 
 Iciiutli, «ml cinIciiliT llnni a» fixi'il cnilctl wlicrc tlicy arc liclil hy thc 
 «liajriinalsat thc centre. , ■ 
 
 Tlic iicxt|H)Hi<in oftlie hriil^- IuIh' consiilcrcil itfcthctwoitiO rt..H|iun!i 
 ami two 40s ft. npans l'urniiii^ limr ci>titiiiii(in> .<paiiH ovcr Hw Hup|Hirt8 
 (_s«'C IMatc I V )'. 'l'Iicrc wcrc, iwii cicsifrii» priipnMil licsiilctt thc une tlint 
 wan linally aclnpicd (m'c IMatc V ». Thc ilcsiùn as ailnptcil i.» kn^iwn in -^ 
 .Mr. Sniitir." office «!< tlic '• Flyini.' ("'aiitilcycr,'' ami wiis''lir.-t phip ..ii'd 
 ti.rthc .Stoini Kiiii.'liriil'.'c ovcr thc IIiuImiii lîjvcr, in State ol' Xcw 
 York. As uhmI in thc liachinc Hridgc it is, pro|H>rly s|iciikinf:, ny can- y' 
 tilcvcr hriilp . as tliç spans aie contiiiiiuiis. The eaiitilcvcr pfiiieiplc,k 
 uscd licre l'or cnetiii>; tlii: liridfîc only, whicli is lifiiit oui l'roni thc jiicr.s 
 on cach siilc, llicciidsbcinjij'iin 'ci attlic centre wlieii thc tiiiaicoii|iiliii<; 
 is niade, uml thc >pans heconie coiitiii»i>n' ovcr livc sirpiMiits. Tlici ad- 
 vantajrcs of thc l'alililevcr principle ave only iiï, sa*iiig in llii' crccljion/' 
 thcrc iH'iii^ no saviii;; in thc «T'i^lit. as wc inci'vly niakc a ditrcècnt 
 distriliutioii of tlic malcrial tlian We %i^il in ordinary dis<'iiiiiiectcd 
 spans. lii a contiiuious jiirder therc is ncccsNirily a saviiiï; in thc Wcij^lit 
 uvcr tlni iiicrs, as wai» thc cSse in thc Lachiiie Kridtic, but thc saving 
 in thc mode ortlic élection is thc principal item to hc considcrcd lii,>rc. • 
 Tlie uilvaiita;:e ofii-iii^ two centre pier» iiistcad ol'oiic Would lia'vt» l^'eii 
 a consiilcralile >aviii'.: in tlieco<t ol' érection, luit iiol >uHi(;icnt to euun- 
 lerlKilancc thc iiicrea-cd eo-t ol' iliè extra uiasonry ; thi» was thc |Jriii- 
 cijial reason why oiie centre picr was oiily iwd iusti'ad ol'two, as shuwn 
 iuFifîl. l'iutc V. 
 
 In s|K'akiii^ of caiitil 'Vcr lirid'res, it uijglit lie lu'Kc'titat.'d tliat tire , 
 lirst eautilcvcr hrid'ji> huill in America was ihe Kciitncky Hiver Hridge 
 liuilt by^Ir. C. .S. Siiii,th in 1870. .Mr. Sniitli aiso built thc.Minnchaha 
 cahtilcvcr in IHSl, loiii; belorc tlic MaJ:Hra'é.intilcver was cvcr tliou;;lit 
 ol'. Thc Kciitueky Hiver Uridjjc is a wiJfidcrl'nl structure, l'roui tlie 
 l'act tluit it is renlly thc lirst cunti^uoiis <;irc|er tlidt was cver built in 
 tliis counlry, and is rcinurkablc aL-o l'roni thc l'act that iusteiid ol'bcinjî^ 
 coutinuou!) ovcr liiur sup|M>rls (Sec l'Ialc VI.; it lias in points iA\ 
 «outra-flexurc lixcd by curtiiii,' tlic chords al'ter thc bridijc was crcctcd'.' j^ 
 In it lelt«'r ol' .Mr. Sniith'si written two years bel'orc thc bridgB was 
 built, lie .siy s: " I fecl w> confident of niy calenlations of thc contin- 
 '■• non» }:irder tliut I now pro|Kisc to eut thc chords at tlicir jMiints 
 "contraflcxijrc, tlius fixinj; lliiw |K>ints beyond a rjucstion of doubt." 
 This stateuieut was thc lorcrunncr of tlic Kintucky Kivcr.ltridfrc, in 
 which thc jtoiiits nf coiitra-flcxnrc werc fixcd at. * (Sec IMatc \l.) f he.sc- 
 points of contra-flcxurc could liuvc Uicn fixcd in tlie river amis instuad 
 of tlie nliorc- aruisi, «nd it is a curions fact lliat tlicy sliould not liavo 
 bci'H fixcd' in tlie river arinn, as was BubmMpiently donc by -Mr. Smith iii 
 thc Miniiclialm cantilevcr, wlicrc thc 'iKiiut of eontra-fluxuru is fixcd in 
 thc centre of thc river npiin, tlicrc boin^ two shorcs «rni» and two river / 
 anus witliout any uiid H|ian huiig froui tllfc ends of tlic river aruiH, as in/ 
 tlic Niagara and St. John caotiluvor bridges. / 
 
 : ^ ■ I ' 
 
 ;* 
 
 V 
 
 •. %. 
 
 '. TUBroNTINUtlIlt lilRIIEIt!/^s.~ .^ 
 
 In Biiy liciiiiÉ continuoiut ovur any njliinlHT of suppiirts, wlien any 
 
 flexiirc tàkcs place _, = /.. , in WliieU: " . 
 
 ■,►" . ■>,;///, ! ' f 
 
 M, is tlui U'iidin;.! luolm'iil.al any imint iirtiic U'ani. 
 
 S. iH.t'hc radius of eur\aliirc of thc bi'ain at lliat |Kjint. ,. 
 
 K. is tlu' uioduliis Klaslicily nf the inalcrial, 
 
 l.iiVfiie nioinciit.of iiiertia of thc cross .•«et ion of thc bcaui at that 
 |)oint. ' / 
 
 lly assuinin;? ail tlie supJKirt.s 16 K' Icvcl ; and a.M.snniin^' •; K " niid " I ' 
 to Im' constant, ihe ihmieni of Tlirce .Moiuciits uiay Itc Mbiained, and 
 J^uivciiin ail lexl IsHiks on .Vpplied .Mwhanics.' llowcver, it-was not 
 uiitil .Scpteml>«r, L'^T."!, vilnn l'rolc.«..or .Maiisliclii Jl^rnnianjpivc, intlic 
 London IMiilosophical Mai:a/.inc, thc lorniulic' lid' a b.anlk'ontinimus 
 ov.r any iiunib. r of |e\el su|i|Hiits which aicat ail practicaHlc. * 'I^m: 
 lonnulii' arc IIS l'oUows :_ . .• ' ' 
 
 Foruiulic lor obtainini: |iiei- nionients aiid reactions, à"^ i^pplicd to tlu- 
 ^l'our eofitinuous spuns in tlu| l.acliiiie lliidgc. 
 
 ■; ■"-ai'-i' i 
 
 
 I. 
 
 
 ■•t. 
 
 •■m" is thc iiunilH r i/f any picr. ' < / 
 
 "r" is ihe ii'uinber of any liu'r loaded spaii.*'^ 
 .M is any picr moment.' J, ' 
 .*« is llic to^al niinilH'r of .«iians ..|. \ 
 
 \Vc havol'or Picr .^lolllenls wlicii m t -, 1. 
 
 . . ;V V / / '■,-! r-J(,(Tl)r« 
 
 )• we bave, 
 
 .1= VI-, \ik-:\lr yk 
 
 A 
 
 ,1, SikOi N'ik I-, 
 
 A . 
 
 When 
 
 in which 
 
 
 .1' /'AVU-Â-'f .. , II* ° Ij- 
 
 V d'ii'iiiti ^tlic load in anyispaii 
 
 /, dcnotini; thc Icii^th of that spaii. i 
 
 a ili:-l.iiii- ■ l'roni n'eaivst l<>ft liand sup|4irt to tlic'load "P," 
 ficcussariiy a conecntratvd load. 
 ■ - -,. ■ <■, = n :.•, = ! V', = - (ï i -i )() - ;t;il.)i. 
 
 • " " c, = I +;! + i/i V (i.f i)| =/i i:;^2iii(i. 
 
 which is 
 
 S,- (iti li.aclei|-'j»aii) 
 
 ^V .L 1 (lu Inailcil ^jàii) 
 
 A» (In itiiloaiUMr.-iaii-;) - 
 
 SIIK.VIIIMI KiiIfl.'KS. 
 .V, - M, + 1 
 
 1 ■ + '/ 
 
 Ir '» , 
 
 1/ 
 Mm - M,„ 
 
 l„ 
 
 .1 ■ , Il •""' - "''" - ' 
 
 ^'in (in niiloaileti riiiins) - , 
 
 - ■ -' 'm — l 
 
 in which 7 =,7' (1 - /.) ; 7',= 1' « *•. 
 
 S, denutcK thc slicariiig force luimediatcly to thc riglit tif thc iicarcst 
 Icft hami sup|Hii-t, and S, + 1 dénotes the slicariii;; force iùiuiediatcly to 
 thc Icft of tlic ncarest riglit siïjiport of thc loaded .s|>an. ' ' 
 
 S,„ and S„, appl/to the nnloaded spans in thc sanie uianner. 
 
 Thc.abovc l'orinul:c arc frivcn by J>ub<iis in tlic " Strains in Frauicil* 
 f^triicturcs," page 135, but uiifoitnnatcly thc siL'iis + jand - sliould 
 be reveiscd. _ , '. , 
 
 ïlie principlcM of thc dcsifin for tlii!*l'our c/intiniious spans, upun 
 which. the calculations Werc based, are tlic strains Irôni dcad wctifht 
 which arc caleulatt'd as a canlilevereacli w.iy l'iom "W' (.sec Plate IV). 
 After'thc dcatl weit ht is svvun;; complète and f7ro|icry adji'i.stincnts arc 
 lIjuMible tics eacljway lidin "W, ' and adjustibic 
 thc lialaiieiii>: spi(ns jit "A"; tlii^seetion "XY" on 
 in pUec when tlij' limr s|>ans aet a» eotltiniinns as 
 fat- as livc load is cor rcriicd. Thc ciil^ulations lor livc load strains werc 
 tlieii uiade iii aecor lance witli thc formula' beforc given for a girdcr 
 continuons ovcr.level supports, ami thc two werc ciiinbincd. 
 
 Thc <dijiH-ti«iits to any conlinuouK girdcr arc : Ist — thc uiodulus of 
 riasticity "K" is mit eiinstant ; :?iid — the uiouicntHlof incrtia "l" is not 
 constant; 3rd — thc f iip|Mirts aix' not nccciwarily Icvid. .TIic§o objections 
 will bo diseusscj in ird)'r. I ^_ 
 
 Ist. — The uimlulu* of elasticity, as îs wcll knoWn, lia« widc uiargins 
 of variation in thc su nie uiatcrial, but by rigid inspection oftliomatcrial 
 at the niill this vai alion way be reduccd to a miniuiuui. Mr. lions- 
 carcn gi vch thc uiar} in for variation of tlio uioduiuH of elasticity of iron 
 at percent. Fur uiild stccI, which is a far lutjre homogcneo(i»iuetal 
 
 .. ^^ 
 
 ' 4iiadc by nicaiis of ; 
 
 hvAk at the cmis of 
 
 .top chord is viveted 
 
 / 
 
\ 
 
 7 
 
 .^'' 
 
 
 * tlwn iroo, tltin irnirgin iiiny bo ^ry inneh rcliiNd, OF cnMriio|iiti|irlir 
 ■^ viiri»tr.mH in tlu- p«r.v*i.iain. ,.f ..arimii in Hfvl i.rojuo.^ wi,l.. muidi,,, in'' 
 
 it>* .Itielility, Init « ri>îi.l inx|io<-(ioM »( tlio niiji <m|. piunl iijjnini tlil*. 
 tii.lhr Lmliino UrLIp-Vn-cat cir.' wn« mkon in wnrin» a Miil.l un|i;>rin 
 VK-.I «ith nn lihhiintr mV hUmU ««.tHM» lU willi n ■lurtî% of ik |h r 
 cVnt. h. l-.'ilInni.l.i-K. Th.- t.si. H.'iirs,'.,n.-Btl>' niH.lo nn «mu- .i' t|,.i 
 Jiihsiz.a ni.inUr« i.l l'ill-lnir-, l'.nn, hI.J,w,..IU;.. .ni.tori.ij 1^, 1,,» th.. 
 naiMit tw wlnn t.An.J in sniiill .i-vîm, „,, 'n„, „„„..ri«l «•,.../T,.nH.l' tô ' 
 !«,• 1.11 tliat .-..iil.! 1... .I.sir...!, i"«'l ll"«' Si,...| ('.>«,,,a„v ..l.S-otii.n.l .1. „.rv.. 
 irniit priilM- in lurnisliin..' a iiuiCnrin Ht.rl, s<.nirn.in« wliioli ic n.)( r^.y 
 tn..l,t»in., Tl.rirpr.j...s. i4,|,,.si,>n....,i»()|H.n'n..artir|.r.i,.,-s«. 
 
 L'n.l.— Tlio ni..in.'nt..^ ..l' iiirniji in tli.^C.rnMilh- nr<< a^^nni.J il» .•Ôji.«»^int 
 Kivr r.Hn)tH «flii^Ji arr n.tinly nn tlir kiH' si.l... u'ivin^ -tiarns wl.icli an" 
 ^ >rrPal«r thi^ tli.y àMm.lly u..ul.l 1k'. ,.,.|H.,.iaily nv.r lli.- pi.Ts. 
 
 :tr.i.— 'IMio siip|H,ris wliioli n.ay lu- a^uiiifil tn l». ont oF l.vrl i-an b,. 
 lit anv tinio a.,l,iiii.l...l l>y ans nl'ili.. ailjiistil.t,. Ih-.I» at lli<- .-niN nC tlic 
 
 • bnlaïu-ln^- Hfmu. «t A (r«' l'hH-. H'). an.l anv ina.-.Miracy in il... 
 
 - dlMril.ntinn nlM.a.l wrii-Ut oan !.■ al any tiu.r nmiml in il.Vvariatinn 
 «•■'' "^""^ '" ••"•\''<« »« llu' «•<»tr.' nf tlu- cl.anm.i«)ani.af\V , 
 
 (H" l'iat.- IV.,). ..^., ^ , ' .: 
 
 »> Tlu- tl.nn- ol,j,rtioiw m tli(V,.nntinnnns i-inl.r an- v.-ry «-rions an.l ' 
 wn.il.1 l.nv,. .i.vl..nl.t.'.ll^ iVril 'snffici.ntiy slr..n^ t-> l.av,- i.r.vcnU-,! r.si».r " 
 H .•nntnm..us fr'ft.Kr fur tl«4 s,,ans. I.a.r it Inr th.- ,lili..ns ..n.l.-r 
 
 ^ wl.i.l. ll.is .I.s.^ru «N.s ina.li-, ;.\,w.Msi:l..rati..n nftli.-s,- will at niK-,- slm,v 
 
 thaï th.- |irnl.hi„ 1, r .■ln>inK lh,-W. .-haini.-! .-.pans w;.s i-.-rtainly sniv,-,! 
 
 III th.. in..,-<t sci.nl ili,nia»n.r. «h.i. it is Ik;|-„,. i„ niin.l tJiat Hu- p..srii.'.iw 
 
 «l t,h.. pifis «vr.. ail lix..,l, aiiJ il ivas ini|K.ssll,|,! t» nso liiU-work in, 
 
 ' raisin;; thi' twn l'Iianni.l ..-pans. 
 
 Tlu. lrus.<,.s for th.. iiiiiunns -ir.h-rs, il will l.>- nnti.-t-.l, an- oC il,,- 
 
 «Inubl.- int.r.s,.cliMn ty|M.. «s in th.. .-i-^-bt 210 f.-.'.t .hrk s|î„.s. A,.,H«stinn 
 uii^'lrt 1h- rais4..l as lÀlh.. |H,s>il.i|,ty nC inakinj; .-..m'c-t .-ali.nlalJ..ns nlthe ' 
 Urainsin tlK-eniv.,! ,«,rli..ns..ttlH-,|,ann..| s|«.ns, inasunn-has tn..j|w.. \ 
 sysl..iiish.ro.c.inl.in.. tli..irstrainsnnt-inlotk-nth.-r. Il «onl.l U.- ini- \ 
 |H.,siblo m do sn it th.. ./al.ulati.M.s w.f.. ii.a.lc- fnr .-a.-h svst.ni soparaUly. 
 but lier., ihc- cal.nlatinns fur th.. two syst.nis wt-n- oairù-.l thr..n-li jo- 
 gi-ther. un.1 th.- w.rk was v.r^i miah siniplili.-.I in nsin- th.- urapbical 
 ii.cth.Hls cntinly, l'..r .alculatii.K ibe «trains in th.- cnntinimus î,'ir.l,-n. liir 
 
 • tlu- I-achin.- Itri.lg.-. As to tho ni.lhn.ls nsc.t in tt,e .«.Ic.ilatioi.s, tlu- 
 aulh..r,w..sh..sins:.y that Mr. M.K.re, ..Cffaint l^iiis, bas re.-.ntly pn- 
 lmr-.l il llthn^trapli, whi.-h shows alj il.,- c>..H-ntials n.-ccssarv t.. .in.l.rr.stan.l ' 
 
 th.- n.t.tho,U iiM- 1 in a vcry .....luis,- li.rin s...,,„.„t|y I.Jr,,. lull détails 
 
 as n-garils thc (•al.'ulalions will 1k^ .miittcl. 
 
 - Tlieunit.strainsnso.linibc.lctailsttrci;ss..ntiallyasfullows: '' 
 
 .'<i.'.l(!. 12.(100 |hs.p,.r s.|uar.- in.-h l.,r Liislun. 
 Ir.iH .(.. H.OOO " " <- , * « 
 
 Th.-only I. iïsiMn in.-ftib rs Ihat aro imn ah- .•oui.t..r-r...U an.l tho win.l 
 bva.M.-. F.irthcwindbracin-tt bi-ht-r unit strain Wa.s usi-d -Tho ' 
 cM,npr..>sio„ n...n.l.rrs w.r.- ail lijjuh-jl.by tho " Ifankiiu-n.mscarcn- 
 lonnnla-, wbi.haro ...ruiiily tl,o;b..st f.frii,.,|,B in' us,., as th.-y giv.-/ 
 rcsults whieb aLTo.. mon- n,arly with thc rèsult' ohtaii.cd fr.ini aot.><d 
 t.-sts than any i.lh..r fnruiukc. As uscd in tho Lachino nri.k'.-^ tho 
 b.riiiiiiii- arc u>r htct-l. \ 
 
 /' = 
 
 - • 1 + 
 
 'i* y 
 
 T- 
 
 -.7 
 
 >i^ 
 
 A 
 
 I ni)(Mi-4 
 
 fur lixc.i cii.l-. 
 
 /' = 
 
 + 
 
 1 + 
 
 .•||J0«0 ■ ( • 
 KKinn 
 
 ÏJIMKl X r - 
 1000!) 
 
 l'or une livr.j cihI ami . 
 
 >iic |iin cmls. 
 
 ïnrttt-o pin cii.|<. 
 
 IsOOO 
 
 Tln-sc Ibniink- an- sn wcl] knoin ihat no ,-xplanàtion is m-ccs.sary. 
 The lOOOOir.s. (nrstivl in tlu- niinicrator issiilistitntid l'or .8(tO(l Ibs. lor 
 Iron, as ^rivpii by Mr. H.>n.si'arcn in his rc|Hirl tn tho" IJ(,ard «if TrusU-cs for 
 thcCincinpati.SoHlh.rn Ky. Asiho inattcr nf j;iiard rails in railway 
 bridircs bas now kc.nne so vcry iinjiorlant. it w<iuhLi»-rliaps be wcll t.> 
 say tbat whcn thc Vicbinc Itridgo isc.>uiplcl,..l. a traiihof cars wuld hc 
 . run nffthc track fi.rtb.cntirc Icn-rth .if thc bridirc, wj[lhoul thc |)asscii;;.'r.s 
 kiiu; awaro ..fit. Thc tics an; spaccl with 4 inch ii|Hniu^s, and tlu- 
 whccU are fçuanlcd by two bcavy ;juar.l rails on cach sidc«f thc track. 
 Thc only ac-i)filunt that ciiilil possibly bnp|H>n t« a tr«IJt'',(fiDar.<on tlii» 
 bridu'L' is, that thcy ciul.l bo bl.twn bo.lily oll' thc trackjpnivi.lc.la west- 
 ern .-yclone «h.mld happe» lo visU this secti.m of thc country, wliioli is 
 not at ail probable. 
 
'•^rn^m ' 
 
 >$««;- 1- ' -«iiii»-} >' 
 
 T^mr 
 
 '"Î1W^PF«""W""WM^|» 
 
 ' ^^'■•■^^^f'«J«I^^^^P^^!FIJ5î!W^ilWW^"^^^"WP»"P 
 
 *<:^ 
 
■"« 
 
 f 
 
 \ 
 
 ^ 
 
 'à •"' 
 
 "^ 
 
 -X