IMAGE EVALUATION 
 TEST TARGET (MT-3) 
 
 // 
 
 O 
 
 y 
 
 ^ 
 
 ^ 
 
 ■sS 
 
 »; 
 
 
 V, 
 
 1.0 
 
 I.I 
 
 III 
 
 1.25 
 
 150 '""^ 
 
 2.5 
 
 1.4 
 
 |||M 
 1= 
 
 1.6 
 
 Photographic 
 
 Sciences 
 Corporation 
 
 iV 
 
 ^^ 
 
 :\ 
 
 \ 
 
 ^>\ ^k\ 
 
 V"^v^ 
 
 "-C,^ 
 
 # 
 
 23 WEST MAIN STREET 
 
 WEBSTER, N.Y. 14580 
 
 (716) 872-4503 
 
CIHM/ICMH 
 
 Microfiche 
 
 Series. 
 
 CIHM/ICMH 
 Collection de 
 microfiches. 
 
 Canadian Institute for Historical Microreproductions / Institut Canadian de microreproductions historiques 
 
 :\ 
 
 ►» 
 
Technical and Bibliographic Notes/Notes techniques et bibliographiques 
 
 The Institute has attempted to obtain the best 
 original copy available for filming. Features of this 
 copy which may be bibliographically unique, 
 which may alter any of the images in the 
 reproduction, or which may significantly change 
 the usual method of filming, are checked below. 
 
 D 
 
 D 
 D 
 
 n 
 a 
 n 
 
 n 
 
 n 
 
 Coloured covers/ 
 Couverture de couleur 
 
 Covers damaged/ 
 Couverture endommagee 
 
 Covers restored a:^d/or laminated/ 
 Couverture restaur^e et/ou pellicul^e 
 
 Cover title missing/ 
 
 Le titre de couverture manque 
 
 Coloured maps/ 
 
 Cartes g^ographiques en couleur 
 
 Coloured ink (i.e. other than blue or black)/ 
 Encre de couleur (i.e. autre que bleue ou noire) 
 
 Coloured plates and/or illustrations/ 
 Planches et/ou illustrations en couleur 
 
 Bound with other material/ 
 Relii avec d'autres documents 
 
 Tight binding may cause shadows or distortion 
 along interior margin/ 
 
 Lareliure serree peut causer de I'ombre ou de la 
 distortion le long da la marge interieure 
 
 Blank leaves added during restoration may 
 appear within the text. Whenever possible, these 
 have been omitted from filming/ 
 II se peut que certaines pages blanches ajout^es 
 lors d'une restauration apparaissent dans la texte, 
 mais, lorsque cela 6tait possible, ces pages n'ont 
 pas iti filmdes. 
 
 Additional comments:/ 
 Commentaires supplementaires- 
 
 L'lnstitut a microfilma le meilleur exemplaire 
 qu'il lui a et6 possible de se procurer. Les details 
 de cet exemplaire qui sont peut-dtre uniques du 
 point de vue bibliographique, qui peuvent modifier 
 une image reproduite, ou qui peuvent exiger une 
 modification dans la m^thode normale de filmage 
 sont indiqu^s ci-dessous. 
 
 T 
 
 r~~| Coloured pages/ 
 
 Pages de couleur 
 
 Pages damaged/ 
 Pages endommag^es 
 
 D 
 E 
 D 
 
 D 
 
 n 
 
 Pages restored and/or laminated/ 
 Pages restaur^es et/ou pellicul^es 
 
 Pages discoloured, stained or foxed/ 
 Pages ddcolorees, tachetdes ou piquees 
 
 Pages detached/ 
 Pages d^tachees 
 
 Showthrough/ 
 Transparence 
 
 Quality of print varies/ 
 Quality indgale de I'impression 
 
 r~n Includes supplementary material/ 
 
 Comprend du materiel supplementaire 
 
 Only edition available/ 
 Seuie Edition disponible 
 
 Pages wholly or partially obscured by errata 
 slips, tissues, etc., have been refilmed to 
 ensure the best possible image/ 
 Les pages totalement ou partiellement 
 obscurcies par un feuillet d'errata, une pelure, 
 etc., cnt it6 fiJm^es d nouveau de 'aeon a 
 obtenir la meilleure image possible. 
 
 T 
 
 P 
 o 
 
 fl 
 
 C 
 b 
 
 ti 
 
 Sl 
 
 o 
 
 SI 
 
 o 
 
 T 
 
 SI 
 
 T 
 \M 
 
 d 
 
 ai 
 b 
 ri 
 rt 
 
 IT 
 
 This Item is filmed at the reductio i ratio checked below/ 
 
 Ce document est filmd au taux de reduction indiqud ci-dessous. 
 
 10X 14X 18X 22X 
 
 26X 
 
 30X 
 
 
 
 
 
 
 
 
 J 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 12X 
 
 16X 
 
 20X 
 
 24X 
 
 28X 
 
 32X 
 
The copy filmed here Itas been reproduced thanks 
 to the generosity of: 
 
 McLennan Library 
 McGIII University 
 Montreal 
 
 L'exemplaire fllmA fut reproduit grftce A la 
 g^nirositi de: 
 
 McLennan Library 
 
 McGill University 
 
 Montreal 
 
 The images appearing here are the best quality 
 possible considering the condition and legibility 
 of the original copy and in keeping with the 
 filming contract specifications. 
 
 Lee images suivantes ont iti reproduites avec le 
 plus grand soin, compte tenu de la condition at 
 de la nettet* de l'exemplaire filmi, et en 
 conformivA avec las conditions du contrat de 
 filmage. 
 
 Original copies in printed paper covers are filmed 
 beginning with the front cover and ending on 
 the last page with a printed or illustrated imprea- 
 sion, or the back cover when appropriate. All 
 other original copies are filmed beginning on the 
 
 rst page with a printed or illustrated impres- 
 sion, and endinfj on the last page with a printed 
 or illustrated impression. 
 
 The last recorded frame on each microfiche 
 shai! contain the symbol —»> (meaning "CON- 
 TINUED"), or the symbol y (meaning "END"), 
 whichever applies. 
 
 Lee exemplaires originaux dont la couverture en 
 papier est imprimte sent filmto en commenpant 
 par le premier plat et en terminant soit par la 
 dernidre page qui comporte une empreinte 
 d'impression ou d'illustration, soit par le second 
 plat, selon ie cas. Tous lee autres exemplaires 
 originaux sont filmte en commen^ant par la 
 premiere page qui comporte une empreinte 
 d'impression ou d'illustration et en terminant par 
 la derniire page qui comporte une telle 
 empreinte. 
 
 Un dee symboles suivants apparaitra sur la 
 derniire image de cheque microfiche, selon le 
 cas: le symbols —»> signifie "A SUIVRE ". le 
 symbols y signifie "FIN". 
 
 Maps, plates, charts, etc., may be filmed at 
 different reduction ratios. Those too large to be 
 entirely included in ore exposure are filmed 
 beginning in the upper left hand corner, left tc 
 right and top to bottom, as many framee as 
 required. The following diagrams illustrate the 
 method: 
 
 Lea cartes, planches, tableaux, etc.. peuvent dtre 
 filmte A dee taux de rMuction diffirents. 
 Lorsque le document est trop grand pour Atre 
 reproduit en un seul clichA, il est filmA d partir 
 da Tangle supArieur gauche, de gauche A droite. 
 et do haut en bas. en prenant ie nombre 
 d'images nicessaire. Lee diagrammes suivants 
 illustrent la mithode. 
 
 1 
 
 2 
 
 3 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
A PAPER 
 
 ON THE 
 
 LATEEAL PEESSURE OF EUMING 
 
 WATER, 
 
 R&AD BEFORE 
 
 Ck 
 
 ♦ !♦ 
 
 mxxwk m%mi\\m 
 
 FOR THE ADV iNCEMENT OF SCIENCE, 
 
 At the Meeting of that body in Montreal in the year 1857, 
 
 BT 
 
 THOS. GUERIN, 
 
 Civil Engineer. 
 
 k 
 
 Montreal : 
 
 PRINTED BY J. STARKE & OO. 
 
 1858. 
 
 \ 
 
a 
 
 T U <? f / I ( 
 
 41k 
 
 a 
 i1 
 i] 
 
 a 
 
 tl 
 n 
 
 B 
 
 e] 
 t( 
 
 s< 
 
 fr 
 
LATERAL PRESSURE OF RUNNING WATER. 
 
 This subject I have selected in order to call to it the 
 attention of Scientific Men, for, as a general principle, 
 it has not as yet been thoroughly developed. A full 
 investigation of it would be a great acquisition to the 
 Science of Hydraulics ; several cities would reap the 
 advantages of it, and among others, Montreal at the 
 present time. 
 
 In all cities which are built on a low flat surface, 
 there exists some difliculty in ascertaining the best 
 mode of their efectual drainage. The outlet for the 
 drainage of a city must be some adjacent stream or 
 River, and if the surface of the town be not sufficiently 
 elevated above the bed of such stream or River, so as 
 to afford the necessary fall to the main sewers, the con- 
 sequence will be inadequate sewage with all its con- 
 comitant evils. 
 
 It is generally thought that to ensure the discharge 
 from the main sewers of a town, it isjiecessary to con- 
 
xv «n +Tint their bottom levels may not be 
 struct them so that tneir dox 
 
 :ruve .J fro. the ^^^^^J^^ 
 the pressure of «ter against any pomt m 
 
 -r^ioKt^sS^^^^^^ 
 snersieorraroithatu.ay 
 
 -"trt'th: SSSLnit isevident that in Wse 
 „f a River or wL running in a W, that principle no 
 iJhXtat that there is a portion of the depth 
 
 counting from this point, *^ Jf '"^^^^.^j^^tion of 
 .. the depth increa-s^^- ^ha^ Je ^Jr^^^ ^^^^.^^ 
 
 this Poi-^* --ll ^^^^f'LTl of 'running water, a. 
 the question of lateral P^'' y„h to discharge 
 
 ri::f^"i"^tr:strea.orKiver 
 
 ^f^^ritfto suhmit the reasoning .hi^ 
 ■J^ the conclusions^I^e^rnv^ at e.^^^^^^ 
 myself that, as a general subject, x ud.v« 
 
vanced its investigation, and especially ^so far as the 
 River St. Lawrence is concerned at Montreal. I believe 
 I have given a solution to this intricate question in the 
 present paper. 
 
 As the lateral pressure of water running in pipes, is 
 included in the heading of this paper, I will, therefurj, 
 first devote some attention to this part of the subject 
 and for the purpose thereof, I will mention the following 
 experiment which I have witnessed. 
 
 At the end of 6000_feet of a conduit which had been 
 10 inches in diameter and which communicated with a 
 reservoir, there was attached a branch pipe of .0()25 
 feet diameter, the last portion of which for a distance 
 of 20 feet was laid horizontally, and to its end was 
 attached a cock, a hole of one eighth inch diameter was 
 made in the horizontal part, and it was found that 
 while the cock was opened no water had issued from the 
 hole. 
 
 The height of the E servoir above the horizontal 
 part was 42 feet, and at first sight, therefore, it did ap- 
 pear a little surprising, that under so great a head no 
 water had issued from the hole referred to, and con- 
 sequently no lateral pressure existed, while the cock 
 remained opened. What, therefore, is the real state of 
 things 1 
 
 With the data already given, and supposing that there 
 had been no other discharge nor leakage through the 
 conduit, we shall find that the discharge through the 
 
6 
 
 branch will be .024 cubic feet per second ; if now we 
 compute tlie friction on the 90 feet of branch we will 
 find it to be equivalent to a head of 38.6 feet, thus leav- 
 ing only 3.4 feet of efifective head to force out the water, 
 that is to say, of the entire 42 feet of head of the re- 
 servoir, above the orifice of efflux, there had been only 
 3.4 feet efficient, and even this quantity is obtained on 
 a supposition of there having been no leakage or that 
 there had been no water drawn off elsewhere from the 
 conduit while the flow was passing Jhrough the branch. 
 This head of 3.4 feet must cause a pressure on the 
 water in the branch of 1.5 lbs. per square inch, and 
 whereas no water issues through the hole alluded to, it 
 would appear that in the instance jus^; cited there was 
 no lateral pressure, but that the whole force or pressure 
 of 1.5 lbs. per square inch, must have been exerted in 
 the direction of the pipe. 
 
 Will the water which is running through pipes exert 
 a lateral pressure in any instance, and if it does, what 
 is the amount of such pressure 'i 
 
 Before answering these questions I beg to remark 
 that although the measurements and calculations in the 
 above instance have been made with the greatest care, 
 yet it is not my intention to draw any general conclu- 
 sions therefrom, being well aware of the danger that 
 exists in drawing conclusions from experiments which 
 are roughly made. The'reader will permit me, however, 
 to submit the following explanation to which I have 
 
tireiy original as far as I am aware of ;— 
 
 >n 
 
 Let a horizontal pipe A B be fitted to a reservoir 
 wh,oh.skept full of water, let X be a cock who^S 
 equals the section of the pipe, let C N, D 0, B p"^ 
 tubes inserted in the pipe, and let us sum,e fo^ » 
 moment that the« is no contmction at A, bT^Ie wlr 
 running through the pipe. ^ "***" 
 
 When the cock is closed, the wbnlo«f*i.„ • ■, 
 faceof the pipe will e.,.rL^ :l^..^lZXZ 
 must nse m the tubes to the same level as the « 
 but when X IS opened, the water rushing out afl^ h 
 a velocity due to the head A M will Lmedial a^^ 
 qmre the direction A B, and by its impulse wU rut 
 along the p.pe without being turned into Lj otCdi^ 
 tion, the water in the tubes coming m contoctet^' 
 moment with that in the pipe will !e borrat " ^ 
 level in the tubes mnst soon fall and be redu^;! to 
 nothing hence while the section at A and B 1 the 
 same^he horizontal pipe can experience no Tjitl 
 
8 
 
 If the cock be only partiiilly opened, the phenomcici 
 must chancre ; the water will pass through the orifice 
 with a velocity due to the hcoiX A M, but the head due 
 to the velocity at C or D must be less, for the reason 
 that the sections there are greater ; let V be the velocity 
 at or D, and 7, will bo the head employed to produce 
 it, {g denoting the force of gravity or 32.18 ft.) and 
 whereas it still acts in the direction A B, it can pro- 
 duce no lateral pressure. 
 
 The quantity S is less than A M, it is that 
 portion of A M which produces the velocity V 
 along the pipe A B, but as the water in the pipe ex- 
 periences the force of the whole head A M the re- 
 maining portion A U=^V, would appear to be the head 
 indicating the pressure on the pipe, and undw these 
 circumstances, if there had been no friction, the water 
 rise in the tubes to that height, or if we take M E 
 equal to !g, A E will represent the height to which the 
 fluid will rise in the tubes. Now it is well known that 
 friction in pipes destroys a great portion of the head, 
 and it is also well known, that this friction is directly 
 proportional to the length, that is, it increases from 
 nothing at A to its greatest limit at B ; let us call F 
 the friction at B and make v'' a" equal to F and join 
 E a", the friction at C & D will then be represented 
 by v a kv' a', hence we conclude that the column 
 C N which measures the pressure when in a state of 
 rest, will, when motion begins, first fall the quantity N v 
 
9 
 
 (-■«)and secondly V a; this last part of the head 
 being deEtroyed by the friction of the pipe from 4 to 
 The pressure at C will then>fo« be represented by aC 
 and will bo equal to A M-^-friction at 0. This last 
 teiTO otjnction ai C, will be equfl to .00071 \f wher« 
 L IS the length, Q the discharge, and D the diameter of 
 the pipe, but m the present instance, these quantities 
 are to be estimated at C. 
 
 If the pipe instead of being horizontal is inclined 
 our course of reasoning will be similar to the fore- 
 going-when the orifice is closed, the water will rise in 
 the tubes to the same level as in the reservoir, but when 
 motion begins the level in the tubes will undergo the 
 same d,n.,u„tion3 as in the case of horizontal pipes, 
 and their summit will only attain the line E a * 
 
 If the pipe is bent and not a shuightline, the ex- 
 pressm for pressure must be the same, recollecting 
 that Lw the real length along Ae sinuosities of the 
 pipe, lience we conclude in general terms, that if H 
 represent the height of the reservoir above any point of 
 a pipe whether curved or straight, that the pressure on 
 ais point will be H--_.00071 \f where V denotes 
 the velocity at that point, and .00071 \fis the height 
 representing the loss frem friction at the sa^e po£ 
 then as H-.00071 \f is the efficient head, we havj 
 the pressure a,lways equal to the efficient head (not the 
 ordinary head) minus the height due to the velocity 
 Having treated of the lateral pressure of water in 
 
 \l 
 
10 
 
 pipes, I come now to the pressure of water running in 
 a bed, the subject which this paper principally aims at. 
 I will suppose A B C D to be a section of ^he bed of 
 a River, the depth of water there being H B, and I 
 will suppose that at the depth x n, (=ll n') an 
 opening is made ; it is required from thence to deter- 
 
 ■ 
 
 mine the quantity of water that will flow out at n, 
 through the small canal n S into the basin Z. The 
 velocity of the River being given. 
 
 Suppose* that the motion of the water in the bed of 
 the stream is aiTested for a moment, then it is evident 
 that the flow through n would be that due to the head 
 X w, but as soon as motion commences this phenomena 
 no longer holds, a portion of the head on n, will be 
 destroyed by so much as causes the velocity in the bed ; 
 let us denote this by H m, that is, let the head H m 
 be that which is due to the velocity in the bed or I? 
 where V denotes the velocity, and g the force of gravity 
 (32.18 ft.), then it is evident th? fc x n will be dimin- 
 ished by H m. Now besides the force which H m 
 exerts, there is another force acting in the direction of 
 

 n 
 
 moment. In all steams, however LJ! 7 
 
 a uniWty of motion, k^rTZL^r^^ZZ^ 
 t.on. even m canals of the sm^thest and m st „^£: 
 bottoms, where one would suppose the friction woulZ 
 exceedingly small, hence it follows, that the forZsS 
 mvariably destroyed in all streams by somellltt 
 sistance, such as friction, &c. "^^ 
 
 Now if V denote the velocity in the bed of the stream 
 . would be the head, which would be sufficirntl' 
 generate thjs velocity if there had been no such thL^ 
 •t fncnon but as ./ S also assists in its generatiln 
 aMough be„,s destroyed by friction, we ha^ S^' 
 
 :*city V^ ;:;'" ■--■-P'oy-l togenen^te : 
 velocity V. 1 lus force is employed in the direction nf 
 
 ished by this quantity, in order to determine the head 
 which forces the water through this of^ning The S 
 on the opomng will therefore be H n-7-y "enead 
 
12 
 
 ■ 
 
 From this it follows, that at least the portion of H % 
 Which IS equal to g + gr S will be employed in the direc- 
 tion of the current, it will cause no pressure on the banks, 
 aad It will therefore denote the point below the surface 
 of a stream at which the lateral pressure commences. 
 
 To apply this theorem to the St. Lawrence at Mon- 
 acal, the reader will perceive that owing to St. Helen's 
 Island and Isle Ronde, which are opposite to this city, 
 the bed of the River is divided into two parts, by far 
 the greater portion flows between the Islands referred to 
 and the city, and is called the current St. Mary, a name 
 which I will adopt in this paper. 
 
 The length of the current St. Maiy is about 5,000 
 feet, Its width is about 3000 feet, its Hydraulic depth in 
 Summer is 35 feet (estimated), and the difference of level 
 in Summer between the head and foot of the current St. 
 Mary or rather between those portions of the River St 
 Lawrence, above and below those Islands referred to, is 
 2i feet. From these data we can easily ascertain the 
 ^lue of the expression V, + g S, it will be 2.36 feet 
 Hence we conclude, that a stream or sewer can be dis- 
 charged m Summer into the current St. Mary, at a depth 
 of 2 feet 4 inches, below the surface of the River with- 
 out meeting any impediment. 
 
 In Winter the St. Lawrence rises so high as to cause a 
 hydraulic mean depth in the cmTent St Mary of about 52 
 feet ; there will be a difl-erence of level between the head 
 and foot of the current in Winter generally of 8 feet. 
 
13 
 
 ^*- This is the LihZrVi + « «'= "-10 
 
 of this depth that the ,:i;'l^' '^^ t«-ination 
 an opening «« ^^, in fte h T''/°"""^°'=''«- ^ 
 l-rtion of this depth no Z^'o^:;}^' f «'- ."^^ any 
 tf a stream or sewer diseharS in "!'"«'' "'' ""^ 
 Mary at any portion of this IZl . ', '"^'«"' S'- 
 no impediment from the water of Lp'''"'''' '"^*^'* 
 
 Having thus far deveW i^ ^?''- 
 pressure of running water Iw. u P'"""" "^ ^^f^ral 
 oluding this paperf tTat V ^ ^ '"«Sest, befoi^ con- 
 
 iead than g's i'd sdyTf *** ^™^ 
 l-e said by theory at pwlt • f'""' ''" ^'^^ "an 
 destroyed for the reason haH *'' "*'^'' ^ » is 
 ^^ velocity of the ste^m ''^^ ;^. "^ "f"""- « 
 greater portion than g S we n,,^/ T "^"''^^^ * 
 Must be diminished by a JIT ''°°''"'^'' ^'''Hn 
 and consequently theiirarXT7 J'^" '' + ^ « 
 nre commences must be still f.f ? * '*'*'^' P^^s- 
 of the stream than J + g g ^'*"'^«'- ^^°^ t^e surface 
 
 --/Set:tiLtt:rt\"-«'^^-e- 
 
 Paper has not at pST * '^' '"'''' »f this 
 but it is to be hoz^riVt '^Tf ^""-""Pli^ting 
 give the subject aftought °' '^'^ '°^^ -'" ^'^t 
 
 THOMAS GITERIN. 
 
OJ 
 
 IE 
 
 be 
 8: 
 thi 
 no 
 
 sta 
 
 its 
 
 bac 
 
 ha^ 
 
 the 
 
 alei 
 
 rive 
 
 sew 
 
 the 
 
 aboi 
 
 Mar 
 
 Ti 
 
 wate 
 
 appei 
 
 at th 
 
 in ti 
 
COROLLARY. 
 
 r 
 
 -to a„J other pit ontt ritef'^' ""'•''*/'«''' *- 
 
 8 feet higher i„ the winteTa^dTtstoeut""^" ""'"" 
 the shore being retarded hi ft I ^ ^'^•''"*°* ^ 
 nothin,. ; h.„ce^he water it"^ tt "''' '' "'™" 
 
 3tandator„earthele?of th If"" T' ^°"''» 
 A co,,r.« r 1. .^^ ^^ t^e water m the river 
 
 A sewer discharging into the current St IVl" 
 Its foot, will have th- advnnfon. T! ^- ^^^^' ^^ar 
 
 backpressure ofLtSlJ^'^^f''^^ '^'^ 
 have already shewn and II^ . '«'' ™*^''' *» I 
 
 the harbour't wnUe "L ^jT^"^/'* ^ «-er at 
 alent f„ the difference of t™i f f "'' ^''''"^^ ^1°'^- 
 river in the harTu^^^d t ,'^^0 T T' °^ *« 
 sewer, which difference 1 t „ "'^'"^ "^ t^"* 
 
 the current, will ZlTfTl " °''I ^'^ '°°' ^^ 
 about 17 feet of ad aZrin£or !?!*'" ^'" "^^ 
 Mary in this case ** """«»' St. 
 
 waSiatrss;^™r- ?'^^*^-^^- 
 
 appearfrom the fact twT. f f ""''^JagaBay.&c., will 
 « the sewer .iK^afhitr:! ^.'^^^^^^ -*«' 
 
16 
 
 Now if we suppose that the water of the river at the 
 locality of the proposed sewer at the current St. Mary 
 is two feet higher than at Hochelaga Bay, &c., it would 
 appear from what I have already shewn that the level of 
 the water in a sewer at the current St. Mary will stand 
 almost nine feet lower than in a sewer at Hochelaga 
 Bay, &c. Hence there will be about nine feet in favor 
 of the current St. Mary, when it is high water in the 
 St. Lawrence, this being the stage of the river for which 
 these calculations have been made, because at any other 
 stage there can be no difficulty or impediment to the 
 discharge of a sewer in any locality. 
 
 Other important advantages which can be urged in 
 favor of the current St. Mary when compared to Hoch- 
 elaga Bay, are the increased length and increased de^jth 
 of excavation which the latter locality requires. 
 
 From levels which I had occasion to take in that vi- 
 cinity some time ago, it appears that there is a regular 
 ascending grade from the Victoria Road onwards to 
 Hochelaga. This will appear evident, even to a casual 
 observer, from the fact that the stream which crosses 
 the Victoria Road near the Queen's Square comes from 
 the direction of Hochelaga, so that there can be no 
 doubt of the increased depth of excavation in that direc- 
 tion. Hence, I conclude that a main sewer from the 
 City, entering the river near the foot of the current, will 
 be much more efficient and much less expensive than 
 one entering Hochelaga Bay, or any point below it.