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ADVANCE PROOF— {St//>jnf to revision.) 
 
 This Proof is sent to you for dlsoussloci only, and on tho 
 expross understanding that It Is not to be used for any other 
 purpose whatsoever.— (^i^.-S../. 39 of tlu- ConsiituiUm,) 
 
 «r«n«ai«n Society of Civil (»:'n«in«i$. 
 
 KSTABI.ISIIKI) 1««. 
 
 TRANSACTIONS. 
 
 N.B.— The Society, as a lioily, .loen ii"t liol'l i.«elf r(s| oi;i.llili' fcr tlie fact! and opinions 
 Btateil in any of its publiiations. 
 
 FKAZIL ICE. 
 
 ON ITS N ATI' UK 
 
 AND TIIK I'Ura'KNTlON OK ITS ACTION 
 IN CAUSINO FLOODS. 
 
 By Gko. W. Hknshaw, M.O.S.O.K. 
 
 The subject o<'tiii,s yj.\ky is (uie dcstiiua, I bi'lifve, to becoum of iii- 
 creasint! interest to Ei Jieeis in Nortliern cnuntrir^. enpecially to thone 
 engas^ed in works liiiljie to l>i' att'.rtiMl liy itv, wlietlu'r tliroiijih direct 
 attack (H- tbrou-li tioods euiiscd by llie iirn-t oi its niov.'nients. My 
 object is to define tlie true natiin' ol Trazil. and to si|i;nvst a inetbod ol' 
 dealinu; with it, si, as t<i jiri'vent its nion' liian suspected ajjency in 
 producing floods. 
 
 Whether the vast masses ofcoinniinuted iee, wliieh in |)laces are found 
 to underlie the surface ice, are composed of trui' siil)ai|iUHiusly formed 
 ice, or are made up larsreiy of drifted snow, and the broken scales of 
 surface ice carried down by tlie eurrenl. is yet to be positively deter- 
 minea ; still, from the evidence which i xists of enornions c|iiaiitities of 
 spongy looking ice seen rising from the bottom, it is reasonable to conclude 
 that whatever may be tlu' proporlioii <il' these >iib-tanees true frazil is, 
 really, their principal eonstituenl. 
 
 Now, for an engineer to meet a difficulty with iiitellitience and success, 
 it is almost .essential to understand the actual charac'er of the enemy 
 against which he is to contend. To s]icculate on this bring-' us some- 
 what out of the sphere of the practical engineer and into that ofjjhysical 
 science; but we are often compelled to this course when scientific men 
 neglect the subject, or h'ave us in the dark. 
 
 That 80 little of the nature of frazil is known among engineers is not 
 surprising, when we find that the haziest notions, if any, regarding it 
 pre\ ail among our highest scientific autlioiities. 
 
 At a meetinu of the B. A. A.S., held in .Montreal on the 1st September, 
 1884, in presenting a paper on the subject, the writer was confronted 
 with a specimeti prepared by Sir William Dawson, showing his idea of 
 the formation of frazil icfv It was a piece of lead iierforated or cut into 
 deep tl.'kcs on its tijiper surface, by the action of a current of acid 
 
 passing over it. 
 
 As explained by the President (Sir William Thompson), frazil was 
 supposed, similarly, to be the product of currents of water passing over 
 and disintegrating solid anchor ice, exposing, as he expressed it, its 
 'bones," just as rock is worn into irregular forms by the removal of its 
 softer parts. Now. it is difficult for me to conceive how anyone, practi- 
 cally familiar with the appearai.ce of frazil, conld attribnti' its minute, 
 needle like fragments to a waterworn origin, or believe that a substance 
 80 developed could be produced in large quantities. We <lo indeed, in 
 the spring, see ice disintegrated to its boues, and falling to pieces, but • 
 that is only when it is exposed to sun and air. and when the formation 
 of frazil is alrea.ly a thing of the past. This experience convinced me 
 that science had as yet no information to give ; and that up to the present 
 the best authoritiiwregarded frazil merely as a curious formation, of 
 rare and limited occurrence, 
 
 I think many of us are hasty in assuming that all is known about the 
 philosophy of ice formation. Tyndall. when he overthrew the theory 
 of RumfoVd, did not, 1 think, exhaust the sol.jeet. We know that water 
 can be brought above its boilin-iioint withoni < huUition. and we know that 
 it can b<! brought below its freeziiei jioint without congealing. We 
 know thit superheating reiniires i.ressure, but how much do we know 
 of the conditious accompanying su|)ercooling V 
 
 I believe that ice never forms in water without an independent 
 nucleus ; that when it appears free on the surface the nucleii are supplied 
 
/ 
 
 / 
 
 by minute iiaitidoH iif vdjxir, wiiiili, tu'eoiiiinv; frown in their aspent 
 liili back iiiMiii till' wiilir, liiviii iicrliaps. the very stars wi'ii in a block 
 ofici- wtion iiiclti'd tiircm<;li a lens by tbc sun's rays. 
 
 Tbat tVii/.il, liko anchor ice. livrnis nu'lcr water scums unqufstionable. 
 >lr. Frank ( rilbcrt, en^'inccr. contractor for ik'c|)cnin|{ the channel tiirough 
 the (iallnps i;ii|ii(l -tal 's lliat be lia< i-i-sed in a boat ovir >;r.at bi^ils 
 of it. coverinu the bottom in (hnso masses of a s]ionf;y a|iiM'araTice. 
 through which his Jiole swept with scarcely perceptible impediment. He 
 also observed it niion a wire rope e.\tendi-d beneath the water, between 
 liis ves.sels, lonkini; like bundles of iron lilin-js lifted up by a masinet. 
 In this case be noticed the curious fact that Jiarts of tbc rope were bare 
 and others covered with the growth, which scenieil to negalivi' the idea 
 that the cold had been conducted through (hi' ro)ic. Under the 
 eirenmstaiiees it is )ilain that the eX]icisnri' of the end- of thi^ rope had 
 little or nothing to do with the formation oi the i<'e. 
 
 The conclusion I have come to is, that frazil ice is formed in currents 
 cold enioigb not only to ]ireserve its crystals but to induce their 
 formation. 
 
 Hut why .-hould it grow luxuriantly on one spot, and yet rcfu.se, as 
 wi' have .seen, to grow u)ion a closely adjacent sjiot of a character pre- 
 cisely siir.ilar ? 
 
 Well, that is a iiuestion yet to be settled : but with your indulgence I 
 will try to oifcr an exi)lanation. 
 
 All who have observed the action of tine drifting snow, when driven 
 by the wind over a plane surface, such as a roof or a railway platform, 
 will have noticed that it does not swe.']) along in clouds, or rolling 
 volumes, but in long rifts or streaks with bare spaces between. With 
 every lull of liie wind these streaks rest for a moment, to !"■ swept away 
 by a succeeding blast into new combinations of a similar I'orm. acciuding 
 to the variaiioiis, in force and direction, of the wind. 
 
 Now it is evident that these rifts are jiroduccd by the small iiox(Ualities 
 of the surface of the plane. 'I'hat the bare places are where the wind 
 is least obstructed ; and that the snowy streaks are the eddies where its 
 force is partially obstriictcil. Now if this is admitted, we are brought 
 to the important conclusion, tbat if the obstructions on the plane 
 remain ui. altered, and the direction, \ lunie, and litrce of ihe wind 
 continue uiiehanged. the -treaks of snow with the spaces between will 
 alwnys oecu|iy preeisi'ly the jauie position upon the jilane. 
 
 If we now apply the.'^e observations to the flow of a river, we shall 
 find a dose I'.pproximatioo to sudi supposed conditions. Vnr taking 
 the case of a stream with a rocky bed, we have the more or less perma- 
 nent obstructions 1.11 the bottom; while, i.nlike the air, the volume, 
 speed, and direction of the water are but little afl'ected by superficial 
 influences. 
 
 The bottom otsujh :• river jjre.sents a confused suecL.ssion of irregular 
 obstructions, around, over and between which tb water rushes in every 
 direction jiossible at once, and at every variety of speed. Aloni; its 
 maiu channel, greater freedom gives the river current its highest velocity, 
 80 raising its volume at vhe stiP ■•• readies tliat l)ackward currents or 
 eddies are formed at its edges 
 
 Looking lit the troubled tumbled surface such a river sometimes 
 presents, one is tempted to believe it a hopelessly involved chaos ol 
 complicated motion ; but ihere is no chaos there. Every movement is 
 made under as strict a law as governs the piston of an engine. Every 
 bulge or swirl that we notice at some jiarticular spot comes from the 
 Relf-samo sunken rock or cranny, and each would rejieat itself precisely, 
 were it not for molecular variations, which we will not here take 
 account nffurtlier than to note that they modify, in a minor way, the 
 results of which 1 am about to speak. 
 
 Bearing these facts in mind let us take a horizontal or piano section 
 of the river. 
 
 Here we have in the currents .'^o intersected, instead of the long streaks 
 seen in our snow drift, an irregular network with meshes of every size 
 and threads of t very thickness. The threads represent tbc currents, and 
 the meshes the comparatively still spaces enclosed. If wo wish to 
 represent the molecular effects alluded to, they may be sliown as a sort 
 of fringe of eddies along the sides of the threads. 
 
 As in the case supposed the general plan and position of the network 
 is permanent, and as we know that water is a bad conductor of heat_ 
 it is plain that a sudden cooling of the _water uji stream would cause 
 the threads of the network to became colder than the unclosed meshes ; 
 while the reverse would be the ease on the water above becoming 
 warmer, so that objects placed, the one in mesh and the other in tbc 
 thread, would be affected differently us to temperature. 
 
their ascent 
 11 ill a block 
 
 ueatinnable. 
 iiiultlirou^h 
 
 iiniit IhmIs 
 u|iiM'uraiit't', 
 (liini'iit. Hi'. 
 ir, bi'twci'ii 
 
 a tnnsriii't. 
 ic wiM'i' bun' 
 ivc tlic idea 
 
 Under the 
 le ropi' liad 
 
 I in currents 
 ndiiec their 
 
 t refurte, hh 
 iracter pru- 
 
 iidul^i'iiec I 
 
 vhcn driven 
 
 ly platlorni, 
 i, or rdihiiu 
 •on. Witifi 
 ■ swept away 
 11, according 
 
 1 iiiet(Ualities 
 e the wind 
 ics wliere its 
 are broui;hl 
 n tlie plane 
 of ihe wind 
 jetween will 
 
 er, we shall 
 For taking 
 lesrt iiiTiua- 
 tlie volume, 
 y Huperticial 
 
 iiof'irrfjiular 
 
 ■<hes in every 
 
 Aloni; it!' 
 
 hest velocity, 
 
 currents or 
 
 r sometimes 
 ,'ed chaos ol 
 movement is 
 lie. Every 
 les i'roui the 
 icll' jireeisely. 
 t here take 
 ir way, the 
 
 jlano section 
 
 e lon<^ streak:* 
 )f every .size 
 currents, and 
 " we wish to 
 wn as a sort 
 
 the network 
 ctor of heat 
 would cause 
 ised meshes ; 
 vo becoming 
 
 other in the 
 
Now for iho formntion of frnzil. 
 
 Tin. rivor is .<»M ,lown ..-arty to .•onpclution ; ihrr.. ... «- k,,..*. a 
 very m.W n-ar^M.. to ,o u,,o,. ... fn. /.... 1-.... Tl... .l...-..,....,. .. -• «...s 
 down to MTo or U.I0W, Tl..- riv..r i,. Us ..flor.- .0 ,...-. « ..I. ^t^ -> ."-"n- 
 i... boat .t..un., kit it. current is too rapi.l m tV.v/,,. ov.r ; an.l ho 
 a HuporcHW .'urrei.t i. bor,... .low., tl.r.mjrl. th>- ...twurk. 
 
 Th.. n.H«lt iH ol.vi.ms. ,.l..i.r.. ll.at |..v>n.. .....ul.V ....rl-M. ... . .<■ 
 
 thro.ulH ,tr.. n,v..n-.l witl, .i ..rovv.l. ..nV,./,il. wl.il.. .imihir o\.y.i. ... tl... 
 
 ZL r.."»i„ .....V. Si...il.vlv, o,. .. ...U... ........,o to a wa.-.ner 
 
 L,...rat«r.. th.. ...,..-. '^' fnv/il "r- .Lawnl I'. .1.. n tra.l a„..hora,cs 
 
 J. a,.a an. oarri...l .low., l.v .1.. M.va..., A ,,l.....o,.,, ..o.. .... , 1 I, 
 
 1. V ol...rv...... This .I..0.V ai.M.x,,lai..- wl.v IV.u.l .l-... no, t.,..., on 
 
 Idy .,r li.... ,vav..lly t.o..,....s ; li..- wl.,.,.,.v..r tl...rc is any .1.. t.njot the 
 
 oltr«ctio,.s o.. .h..bo„o„. tl....... will aUo l- ..l...n...s .n . ..■ th.-..a,l 
 
 ;i;;i n...si.... ,n.v.....i...ti.at ......i...... .- -.1. .•.■■ - 1 '•';-•'•«■" 
 
 wh.ch is .,..e..sarv .0 .1... (•nrn.a.io.. ..f IV../il. ..■■ so n..n.n^ thread an.l 
 
 m'sh as f. brint^'tl... wl.nl.. al.ov,. .1.. .v.,..i.v.l t..n.,H..ut...v. I ela.n. 
 for this tho,.rv if ..ot al.s.>l..t.. .l,.n.o..st..a.in... a. l-a-t tl... .....r.t ol 
 
 ammnti..,^ rov.,tll know., ia.ts in .■......•.tio.. with .1... u...l aC.o.. 
 
 ''"rmil,asm.k..ow,a,.,».a.si..tl... luimMa n,a<. .1 IVail vavticK 
 with vorv littk colu-sivo ,-.w..r. Tt is vlah. th... that ... sn.all,,..a.. ....-1*. 
 
 or wi.l."anv.hin. Ilk., a iV.... Va-a,.-, i. w-nhl pass away h..n..l..ss y 
 
 seawar.l 'it r,...l,l n..t un.h'r s..c.l. ,.i.-.......s.a......s h.-^-on... suffi<M,-ntly 
 
 densctost..,...u.ni.sow..,,assa,... ..x.-..,,. i-. nl.li..s, wvcl.c spaces, or 
 
 " culs ilo sao. ,, , 
 
 Untovtm.at.lv in .1... St. Law.-.,.... th.-.v a... t..o ,.,a,.y oi all h.sc. 
 Every shoal or l.attu.v aHm.ls s....l. asyl.u.is, int.. wh..l. th.- iraz.l «ra- 
 dually pa.-ks. Kra,u..nts ..i' i.- are tl..,.s, i..t,. th. ...ass aftor.l.n, ..ew 
 cranuici lo.- a.c.u...nlatio.., ,.,..il tl.o «ow ..f tl,. st..ea„. .s .o..h,...l to tu- 
 deeper or n.o... .lir.rt .ha.....!-. U ih.ir tur.. thes.. .l.a.....-.ls « 11 be 
 n,o.st, choke-l at .hei.- bends. ..s,.....ially wh.-.. sl..,als or low ly..., .slands 
 exist 0.. the out.r side of th.. .....v. ol th.' ...m... a,.d .ve.-.v- .t. cen- 
 
 triiupl iinpaH. . 
 
 xNow whon wo na.si.h.r that th.' voh.n.e ..I a r,v..r l.k.- tl... N. Law- 
 rence is not uveat.r i.. wint.'r tha.. i.. sun......r b,.t .ath-r h-s, a,.d that 
 
 at eertain pnints th..... a.v ih.o.ls o,... year. a..d .„.,,.. .1... ...xt, we ..alur- 
 
 ally c..,nel..de that tl.,' Hoods are caused by n.ov tha.. ,.s„:.l ..bstruet.on 
 below, and not by inereas..d vol,,,..,.. The t.„,.Me is. .1., .•elo... h-eal and 
 „.av be re,nov..d with.n.t i,.j..ri....sly aiV.-ti..u other parts .. the r.ver^ 
 
 i,. evert o.,co more to the nat..,e of IVazil. i.. ,.,der to clearly po.nt 
 out the differ........ b..tw..e.. it a,..l s...l'.ee .o.n.,..l ice when ,n n.ot.on 
 
 and floatiu'.: down strea,n. 
 
 Surface i.-e may be seen i.. process of r.rn.ftt...n o.. t.,e ..p... ehann..l. 
 .hooti..,^ out thei^ lances fn„n tloati.... ..udeii. or. n.orc fre,,uently^ pn.- 
 
 jectin^^ its..lf f.-,m. .he sl.o..e ice „..,1.m- the l.^c of sal.ent F'"';- I« ^^f^ 
 ihin Sheets tl.rou.h which the oars of pass.n. boats c,.asl. l.ke br. 1 
 .,1a.. All alon= the open channel fra-.Mnents are broken ..ft by the 
 action ..fwi..d an.l wav. a.,.l float ,lowo u...il stopped by sotne obstacle. 
 I., ,.„ld weath.r these are eith.r ceme-.t.d ..v.ether o., tl.e.r way or 
 ouiekly eonsolidate.l when tl,.-y ar.iv.. at a barrier, and thus, as a rule, 
 •. to,.n,e.l the surface crust ov..r the ,,„.„ channel. A here the water .s 
 still or the crront slu.^.ish the .-peni,,.. el,.s..s s,n..o.hly by the cxtens,.,n 
 of the ice from either si. le. , 1 •» 
 
 - A channel close.l by packin;^ is alw.iys more or less roufxh and ,t 
 would b,. quite possibl.., by critical ..xan.ination, to dete,.m..... the rela- 
 tive force of the currc.t at different places, at the t.me of .ts tak.ug, 
 from the dc-rcc of roughness i.. which it was left. 
 
 There is no evidence t.. show that floating ice is .•ar,-,ed beneath the 
 fi:^cd ice to any i^r.at ...Ktent. except in a strong current Even then 
 the tendency to rise in packin, se..„.s nearly to balance th. downwa,-d 
 movement. Hu,e hun>.nocks arc formed in such places and the ob 
 struetion caused by f.iem is .luc ..hiefly to brokeu sheets caught 
 vertically, or at an an-le with the surface. r.- ■ • 
 
 The character a,..l actio,, of IVazil is totally d.fferent. R.s.ng .n 
 masses from the bott.m.. its buoya.,ey is so small that it floats to a con- 
 siderable distan.e bel.nv the surface ; while so littl." is its cohesion that 
 when the mass becnncs <.ompa..te,l enough to el..vate its upper lace 
 above the water, it falls apart an.l spreads over the suvfae... It often 
 attaches itself t.> floating ice or forn.s a nucleus for a new sheet of ice ; 
 and should sevorc ..old sufficiently ...msolidatc the whole, the surface 
 
 , would be swept beneath the barrier ice, 
 which it was attached. 
 
 the train of the frazil to 
 
the Cn u(^llIm^t»^ll iiulinliK, *liii in winter d«ily trHitnixirt tli«( uiniti to 
 and f'rcim Lathiiic, sliitc tliiit trir/.il «r n\m\\ ice iuuh imly in llio i'»rly 
 part of tlip winter ; nnd that wln'u it cuiim'd to tunm down, tliny know 
 tint till' oil iniirl in clowd «l tin' ii|i|«'r I'nd of ihi- lake. If lliis iH wi, 
 it -liiiwn .itliiT I lull llu' liiuil liinind tii-lnw the liiHciidc rHpidtt renminH 
 flxid to the bittoni an amliot- iof, or, nlml is moro lik.ly. timt b"iiij^ 
 iiir.wi.Ml |py tlio friciion ol' tli.' ovrriyintj ico, it in llirimt iihIiIc and 
 jiininiiil iirlwirn tin' iro mid tlu' tiolt.ini, ovi-r the hattnifH or ithoaU. 
 At unv riOf, it goi-n to |iriivr, linm witlioiit mi o|M'n <'liunn<i. frazil i.< 
 not caniicl down to any )irvat oxtiMii from lakf Ht. l-ouin. Ah a factor 
 in Moiitriiil Hoods, ui.rifon', m wad neck it no further up than the 
 foot of till' Lmliini' nipids. 
 
 Uy koupin;; the cIhiiiihI up, ii Ik in iIhw nipidrt down to the toot of 
 Montreal Istlainl it would r«.eni that thr IVa/.il would be carried pa»t 
 without «erious IimIj:iii( lit , hut iim tlitiv up|K ais 104 yet no means of 
 ettei'ting till- 'ih.i'il. our naiuial r.iiMiiv<e niu-t he to ho prepare the 
 bottom of the river mo a-, to ^ivl■ as fiee a pii-safjie to the frazil ice as we 
 poaxihly can. 
 
 Am will readily hi' iiihiird, 1 ;iiii ^Hoiiiily ol the opinion that the 
 
 disastrous cpriiii; II 1- I'h'Iii wliieh the City of Muiitnal has -.iiffered, 
 
 are caused primarily by the ehokinn of the river diirinu winter, by 
 which the area of the waterway is so itiliiri(l a^ to he iiiiahlc to earry 
 away the iuereasid volume prodiieed by the iinlliim of the snow. Of 
 course this is ajlj-'i-aval •(! by the down tinw nf ire IVom tlii' hikes ub ve. 
 Thi- lattir diffieiilly it has b.eii pioposrd hi prevent by placing ice 
 breakers, or rallier ire anesliiii; jiieM in l-ake St l-oui.-i. iiileiided to 
 keep it back until the barrier hilow ha ■ broken a\v;iy. 
 
 Curiously enough, this coutiivance, tlmujfh one of the oldest known, 
 has of late been received by some with so much eiithiisiasiii, that 
 disputes have arisen as to who had the honor (d' lirst suug.stiii,. it; not 
 auioiej eligilieer.s, however, ll has 1» 11 ll>ed in various hi iielirial ways, 
 chiefly in seenriie,; ;in ir^ bri(l>.'e at some dani;erous spot. 'I'lie hitcst 
 ease nf tie kiml. known to 111. ■, was for the purpose (d' making a road 
 upon whieli to liuiil slniir ;inil I'thrr iniileriai lor the repair ol the Ca- 
 rillon dam ; a pari of vvhii'li hail breii iiinKi mined ami emrieil away 
 the pirvious year. The attempt, wliieli was entirely successful, was 
 madi' iiii.ler the iliirilinii ol .Mr. Stark, superint' ndiiig engineer of the 
 Ottawa Uiver Caiial< 
 
 No doubt such 11 ]iliiii apjiiied to Lake .St. Louis wouhl aiueliorale 
 spring floods at .Mniitreiil it we were sure that it would <iituil no other 
 conseouriires. Uiit there remains a serious (|uestioii : whether in so 
 doing, the ice would not park -o heavily above, ii>^ tip flood the upper 
 country, and the water obtain so great a head as to carry piers and 
 everything e!se beh)re it, ami bring a worse disa.sler upon the city. 
 
 From the t'laeizoing eonsiderations it seems reasonable to eondude 
 that the direction of ;my effertive op ration-; for the prevention of 
 floods, should be in the followini; lines ; 
 
 1st. Slraiiihteiiing the ehaiin<ls . or where this ecnnol be done en- 
 lar"in" them !it their bends, by cutting away the inn r side« 
 
 2nd. ('learing away boulders anil other elevations, 011 th(^ shoals out- 
 side the bends, wherever the thrii>t of the stream tonds to carry ice and 
 frazil into wedge places and euls de sac. Giving the bottom a down- 
 waril gr«de of the stream to give free egress to ico entering from above. 
 3rd. Keuioving ov<'r the whole area of the part of the river aUeeted, 
 all boulders, ledges ami other projectiiais of the bottom. Thorough 
 cutting ;U1 sub eliannel.-, so as to give them a free i(is<-l!arge at the out- 
 let ; and beiiehiiig such shallow .~!oprs along the shoals as in combina- 
 tion with the surface ice aftbid the natural traps in which the Irazil is 
 caught. 
 
 Since writing the above a reeommeiidation of the (lovernment Com. 
 mission on Floods has been partially put into I'fl'eet, namely, an attitinpt 
 to keep open the river channel between Three Kiveis and 8orel, by 
 means of vessels lltled to bruik uji the ice. 
 
 While very dinibtful of its suecess as a means of preventing floods at 
 Montreal, I nevertheless heartily endorse the experiment. \u such a 
 diflicult (juestion the experience gained in an ettort of this kind must 
 greatly help im a solution, and may lead to other discoveries of benefit 
 to the country, which otherwise would remain unknown. 
 
 Montreal, 14th Dec, 1886.