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Las diagrammas suivants illustrant la mOthode. 1 2 3 1 2 3 4 5 6 MKROCOrV nsOUITION IBT CHART (ANSI and ISO TEST CHART No 2) ^ ^iPPUEDjvHGEln ^^m '653 Eost Main Street Kb ,!f^?""- Ne* York 14609 u>u ■■^ ("6) ♦82-0300 -Phone "^ ^^ (716) 2M-5989 - Fo. i \c^. 1 ^.> ^ ^ ^ TIDE LEVELS Si AND ^ > DATUM PLANES IN EASTERN CANADA From determinations by the Tidal and Current Survey up to the year 1917. VV. Bku. Dawson, M.A., D.Sc., M.lNsr.C.E., F.R.SC., Superintendent or Tidm. Survbvk. 9abli r*^ TIDE LEVELS AKD DATUM PLANES IN EASTERN CANADA From determinations by the Tidal and Current Survey up to the year 1917. W. Bell Dawson, M.A.. D.Sc., M.Inst.C.K., F.R >.C., SlPERINTEXDENT OF TiDAL SURVEYS. 9ublitt\titt 0ttatM, CanabA. 28186—1 OTTAWA J. DE LABROQUERIE TACHfe PRINTER TO THE KING'S MOST EXCELLENT MAJESTY D«ac. 1985 i.«>( u.rrihs, r'>l< MMIiH IIIIL Ll.tl.l.a Mm l.l\ t.V, V« '"(• I'rim ipul •iHliiin .. «r. LAM mi;m I «wivt gi Klu ;- ( 'liuiiiplain I up i\ lit HihIk'. • ■riinclinix I'l.int I'liiiiiii >t. NhImiIiik »T. LAH NKM K IMTI rit(niiii\ I'liirii ' 'up 'X i V iirif HivhTf « l-lM'nuniaiii.i J'-n'riiy iKlftn,. Father I'ninl. - I'rin. i|>nl stntiim Mntuni' (■rHHilM M/>rtiinH I'oint ili« Mi.iiiH 'iiix- <'lllll Stc. Anni' i|i-B Monta I m ir (ir ST. i.AWHrM r.— N.irtli (.Imri:- Scvrn Nl.iiwls ... Kllid lm> Aniinmii Miniinn Kitkiriio I'liint Natuahkwun liiirlxiur Hnrri.'ucton Himm Kii|rf'ninr<' I'ort SuuncliTii, Nfl'rt >IILE IXLK KTHAIT:— Furttiiu '«!».— I'riniipul DtBtiim. Chati'HU Imy 1 IIALKI'H BAY:- I'lirt Dunii'l Tiifipfhiuc. < 'urii'liin \\ DiillinUHio. ''uinplic'lltc Hittliuriit rurji«|u«'t MlltAMKIII BAY AND BOLTllW AHO:— Lowrr NcKUHC . , '•ilk Tiiint 1.1 11 IN IX IN IN IN l» ;>u :>i ■i\ Si 23 ■:% 25 :a 27 2N :'N .11 »l ;i2 :« 33 3A 37 37 3N 38 3N 39 30 40 42 42 42 43 43 44 4.1 45 47 48 MIHi Mlw >N^t If <'lll»lll:.ni \ H .Minihii. hi n. I'i'ini ^Hpiii Ml* liiliu' ti. SIm.1i,.. I,.„ • 'iipi' Tiiriiii'iitin. r..rl lli.njin ( iirhton IimmI) I'lirt KIkii) ill Hull Virli. Suriiiii.r.iilf, IM.;| I'ichhi. Ki'tiri'iiii' ..tiid.in < hiirliillituiin - I'riiii ipiil niiiiiiin. I ii. Allxrtjm «;) Mulpi'iiui. . m lluxtirii M Si. I'l'tir* ImrliiHir . . (j,n <'a»<)T ktraii ■"^l. I'aiU iila'iil. rriiiripul nialinn tW I'lrt uii« llnMi|ui «, Nll'il HO ■St. .\nn hurhniir 09 .Sy,ln..y, \.S go //a/i/fljr.— I'rinripiil Kt.itiiin . 70 tOI TIIKIIN NOVA XI ini\:- Shi'lliurniv 74 Ip si ■AY or riNuv. TpptT part: — Hiiprwi'll caiw; in lalili' only SJ Moncton , , §5 l*arrHl)on» pii-r gg Wiml.sor, \ ..•• gy ('uiiilii'rianil l.a>.'> f)g Haic Virti', at I'l.iniHh 92 ( 'olicl <'iirr«iit«, iiuk li valiiulilr infiirnwiticin \inn Imtii olitiiincil rcKitnlir tide li'V<-l^, ami ii niiiiihi-r <>f litncli- iiinrkN huvc Ix-cn I'Kttililinlu'tl at the vaiimirt tiiliil >tati«t. Thi»* Hurvi-y, wliirh i* iiiuIit the Ministry of Miiniu' niul in now li lirniirli of tin' Nuvul SiTvici', \m> for its priiiiarv oliji'ct til) (li'tf'rtnitiatioii of ilic tirni'-rrlatioiiH of tli<> I idi', mihI \Ur tiir.i of liilal I'urr' ' , for thf iiiforinatioti of iiiariiicr?'. Tlir (totriiiiiiialioii of IrvrN Ik ihu" ■\v.y i-ollatcral to thr ol)jc('t wliicli the ili'partni*'iit luii in view , altlioiiKli it i"* >i<' ' / within crrtain limit?': lHM'iiU''f at the primipal titlal ■■t;ltion^, it i- i>M'ntiiil to wniintuiii ii unifi :>i iliituni level for tiic reduiiion of ilic oit^^crvutionx. It 1^ highly (leMirtihlo J it thi.^ ^hii not taken more eio^ely than the uear«'! maintain truly acruruti- IfvelM Imt'od on a limit of ai-ruraey ir> the individual ohMervntionM of 01 of u foot in hi'ight. It was thuH evident that tho tidal ohnervations would lie greatly enhanced in value and much information of importance to enKiiw rs woidd be i>ecured, by obtaining reliable levels and by establishing Bencji-marks at all tidal stitioni^ at which registering instruments were placed, even for a few months. The adi»t years was commenced; as will be seen from the following extract from a publication l)y the Superintendent, issued in litOH: " Eventually as the observations are continued, the value of Mean Se:i level, extreme tide levels, and other factors of importance, are determined v.iih 6 reference to the loeal Bench-mark. Although there h a. yet no Rcneral sv.te.n of lev-el8 m Canada, these results are of service locally in the meantime; and thev also furnish a basis for any more extended geodetic levelling which mav be undertaken.' This foresight is now bearing fruit, as the determinations of Mean .Sea level which arc now available at our principal harbours, are being utilized as a basis by the Public Works department for their extended levels, and bv th.- Interior department for jirecise levels in Eastern Canada as well as in British Columbia. For the extensive levels in Prince Edward island, which are being carried along its railway .system by the dep.irtment of Government Haihvavs a basis was afforded by the determination of Mean Sea level at Charlottetown' obtained during the last rive j-ears. Accuracy of Mean Sea /nW.-There is a slight variation in the value of Mean bea level from year to year, which is umloubtedly actual, and not due to any want of accuracy in the observations. A comparison between Halifax and New \ork, on the open coast of the Atlantic, shows an evident correspondence in the variatum at the two places in the sam<- years of the series. The out- standing uncertainty in the value, as determine.l at Halifax from a limited series of years, does not probably exceed 0.013 of a foot, judging by a comparison with a twenty-year average at New York. Such an imcertainty is much le.ss than th(> i)rot)able error on even 100 miles of precise levelling; and it therefor ndicates that the levels them.selves should - be checked by Mean Sea level deu uninations at the ti.lal stations which the Ime^ of levels may connect. This method is adopted in the levelling .sy.stems of India and the United States; .-my accumulate.l error in long land lines bein.^ eliminated at the shore stations where the elevation of Mean Sea level i- ucepted as absolute, if rvations, are some means of obtaining correct time which is often the chief difficulty, and some plane of reference for height. As regards height and levels, a Bench-mark is established for reference and its elevation taken as 100.00 feet. A tide scale is placed with its zero well below the lowest po.ssible tides, so tiiat the registering tide gauge when set to correspond with it, will be sure to record all low waters. The elevation of the zero of this scale is accurately known with reference to the Bench-mark; but it is to be specially emphasized that its zero does not represent any tide level, as these are all unknown at the outset. The scale may be liable to settlement, or it may be carried away and replaced in the course of years. The only essential is that the elevation of the zero should at all times be known without uncertainty. Such open scales can be used at the permanent stations on the Pacific coast, and also at all summer stations; but in Eastern Canada a sight gauge or floating scale has to be used, within the shelter of the tide house wliich protects the registering instrument. It is essentially a graduated rod standing on a float which rises and falls in a -fcond vertical tide pipe, in accordance with the tide. Where the range of the tide is too great to use a vertical rod, a metal tape passing over a pulley is substituted. The true elevation of the zero of this sight gauge is determined from its total length measured from the line of flotation on the float, and the elevation of the fixed gnomon or index point used in reading it. A description of the two types of sight gauge and the various kinds of metal tapes that have been tried, might be interesting; but it will suffice to say that by means of instrumental levels and measurements taken every year, to check any variation through settlement or other causes, the elevation of its 8 zero is at all ti.uos kn.mn within 0.01 or 0.02 of a foot. In ease of a winter accident, the measurements made next season miy have to be carried back to the date of the accident ; but if any un.v-rtainty >till remain.^ the observations themselves have to be thrown out as valueless, at least for the .letermination of Mean hea level; though time results may hold roo,!. The setting of the registering instrument is kept in a.coril with the sight gauge, and any .hfTerence between tiiem is ascertained by comparative readings taken smniltanenusly; just as the time- errors are ascertained bv comparisons with the true tnn.-. By a system of averaging these comparisons, the true relation of th.. zero of the diagram on the r.vording instrument to the zero of the sight gauge IS ascertained. From this in turn, the true elevation of the zero line of each .liagram relatively to the Bencii-mark is defmitelv known It is of course desirable to maintain thee relations as constant as possible for conveni- ence; but so long as the observer takes the comparisons a. directerl, any change IS at once evident; and the reductions are controlled by the headquarters staff and by the levels taken at the annual insjiection of the tide station. Datum kreh.-Thi' reference level to be first determined, and required for working purposes, is the Low-water .latum, based upon low water at Spring tides, as will be explaine.l. This can usually be determined after a few months or from the first year of observations. The Low-water datum then becomes known as a reading on th<- face of the tide s.vale, and as an elevation wth reference to the Bench-mark. This enables the datum to be ruled as a line across the face of each diagram obtained by th.> ivcording instrument. In domg so anv differen.T with the tid.. scale or the sight gauge as shown bv the comparison.s, is allowed for. We now have on our series of diagrams, a datum line at a constant elevation throughout, from which all levels of high and low wai, r or extreme tides can be measured, and brought into relation with the Bench-mark if desired If we are dealing with a summer station, the tide scale has now serv(>d its purpose It is evident that the setting of this scale was purely technical, and the elevation of its zero had no significance except for office reductions. We do not therefore publLsh the elevations of tide scales or sight gauges as a rule; as they might be misunderstood to represent some tide level or datum, which is not the case The (h'termination of Mean Sea level can now be made l is its great convi'niencc to the marii'.ir, in showing the least amount of water availal)le in bays and channel-ways under the influence of the tide. It is therefore almost universally used as a chart datum; and by using the same datum as the zero level in tide tables, the extra depth due to the rise of the tide is made evident. The resison for adopting a Low-water datum at all, makes it desirable that it should rei)resent the lowest level to which the tide usually falls. As it happened that the tides were first investigated on the coasts of Europe and in the North Atlantic, it was supposed that tlieir main variation in range was from springs to neaps with the moon's phases; as this is the dominant variation in that region, where the lowest usual level is at spring tides. The Low-water datum came there- fore to l)e defined as " Low Water at ordinary Sjiring tides;" the term onlinanj l)robably indicating astronomical tides undisturl)cd by storms. We thus start with a definition which is quite inapplical)le to the world generally. The reason of this is that the variation in range from sjirings to neaps is only one out of the three variati(ms that occur from astronomical causes. The other two are variation with tlie moon's distance, and inequality in the two tides of the day which is in accord witli the moon's declination. In some regions, as in the Bay of Fundy, the variation in the range of the tide with the moon's distance from perigee to apogee is distinctly greater than the variation from springs to neaps. Of all the variations from the true average range of the tide, the greatest that occurs is due to diurnal inequality in regions where this feature is the dominant one. It also happens that the average level of high water may remain nearly constant, leaving i)ractically the whole of tlie inequality to affect the low-water level. This occurs both in Nordiumberland strait and the Strait of Georgia, the two regions in Canada in wliich this iney other inequalities. The spring range is 13 feet.) (2) Difference in the level of low water with the moon's distance when perigee and apogee fall at the springs; at the head of the Bay of Fundy in Minas 10 Basin, 5 feet. (Low water at the two spriiiR tides of tii .Kjnth may differ by this amount in several successive months. AveraKe spring range, 45 feet.) (3) Difference in the level of low water on the two tides of the day. At Sand Heads in the Strait of Georgia, 8 feet. At Charlottetown in Xorthiimher- land strait, 3J feet. (This difference occurs whenever tiie moon is in high declina- tion, north or south of the equator. It is accentuated when the sun is also in high declination at the solstices, when the extreme tides of the year occur.) To take the average level between these extremes as a Low-water datum for tides of the second and third types, would not be more unreasonable than to take the average level between springs and neaps for the first type. In all three cases, many of the tides would fall below such a datum, and often to the extent of several feet. A datum for chart purposes which is thus too high, is misleading to the navigator, as he would so often find less water than the chart indicated; and if adopted as the zero level for tide tables, there would be too many low waters with negative values. It is therefore only for the tides of the first type, and in regions where the other inequalities are small enough to be negligible, that the average level of low water at both the spring tides of the month can reasonably be taken as datum. This is the limitation of the original definition regarding low water at ordinary spring tides. For the second type of tide, it is necessary to tah.e the average level of the lower of the two spring tides of the month; and in extreme cases, where the semi-monthly inequality amounts to several feet, the average should include the low waters at perigee springs onlj-. For the third type of tide, it is best to take the average of the lowest low water in each .ronth of the year, irrespective of the cause or combination of causes that make it the lowest. This method was adopted by the Public Works engineers in the early days on the Pacific coast, in determining a datum for dredging. With such a datum, the tides in the vincity of the solstices are the only ones likely to fall below it. A datum determined In- these methods will be satisfactory in being sufficiently low for the requirements of charts and tide tables and for the dredging of chaimels; and it will be found to accord well with the practice of hydrographic surveyors. But the practical difficulty is that the limitation to one tide a month is too meagre a basis for a good average, except perhajjs at principal tidal stations where observations for a year or more are available. Even where springs and neaps are the oi ly marked feature, there is usually enough inequality between the two tides of the month to make it desirable that the datum should correspond with the lower of the two. At summer stations especially, where only four or five month's tidal record is obtained, the limitation to one low water in the month would be too great a restriction, especially if any storm tides have to be omitted as untrustworthy. It is therefore better to take the average level of the lowest low water at each spring tide during the observations, and to allow u margin below this for the other variations. This level is termed " Average level of Low Water at Spring tides," which is used consistently with this meaning throughout these tide levels in regions where springs and neaps are dominant. The wav will 11 l)p fxpliiiueil later by which a suitable margin, between thin level and the Low- water datum, is arrived at. Tor high water, the average level of the highest high water at each Spriiip tide is termed similarly " Average level of High Water at Spring tides," and tiie height of this level above the datum is the " Spring Rise," which affords tiie best meanr. of comparing the amount of tide at different localitios, or the increji-e in height with its progress. In determining a Low-water datum for secondary stations on the Pacific coast, where the tides are of the declination type, a special average level for low water is used to bring the local datum into direct correlation with the principal station. The average is taken from simultaneous ol)servations for the same series of months. It was thus only at the principal stations, where a long tidal record is available, that a primary determination of the Low-water datum was necessary. This methotl enables a consistent datum level to be carried throughout a region where the tide is of the declination type and the variation in the level of low water is very great ; making the series of observations avail- able at a secondary station too short for an independent determination. An average level for high water is also obtained; and l)oth a low and high water average level being thus correlated with the principal station, a comparison of the difference of level between them affords a ratio with the rise at the principal station; and this enables the height of any tide at the secondary station to be found from the rise above datum at the principal station as given in the tide tables. The ratio is readily applied when once it is determined. In Eastern Canada, the only principal tide stations at which a Low-water datum was found already referred to a Bench-mark during the Admiralty surveys, were Halifax and (Juebec. At St. John, X.B., a tlatum had also been estabUshed, but the Bench-mark was destroyed in the great fire of 1877. These two available datums were adopted from the outset; and wherever there was opportunity to make comparison with an Admiralty datum in any of the regions where summer stations were established, the endeavour was made to keep new datums consistent with it; as well as to maintain harmony between the datum at the principal stations and local datums in the same region. From such comparisons in regions where springs and neaps are dominant, and from datums established by this Survey which had proved to be satisfactory for tide table purposes, the margin of allowance was arrived at, l)e(w(en the standard level of Average Low Water as already defined, and the Low-water datum. This margin runs from about 0..50 foot to 1.50 feet, according to the range of the tide. This may be considered as an allowance for the variaticjn between the two spring tides of the month, or for the diurnal inequality, as these do not usually occur together; making it seldom that the spring tides fall below datum. For both variations to concide, the moon's perigee must fall at ♦' springs, and its ma.ximum dechnaticm must occur near the same date; u with this co-incidence there will be negative values in the tide tables. We have thus explained in some detail the method of dealing with tides in which the springs and neaps are the dominant feature, and the other variations although relatively small cannot be ignored, as the tides of Eastern Canada are largely of this type. It may also be said in general, that the datum level arrived at by this method, and by the others described, is found to be in good 12 accord with the Adminilty pnicticp in chart xurvrys. Wc will iilso give ho ••xunipics to sh(>w the roliition ot the dututii to ol)sprvcd low wutcr in diffon rogions. When the diituni is decided upon, it can uIwayM he defined with referei to a lociil Beneh-iniuk, or Mean Sea level where this is known. Range of the tiilr. — The truest ( . auparison of tides with each other is means of the range from low water to hiRh water, under any given conditio This is the actual amplitude of the tidal undulation, uny the Public Works dejiurfment, runs primarily from Halifax to Father Poi and determinutions of Mean Sea level at both these principal stations have h( made available l)y tiie Tidal Survey. This line of l<>vels, running across ( three provinces of Nova Scotia, New Brunswick and ea^stern Quebec, is tl checked at both ends. From this north and south line. 480 miles in h".,; as a base, the mean level of the sea can be carried westward to the upper La\VTence, wher(> it connects ^.vith the New York system at the head of Lti C'hamplain and in the region of the Great Lakes. From this base line of levels, branch lines have been carried eastward the CJeodetic survey to jjoints on the east coa.st of New Brunswick, along Chah bay to Ga.spe, and all along the south shore of the St. Lawrence estuary. '1 elevations of the various local Bench-marks alre.-uly established by the Ti( Survey, are therefore given wherever the Geodesic survey has now made conn tion witii them. In the coast region of the Maritime provinces, the Dominion Observatc in the Interior department has carried levels through southern New Brunswi and Nova Scotia from the frontier of Maine to the Gut of C.inso. A dati for this line was obtained by the connection of its western end with Mean f" level at New York by a land line nearly .oOO miles in length, nmning throu the intermediate States. Another line runs across this, from Halifax to Monct( and a third line follow> the Nova Scotia shore from Halifax to Yarmoutii, which a check is tiiveained at the Yarmouth end by a deterniinati(m of Me Sea level there, based on 07ie complete year of ol)servation by this Surv( Several other lines of levels run by the Dominion Observatory, li;- further inlar and do not connect the tidal stations on the coast witli each other. In Prince Edward island, an extended series of levels is being carried alo the railway lines by the (iovernment Railways (lei)artment. These lev are based o,i j\Tean Sea level as deterniiued ;i 'harlottetown from five comph years of tidal observation there. On the long stretcli of c()ast, ()4.j miles in length, from the Saguenay to Be Isle strait, there are no continuous levels: although tide levels are now knoi locally at a series of stations in this region. There is also a well-determin value for Mean Sea level already available at the far eastern end, at Forte bay in Belle isle strait. I give Honu' in (liffomit h reference other is liy <'i)n(liti()n><. lent of liny )r this very mrrieil onf thor Point; < have i)een across the )ec, i.s thus i in h',,;ti), ? upper St. ad of Lake istward by ing Chiileur nary. The the Ti(hil ide connec- il>sorvatory Brunswick A datum Mean Sea iiK thruut;!) ) Monet on; mouth, for n of Mean lis Survey, lier inhind, rried ah)ng hose levels ■e complete !iy to Belle low known ;letermin( (1 at Forteau 13 Quebec. The Low-water datum to which the soinnlinns on the .\ilmirnlty cluirt o. Queltec iiurhour are reduced, *vas recorded hy a Benc'i-mark, and is thus deflned hy a note on tlie harliour cluirt: — "The soundiuKs are reduced to the mean level of Low Water ordinary Spring tides; or 2H feet l>elow a Bench-mark cut in the sfoiu'work on the East side of the principal gateway to the Marine and Fisheries department." The tide gauge for Quel)ec was erected in 1803 at the masonry dry dock on the Levis side; and instrunu'ntal li-vels had previously been carried over from the Admiralty Bench-mark to this dock by Mr. H. Steckel of the Public Works department. The lieneh-mark at the dry dock is a cojjper plug driven horizontally into the face of the second altar stej) from the top, on the west side of the dock, near the inner end: and it is numlx'reil l.vxiv in Mr. Steckel's series. The elevations of the two Hench-marks, referred to his own datum, are as follows; — Admiralty Bench-mark, 27 •039 feet; Bench- mark Lxxiv, 21 -tiU) feet. The Low-water datum for the tidal observations from 1893 onward, was therefore taken as 22-58 feet below the Bench-mark, to corres- pond with the Admiralty datum. The recent levels by the (leodetie survey in 191."), nuike the difference between these Bench-marks to be 538 feet, instead of 5-42 according to Mr. Steckel's determination; and according to this new value, the Low-water datum at the tide gauge differs by 0-04 of a foot from the Admiralty datum as defined by the Bench-mark on the Quebec side. Comparison of Datum levels. — The various datum levels used at Quebec are defin''d by the following relations, which enable them all to be brought into relation to the Admiralty datum. Royal Engineers' datum. Adopted as mean tide level in 1864, and used as the datum for their contoured plan of Quebec; at 7-76 feet above Mr. Steckel's datum, as determined by him from the Royal Enginec- ' Bench-marks. Datum for the St. Lawrence, established by Mr. R. Steckel in 1880-82, and defined by the following elevations: — Elevation of the Admiralty Bench-mark 27 04 feet. Elevation of coping of the Louise dock , 24 02 feet. Datum of the Queliec Harl>our Commissioners. Defined as 24-00 feet below the coping of the T.,()uise dock. The elevatiuM of the Admiralty Bench- mark above this datum is 27-0.") feet, as determined l)y Mr. St. fieorge Boswell, Chief Engineer, Quel)ec Hari)oiu- Commissioner^. r.Ii-varion. Bench-mark, defining the Admiralty datum 28-00 Royal Engineers' datum, being their fleterminatiun for Mean Sea level at Quebec 8-72 Steckel's datum at 27-04 below the Admiralty Bench-mark. (See his Report of 1891.) 0-96 Queliec Harijour Commissioners' datum from thrt-e evaluations as follows: (1) from Steckel's determination of the actual zero of their scale, on the Harbour Commissioners' wharf, 0-94 (2) From elevation of Admiralty Bench-mark, from levels by St. George It BoMvcll, Olt.i ,.j) Dofinrd ns 24 feet hclow copiiiR of tlu- I, " ^^arch 18!)!) to March I!)00 " March 1!)00 to March 1!)01 " March H)01 to .March 1!H)2 " July 1!)02 to July 1«K)3 July 1!)03 to Julv 1904 (.\(inii>'sion to gauge impeded Iiv accuiuuhition of nmd.) One year, from April 1!)05 to .\pril !!)«() " April 1!)0G to April 1907 " .\pril 1!)07 to April 1908 " .\pril 1908 to April 1909 " April 190!) to April 1910 " April 1910 to April 191 1 Iry dock ow-water itioii: Ki.t H ■ ti.Vt S • ."lO!) S-491 K.(}48 ,S-.")»i3 S • 575 K-.542 8 . ♦i90 8-7G3 S-(i24 s-517 8-444 8-749 8 -042 8-870 8 523 For sixteen years. Cleneral average .S-til3 The result for Mean Sea level or half tide a> determined at the Levis dry dock, is thus 8-61 feet above the Low-water datum, or 13-97 feet below Ik-ncli- niark lxxiv. The actual elevation in the series already given is n()-39 which enables it to be brought into relation with any other tide level or datum. If correlated with levels on the (Juebcc side, the assumption is involved that there is no slope in the Low-water datum from the Quebec side to the Levis dry dock. liifcr slope at Quebec. — ^lean Sea level or isical half tide ;it (^ueljcc as found from the hourly ordinates of the tide, is undoulitedly higher by ab(jut 1^ feet t!ian the true mean level of tlie ocean. .An evaluation of this differen(-e from connecti(m of levels made at Rouse's Point with the New York lines, was fully stated in a Paper by the Superintendent of the Tidal Survey, jjublished by the Canadian Society of Civil Kngineers in Noveniber. 1908. The differeiice then givr-ii Was 1-40 feet, ami wlu-n corrected in 1914 for later delermiualion.-^ in the series of connections, it becon>es 1-52 feet above Mean Sea level at New York. The through levels of the ( ieodetic survey give the following result, from ^lean Sea level at Halifa.x as checked at Father Point : — 16 lii'iich-niiirk Lxxiv :it I/vi-* dry /(.«. -The follottiliK tiilile nives tlle extreme levels of tl for II series of sixteen year*: ami it is confined to the open season from to Novemlier 30, because in the mid-winter months and ulso when the ice out in the sprinn. iiny piirtial ohstruction of the rivei may cause irrenula the levels which is not due to true tidal influence. The low stajfe of the in tht river towards autumn has also an elTeet: and in the Low-water seri^ extremeH an* theri'fore in the autumn. Kxcil>liiiii.il nii;li \\;iMi>, ;ilii)Vc lilt' I.iiw-w^iti 1 il;ili'!ii. I), 11'. lli'lKiO lltOl. iDtrj. \m.\. l<.K).'i. Mtiy .lUIlC ■lulv Mav Muv Nov-, Nov. Miiv Nov. Muv Muv Nov. Oct. M..V Muv Muv 19 H ■J7 Itl 10 .. , , JO iM) feci Jl -JO " JO*) " JO-.-jO ■• JllO " 1000. l!K)7. ItlOH. toou Itl 7 :m •JS 'JllHt " -JJ-J.-i •• JItHt " "Oiir> " HtlO. I'.lll. lltlj. 10 2 2h JOliO •• JO-HO •• Jl-7."> •' i<)i:t. 1014 nti.i. 1!»10. •> 1 IH JO- 10 " JO-.V) ■' :;0.ii from .May I I thp ice move* irn'KiiIiirity in ;f of the wiiffT ■atiT siTic-*, til" iVllllTs. r italiiin. IIcIkIi!. . . . - fj (Ml flHit. ... "il •.>.•) •• -() 10 •• . . . -() 1.-. •• . . , -^) ;i.i •• ... -i) f.5 •• ...—() r,») •• ... -H) m " ..,—() 20 •• ... — 1 (XI " . . , — () i"i " . —() 4-. •• . ~() '.Ml •• u.W ,\h\ n.)l full I' MCllWHl rst bars ab'ive 1 show unusual the river level 'alls gradually usual change ucisely stateil. al low water.-; r navigation. Us lower than le lowest Low At the highest fltKxl Htanes, the iowe«t Low Water* iim> l>e Icnn after iln' nuHtn'N quarters, and they may even lie us late a« the date of the ,v \t new or lull miKin. (At Quobee, LAV. at Ni ip tide" is on the average 2j fe and 1887. Th< are for a period of one lunar nnmth in the autumn when the river is at its lowest stage, and one lunar month in the following spring at the high stage of the river. The effect of the variation in the river level upon the tidal undulati(m, will be seen in the tables below. The heights are all nduced to the uniform datum establisned by Mr. Sieckel, which extends from Quebec to Montreal; and they thus indicate the slope of the river as well as the amplitude of the tide. The observations are given in full detail in his Report, dateil November, 1891, entitled "Water Levels, River St. Lawrence, between Quebci and Montreal;" issued by the Public Works department. The locality in the river which is of most importance in regard to the depth available for navigation, is at Cap k la Roche; where there is a bar of rock and heavy boulders, on which dredging has been done for several years. Tidal observations were obtained here during the two seasons of lOO.j and 190(5 with a registering tide gauge; and during the four previous seasons, from 1901 to 1904. the Semaphore record was obtained, which is equivalent to scale readings at evf'ry six inches, in the rise and fall of the tide. From these six seasons, the time-differences with Quebec have been obtained, and their variations determined, by which the Tide Tables for Cap il la Roche are calculated. In the tables below, the mean High Water at Spring tides is found by taking the highest average for the two tides of any one day, ar' well as the mean of the two Spring tides in the lunar month. In this way, both the diurnal and semi- monthly inequalities are eliminated, which gives better comparative values, when each period of observation is limited to a single month. The Low-water value is not always at the Springs, as the lowest levels occur nearer to the Neaps in the upper part of the river, as already explained; but the inequalities -ire eliminated in the same way. The values given in the column headed. Greatest difference of level, serve to indicate the decrease in range as the tidal undulation 28186—2 aM-'DiU thr riviT. A nmrkod i-hni)K*>. uii ling «'» tlu* xtaKcof thf rivi-r, <» at thi' Hirlii'iirti riipiiU, iMtwtrn Point I'lufon anil Crondinrn. Tin- nlmrrvn ttt (iuflM'c wiT«' Inkin iil the dry dock on the F/vi- «idp; which i^ thi> i loc-ntioii iiH thi' Tidal Siirvcy kauk<> now ha^'. Thf ijatiini r«.tai.liKhi'd hy Mr. Stcckil, to which nil the hcixht!* arc n-di i» at OtMl f(M)t alKivc th«' Ailiniraify I.ow-watcr (lutiini at {^uchiT, an nhoM thi' r(tnipnri«on of datum Ii-vi-Ih already given. The Low-wnter levlx a« '>u and St. Nicholax have negative values at the low «tage, until the Klope ol river Itringx their elevation above datum. II Kilt STAdK OF rilK HIVKK IS THE SI'HISU. Tiut Uvtut (luriiiK ww limur iDonth, Muy I to Jim« A, 1HHJ4. !.tU 24 4tt •aw, 22 .« 21 17 IS fl2 17 ti4 .Mriiti of loWf'Mt L«iw WatrTM 21-42 ■nam mm i:i-74 7 4ti .{ «> l-.'M) Kxtn-nir I Low Water. |i 20 »17 lit 47 \hm i:i>02 tk-3l( 2-15 0-80 C of tli<> i On-Ill. -Ht (liffrrciicp of Ifvel. S.7H 10 HI ttl«9 10 (M (Jrpateit •liflfrrncf ofli\ • 4 90 5-74 «-27 1!70 l«-53 18 '40 19 72 ie ruled a-* a line acroMN the face of each diagram i.litained l>y the recording instrument. The fnl'le given Im'Iow illu^tratex this, in aeconlance with the general imtlaxU already dejtcrihed. It ^hoWH the levels of Low Water lir.st as reailings mi the diagram or tide ncale, and next as reduced to the l.ow-water datum. This table is for Orignaux I'oint which is <|uite iM-hiw any river influence on the tidi levels. TluTc is an Admiralty datum hen-, defined l>y a lienih- mark: and the zero of the title scale was connected with it liy instrumental level)*, thuM enuliling all tide levelx to l)c> brought to definite eh'vations. Liiriililv ami Duo- in KMNI (iritrtittiiM I'oint. Jiiitc 'ilV July l.-i .Inly '.N .Van. i:» Auk. '.'.V ■' Sept. U). I^w Watkn at Hpnimw. Height on tide M'uk'. From l,.\\ . datum. Mnun'N phttM-a anil diitanrc. .VviTiiKc I..OW Water. Ilciidit of (lutuni on scale .\vcrago L.W. hImivc liutuni. t-."i»l feci +11 .Vl foot N'l'tt Moon Mniii iliotuncr. i Mi " +0-11 " riill|MiK)n. .■i:«) " i +1 :i«t flit .\(w'MS0 " +1SI1 " NcwMoon. Xiiir .\|KiKrc. -'.'•Hi jFull -Moon. I'rrigcc. .\vcrage I-ow Water at S|)ring tith's, is llnis the average level of the lowest Low Water at each Spring tide during the season, wlieii i)alanceil for the semi- monthly inefaineil here, extended from May 4 to Octoher 15. At (irt>sse Isle there are two wharves on the sitle of the island f.-icing the channel of the river. The AiUk ;alty Jlench-mark is a ring holt, let into the rock at High-water mark, situated 200 feet west of the West wharf. The level of Low Water at ortliniiry Spring titli'.'i, to which the sountlings on the chart are reduced, is at 21 feet 10 indies below this Hench-mirk. In using this ring bolt as a Bench-mark, the point taken for reference was the top of the eye through which tlu^ ring inisscs. A second Bench-mark consists of a copper bolt tiriveu vertically into a flat piece of rock at the High-water mark; at 53 feet northeast of the ring bolt, and 70 feet south of the Quarantine building. Marked "C— B.M.— J" 2818&— 2§ 20 Top of ofip at outer ctnl of West wharf - '^J'j] HiRhost known HIkI. Water at the SprinR tides of Fel)ruitrv. 1,S!»4, as marked at the time t.y Captain LanRJois, wJio resides onthe island. The more trustworthy murks Rive tl,.- level of this hiRli wat.T as 102-85 or 103-3:}. Hest mean value jo Beneh-miirk.— Top of eye of ring holt, us above deserihed. Klevution adopted . Keoond Beneh-murk.— Top of eopj.er holt as ahove d<>seril)ed. ason of 1000, on September 12, during a gale ,,, Highest level of High Water undisturbed bv storms during the se-ison of 1!»00 ,j, Average level of High Water at ten Sjjring tides during the .<«ea.son '>}] Adnnralty Low-water datum, at 21 feet 10 inches below the ring bolt 7> Lowest level of Low Water recorded during the season of HKH), on September II The maximum range of the tide on the whole length of the St Lawrei occurs at Gros.se Islo; as the true head of the estuarv is in this vicinitv below Orleans island. It is thus of int<-r.st to note that the average risi .Sl)rmg tide.s is 19-7.1 feet above the A.lmiraltv Low-water datum, and greatest known rise in February, mi, is 24-84 f.vt above that datum. Crane tdand i/7(a:/.— Tidal observations were obtained here in the sea of 1008. They were taken simultaneously at L'Islet; the object being obtam data for the time and height of the tide in Beaujeu channel which betwe.'.! these two localities. This is the only dredged channel below Quel and the tide scale used by the Ship Channel survvforthe dredging was nla at Crane island wharf. The average level of Low Water, as observed simultuneouslv at eight Spr tides durmg the season, was used to transfer the original Admiialtv Low-Wii datum across from L'Lslet. The Low-water datum for the dredging was tl found to be 0-2() foot b,.|ow the Admiralty datum at LTslet; and it has theref been adopted at both localities as the datum from which to measun- the rise of tide, us It corresix.nds better with th.- seri.'s of datums in this region. Th.- dat IS thus correlated also with the dredging in Beaujeu channel. As regards this method ,.f transfer, the following remarks muv be made '1 ave..-ge range at Spring tides, as shown by the simultaneous' observati<.iis IftOS, increa.ses from 18-18 feet at I/Islet to lS-y Bench-mark. A horizontal groove cut on the stone fouiulati. at east corner of lightkeeper's house, about one foot from the itroun.l. The l-tf i S." are chiselled below it. KN'Viificin. I, as iud. r as tioi) sf.T Iter oil 103 01 HH)(K) ••S-,1 !»S-GO it7!t2 78-17 77 • SO :. Lawrt'iK't', icinity, just rage rise at tn, and the latum. I tho season t hcinR to I, wliich lies jw Quebec: was placed 'iglit SpriiiK Low-water e; was thus !is therefore e rise of the The datum iiade. The rvations ot As there • at the two r, wlien the (1 tiierefore rs in actual innulation, Th<' l.'tter- 21 Bench-mark of the Shii) Channel survey. A nail in a tree i)ehind a sIumI at head of wharf. Elevation 2t)-4(i feet above the zero of the tide scale; and I -'Ao feet above the Tidal Survey Bench-mark. Klc'\ MtlMII. Bench-mark as above described. Elevation adopted 100 00 Average level of High Water at eight Spring tides during the season: 1808 feet above Admiralty Low-water datum 01 • 13 Admiralty Low-water datum, as transferred from Llslet 7.")- IT) Zero of scale of feet placcil by Shii) Channel survey: tlie zero being the Low-water datum for the dredging 74-80 Lowest Low Water during the season of 1008, on Octolier 14 7l-4."> Bottom of channel as dredged; at ;{() feet below the Low-water datum given by the zero of the scale 14-80 Biaujeu channiL — The resulting tide levt'ls for tlie dredge than in the Quebec Tide Tables. L'l.skt. — Tidal observations w 're obtained here during the simultaneous -cries of 1000, from .ALiy 12 to October 15; as well as in 1008 as already mentioned. The Admiralty Bench-mark is a broad arrow cut into the face of a vertical rock, at 30 feet east of the imier end of the pier at L'Islet. Tlie level of Low Water at ordinary Spring tiiles, to which the soundings on the chart of the Traverse are reduced, is at 34 feet below this Bench-mark, its elevation al)ove Mean Sea level, as determined by the Ceodetic survey, is 20-0-") feet. On the face of the same rock, a little lower down and to the westward, a copper bolt is let in horizontally, !ind is marked C.B.M. (( i(i\ ernmeiit Bencii- mark) Xo. ct,iv. The levels at L'I>let ;ire as follow-: — i:i. \iition. Admiralty Bench-mark, as aiiove. Elevation adoi)ted. lOO-OO Coi)]>er bolt above described: cross-line at the centre 0S-20 llxi-ejitional High Water recorded in the season of 1000. on September 12. during a gale 8(>- 10 I 22 AveniKr level of High Water at oiRht SprinR tides .luring the season of Average level of High Water at eleven Spring tide, .luring the season of Admiralty Low-water datum, at 34 feet in.'hes hclow their Bench-mark C Low-water datum of the Ship Channel survey, transferre.l as alrea.lv explamed from their tide seale at Oane island wharf " (j Lowest level of Low Water reeorde.l .luring the s.-ason .)f 190o! on September 11 Lowest level of Low Water, season .)f 1908, .m September 11 . ^ ' . . . . (j The soun.lings on th.- Admiralty ehart of " The Traverses " which ext- to C..).)se island, are referre.l t.. the Admiraltv datum at L'lslet In two sci- m lOOO from May to Oct.^her and in 1908 from .lulv to November, there were Sprmg ti.les that fell below that datum; the lowest of these being 0-68 of a below It, which corresponds with the elevations above given. On this chart, the Low-water datum is also defined as 29 feet oj^ inche- b. the base of North tower of L'lslet church. This second Bench-mark wa. .'stabhshed by Commander Maxwell during the Admiraltv surveys- but it is very rehable as a Bench-mark. The r<>ference t.. it, and the connection of ' ' Bench-marks made by the C,e.).l.>tic survev, woul.l give GG • 29 as the ele^ , the Admiralty datum, or 3\i inches higher than the other. This cannot I. accurate as the reference to the Bench-mark on the shore, as above given ' second Bench-mark was no doubt established for gr.-ater securitv, to preserve important datum in the Traverses. Orignaux PoinL~T\ns is one of the eight ti.lal stations in th.' St Lawn estuary at which simultaneous observations wer.' obtaine.l in 1900. The t observations obtained here, extended from June 22 to September 11 The Admir 'ty Bench-mark at this point, is a broa.l arrow cut .,n a si, vertical face of rock, facing the east; at a distance of 37i 2 feet west of the in end of the wharf at this point; which is termed in the Railway time tab Rividre Quelle wharf. The correct Icv.-l of the Admiraltv Low-water datun 23 feet m inches below this Bench-mark. Its elevation above Mean S.-a I.m as determined by the Geodetic survey, is 13 Gl feet. On the first of the recent series of charts for the St. Lawrence .wtuary iss. by the Hydrographic survey, entitled "Mai bale to C;oosc islan.l " A.lmiralty Low-water datum is adopted, as al)ove defined. The lower part of Traverses is comprised in the area of this chart. Top of caj) at the head of the wharf at Orignaux Point "05' Bench-mark as above. Elevation adopted jy^, E.xtreme High Water; said to r.-ach the top ..f sheet i.ilingprotecti..n about mne feet i)el.)w top of cap. C.)rrespon(ling elevation %. Highest level of High Water recorded .luring the ..casou ul 1900 on July 1.') an.l August 11 ' .,- 9.) • mk 23 ason .... 84-75 m of .... 84-17 )n of . ... 84-10 ark. (JtJOO •ady tir)-74 , on (l.VtJO . . 65-32 hieh extend- two seasons, lere were five •68 of afoot inches below ark was also but it is not jn of ' ■ two ele-s ,n of •annot be as ;ivpn. This preserve the ^t Lawrence The tidal : on a small of the inner time tables, er datum is n Sea level. liary, issuetl *land," the ■ part of the KIcvation. 105-37 100-00 (The extreme High Water of September 12 wa.s not recorded here.) Average level of High Water at six Spring tides during the season of 1900 05-22 n, m 06 00 05 • 70 Admiralty Low-water datum; sit 23 feet IJ^ inches l)elow the Bench- mark. Also adopted by tlie Hydrographic survey 76 -8S Extreme Low Water; .said to lay l)are the mud at inside angle of wharf behind the heail. Corresponding elevation. . 74-00 Lowest level of Low Water recorded during *he .icason of lOOO. on September 10 74-75 Cap a I'Aigle. — On the north shore of th(> St. Lawrence, ininiediately east of Murray bay. Tidal observations were taken as scale readings for one month in July and August of 1905. A Bench-mark, established by the Hydrographic survey, is a broad arrow cut on a flat faced boulder at 1.50 feet north-east of C'ap i r.\igle wharf. Thi.s Bench-mark apiiears to have been destroyed subsequently, when all boulders were removed for filling the crib work of the new wharf. The Low-water datum used for the reduction of the soundings of the Hydro- graphic survey in this vicinity, is at 17 fret 7 inches below the Bench-mark. T'le two Spring tides observed. indic;ite that this lev<>l corresponds well with i.ie datum on the south shore. The tide levels, relativelv to the Low-water datum, are as follows: — Fret. Bench-mark as described; at 17 feet 7 inches above datum 17 -.58 Average level of High Water at the two ccjusecutive Spring tides ob-^erved 17-45 Average level of Low Water at these two Spring tides 0-50 (Extreme Low Water, not ascertained as the olxser vat ions were not continued throughout the se:ison.) Low-water datum 0-0" Rivihre du Loup. — One of the eight tidal stations in tlie St. Lawrence estuary at which simultaneous observations were ol)tained in 1900. The.se observations extended from June 30 to October 17. Further observations were obtained in the season of 1905, for two months from July to Sentember; taken as scale readings by the Hydrographic survey. The Admiralty Bench-mark is a broad arrow ^ut into a vertical face of rock, facing north; at 100 feet westward of the centre of the flag pole which stands on the highest ground of Riviere du Loup Point, near the wharf. The elevation of this Bench-mark above Mean Sea level, as determined by the Geodetic survey, is 16-98 feet. The Admiralty Low-water datum is at 24 feet 2 inches below this Bench-mark. The datum used l)y the Hydrographic survey for this region is 26 feet below the Bench-mark. The Admiralty datum is too high; as it is not as low as the average of the Low Waters at Spring tides in 1900. On the other hand, the Hydrographic datum is too low. To obtain a Low-water datum at a level, relatively to average Low Water at Springs, which corresponds with the datum elsewhere in the estuary, a foot higher should be taken; or 25 feet below the Bench-mark. This is necessary in the present comparisons, to make the rise of the tide consi.s- tent and comparable throughout the estuary. 24 Bciu-h-inark as vl.ovc. Klcvution adopted '^O Exceptional Hijjh Water reeor.led in the season of HKK). on Septemher 12, (lurinK a pale „, Highest h'vel of Hijjh Water, undisturbed by storms, during the season of 1900, on July 14 ,,. Average level of High Water at six Spring tides Vluring the season of 1^*^ .,1 Admiralty I.ow-wat.r datum, at 24 feet 2 inches l)elow the Bench- mark _. Average level of Low Water at t he six Spring t id.-s d,.ring t h.. season of Low-water datum adopted, to corr.'spond with the datum elsewhere, as above explained Lowest level of L(,w Water observed during the two m.mths in the .season of 1 <»()"). on Sep'. ember 1 -, Low-water datum of the Hydrographie survey .-it 2(3 feet below the Bench-mark Lowest lev.4 of L..W Water recorded during the 3J months in the scascm of HKKI, on Septendx-r !(» -.j TatMions at which simultane^ observations w.re obtained in 1000, from July 11 to September, 15 Furt observations w.re s.^ured in 1907 and 1908, with a registering tide .uiuge co-operation with the Hyc'.rographic survey. The record obtained ext^iids fr June to Dccemljer m 1907, and from June to November in 1908 A Bench-mark was established in 1907 by the Hydrographie survev, i on the cliflf opposite the north-west corner of the steamer wharf at L'Anc. 1 Eaii, which is the lar ■ g for Ta.loussac. It is a broa.l arrow cut in outli on he rock, and .• xed "B.AL 07". The Low-water datum adopted bv 1 Hydrographie s ....y for this region, is at 19-20 feet below this Bench-ma Ihe lidal survey observations of 1900 were correlated with these later obs vations by means of average low water in the three seas.ms, as follows:— 1907. Average Low W.-.ter at 14 Spring tides un"-"l Average Low Water. Mean of fourteen Si)ring tides in 1007 and twelve , in 1008 '^•••^•> Low-water datum adojited l)y the Hydrographie survey and correlated with the observations of 1000, as exi)lained SO-80 Lowest level of Low Water in the sea-son of lO(K). on Septeml)er 10. 70-3.j Lowest Low Water during fi^ nnmths from June to December of 1007, on October 22 ""--^O Lowest Low Water in the season of 1008, on September 11 70-40 The Saguen.w.— The lower Saguenay from Tadoussac at its mouth to Bagotville in Ha ha bay, forms a deep-water inlet, .").") miles in length, the depth t)eing not less than 100 fathoms throughout. It thus presents the tidal char- acteristics of dee]) inlets, such as those in British Columbia; anf Low Water The greatest r is low, and ?e of Spring test; and the lowest stage, f Low Water unar months II as diurnal um. m. im. jm. im. m. 3-48 ft. 1-61 ft. 002 ft. 0-50 ft. 2-14 ft. are in Feb- ' end of the ire the con- ■, 1913, and p tide which lie, it would In the season of H)lo, tidal observations were obtained with a registering tide gauge, from June 18 to November 15. The elevation of the zero of the tide scale placed beside the gauge, was ascertained by instrumental levels; and by the usual system of compariscms with this x-ale, the g;iUK<' record was accurately reduced to a uniform datum, i-orrehited with a liencii-mark, accord- ing to the method always adopted. The Public Works Hench-mark is on the river bank, at 2.')0 feet west of the upper side of the steamer wharf. It is the surface of rounded granite rock immediately beside a broail arrow cut flat upon it. and ni;irki>(l by a large " .M " chiseled on the rock beside it. '"'u- Low-water datum is :it 21-30 feet below this Bench-mark. The top of an iron Ballard po.^t, filled with concrete, at the west end of tin- wharf and back from the face, is also used as a Beiicii-mark. If was disturlu'd l)y an accident to the wharf; but its present elevation as found in lOlo, is given below. A scale of feet is painted on the concrete face of tlie wharf l)eside the steam- i)oat slij). Its zero is presumably at the Low-water datum; but in painting it, a progressive error was made; and at the upper end. 22 feet as painted is at 21-80 above the Low-water datum. All the tide levels here, are corrected for the discrepancies indicated, and reduced truly to correspond with the Bench-mark on the rock. KIt-vution. Top of iron Ballard post, as above described; by levels (jf 1915 103-43 True elevation of 22-50 feet cm the painted scale on f.ice of wharf. . . 101-00 Pul)lic Works Bench-mark, (m granite rock, as described. Elevatitm adopted IfX^'XI Extreme level said to have been reached i)y High Water of a November tide; year not known 100 • 1.) Highest High Water in the season of 1915, at perigee Sprinj-s on Xovem- ber9.. *'«•<"' Average level of High Water at ten Sjiring tides during the season of 1915 i'«»^ (For the levels of Low Water during the season, see >t:it(nieiit ul)ove given.) Low-water datum of the Public Works dci)artment, at 21-30 below the Bench-mark Lowest level of Low Water in the season of 1914. i hi Aujiust 0-U) below datum, and in October 0-04 below i 78-00 Lowe^. level of Low Water in the sea.son of 1915. on .-^eiitembcr 11 . . . 78-45 Bottom of dredged channel to wharf, at 10 feet below datum 02-70 TroiH Pi,sly Escoumoins.-Tkh\ ulKservations w.-r.. ohtaine.l here, with a n-Ristc tide KauRe suppiie.I to the Hy.lroRraphic survey, .luring a nu.nth in the aut, of mo and th.>y were .•ontinu(..| in th.. season ..f Kill fr.mi Jun.. Ui Augu.st 14. The Bench-mark is a broa.l arrow cut .,n the east fa.-e of a flat r..,l r situated 94 feet west of the inner end of the wharf. From this tidal record, a L..w-water datun. w"as detcrmine.l bv this Sui to cormspond with the datum cIsewh.Te, and to give the ri.se of the tide relativ Ih.s datum .. at 1 • L5 feet below average Low Water at Spring ti.les, or 12 eet below the Bench-mark. The ti.le levels in r.-lation to thi.s datun. ar iollow.s: — Average^ level of High Water at four Spring ti.l..s i„ .Iu„e and .July, Bench-mark as abov.. (I.s.iibcd 1.-) 12 Average h.v.'l of Low Wat.r at th.. san... four Spring tides 'i Low-water .latum as adopted . Jcrenn, i.sht.s.-Tln, lo,.ality was pref.-rred to Bersimis for ti.lal obser t.ons as ,t IS on the open, an.l not obstru.'ted by a bar, as at Bersimis riv lidal observations were ..btained here, with a registering tide gauge suppi to the Hydrogrupnic survey, in the seasons of 1913 an.l 1914 \ ti.le se was set With Its zero at the Low-water .latum a.lo,,t..,l bv the Hvdr..grapl survey, and the levels are definite in 191.3; but in 1914 the ....mpadsons tak w..re unreliable for both time and height, so that the r.-gistering gauge .vas i correlate.1 w.th Ihe tide scale; and all that c.ul.l be obtained from the r.-cc was the ran^^o .,f tlie tide by difference of level. The basi. .,f the tid.. levels given below, is therefore cxplaine.l carcfullv. •Jft I' Miricli 000 al observa- simis river. Re sui)plic(l . tide scale ■drographic isuiis taken igc ,vas not 1 the record ic levels us The Hench-mark is a Imiail arrow cut in the rock on the north-east ext «)f the snuill ishmd formiuK the wextern entrame point to Jeremy '. ay Low-water ilatum adopted l)y tin lIydro(jraphic survey is at U-71 feet this Hench-mark. The tiilo levels in relation to this datum are uh follows: Hiiilx'st liixb Water, in the season of nti;<, on October 2 Ilench-niark as above described AveraKc level of Hinh Water at six Spring tides in the sj-itson of 1013, from July to October The mean Spring ran^e at five Springs in 1014 is 13- 13 feet. .Vssuming thin range to be above average Low Water at Spring ti best levc-ls for Low Water at the six Spring tides in the season of 1013 Low -water datum, as above defined Lowest L(»w Water in the season of 1013, on August 4. ( Below datum) remit y . The ImIoW Vn-t. 10 •.•)0 14 71 14 t>4 14- 10 1()«> 00 -0-.')0 F.\THEU POINT.— In the early days o. the Tidal Survey, the endeavour was made to compute the tide at Father Point from (ii'cbec to avoid nndtiplyitig the principal stations. But the relation was complex, involving a double scries of variable differences for the time of the tide, and the result was not satisfactory. It was* therefore decided to make this int.) a principal tidal station for the St. Lawrence; and this decision has been fully justified, as it has proved possible to refer a very extended region to it, as explained in the Tide Tables. Tidal observations were begun at Father Point in Deicmber 1804, by means of a registering gauge installed to operate continuously, summer and winter, and working by siphoning. Careful comparisons with open water were taken, to enable an allowance in height to be made near Low Water. Owing to delay in the eon.^truction of a wharf at Father Point, the siphoning gauge was kept in operaticm longer than intended; and the later years were not accepted as reliable in the determination of Mean Sea level. The first complete year's record was lost at sea, in the endeavour to communicate the information to the Admir- alty. The years available for the dcterminaticm are therefore, from the siphoning gauge, 1897 to 1901; and from the open-water gauge when reconstructed at the wharf, October 1004 to date. The original Bench-mark established in 180,'< was the head of a copper bolt let into solid rock near High Water in the vicinity of the gauge. Its elevation was taken as 100 00 feet, and as it has since been covered by the gravel of the new road past the lighthouse, though it is still extant, tlie Bench-mark on the old lighthouse building has since been used for working purposes. These two Bench-marks arc within 50 feet of each other, and their levels have been accur- ately connected. In the following list, the extreme levels for 1900 are included, for comparison with the other tide stations in the simultaneous series of that season. Bench-mark on the old Lighthouse building: a chisel line on a copper plug drilled horizont.'illy into the stone foundation on thi- ea>t side, at 3i feet from north-east corner, anil marked "C — B.M. — H " M) Hi'tich-iniirk, iw uhove il«'Hcriin'i| Original Tidal Surv.y n.nch-M.urk of IW>:,. n.,w ,.„v.t.'rvation, Ix'twocn 1«<>7 and 101 1 ; at 7r)()0f..(tal)..v<. Low-watiT,lutuni. (Sc- details Kivon Iwlow) I-ow-watcT .latum, as ..stal.lish<..l in 18!>7 f..r tho siph.minK khuk.-. an.l transferred at th.. sum.. ..levati..!! in 13-3l ic tidf l(»ll; ow).. Hti'il I', mill settlc- 78-l»:> ir tln> niciit ; )f the 7«00 78-50 r7-3l) 5, on '7 -20 cstiiJiii shed Ipv ic tide, (lurinR Kr.-f. 7--)41 7-. 568 7-«30 7-774 levj'l, jrily. ion.) 7-421 7-433 7-432 i 31 < >n<' yt'iir, from NovrinlxT MM)? to NoviMnlwr \WS. , , . , 7 t>«4 " June HHMMo June nno. 7 734 " " July HMO to July ntll 7-5H8 J For ton yt'urH. ('K'ntTui tivcrimf iiilopfiij.. "-.VM) An the Low-wiitrr dntuin if at 7805, thf I'lfviition of Mean S«a hvil whirli ri'«ultn in 80-5' •\» nlrciiily fttiitcd; unil tin- n»ii(li-niark o:i the old linliliiou-'c liuilding is found to hi- 17- Hi fi-ct aliovc Mean Sea level, ii« now dftcrmimd liy f hew ten complete yearn of tidal oliscrvation iiere. The elevation of this Ueneh- iiiark uroordinji to th;' levels of the (leoovi' indiiiited. The (leo .-ar, ur.. n-f.-rrr.! t., th.. (Je,.l..tic- H..,„ rork tlw. U.u.h. 5«, f,.,., fr.„n rl... «... «m|,. ,.f M/.rhi,„ whnrf. »t 321 f, It- or .ml. Th.. ..|..v».ion „f .hi. H..n.h-n,urk uJk.v.. M..«n S..,, I Minf.l l.v th.- (i..o<|...i<- ,urv.'.v. Im 781 f...... M.-n.|.-..mrk M.n, .xnx. i:i..va.ion a.|..p...,|. HiKh... I,.v..| of IliKi, Ua...r. lA 10 h1..,v.. ,l,t.,„n, in Um ,m .hmv IM "• |..;r.K... Spn„K,. .Th. .i.l.. n-mh..! Urn lovl «N., .luring (h.^ I iil»lic VVorkx <>h«..mi.i.nm in MMO on Jun.- M) Avrngo !..v,.| of High W„.,.r a. ..I.v.n Spring .i.!.. in 11)1/1 „n.l 1»1.J. (Of h...... .„,,. ,H H. ,h.. , ,„'. m..un .liM.,,, , an.l .h.. r.-maining .Mght ar- w.ll halanc.-.! in pair, in nlation .o IVrig,.,. an.l \,m,b,,. giving a .rii.' av.Tag.') ' "^ ' L .V^„<«.~Thi.s in prop-rly th.- .livi.ling point Ikh-wo^m, the St : " ''^""^>' "": »ho finif. .)|.,.rvationH wore obtaino.l h.To with a reg 1910 l.ut m ,ho firHt .s,.„..on tho .•on.p«ri..on.s which .l..f„u. th.- .sotting XrfoST r''',";'""T "•/»•« ♦"'•> -'-. wore too .lefi,.io." t.f am.rat.. IovcIh t.. be d.-du....!. In IfllO, th.. gauge was ,,laml at An. 'iToMiine^d ? r;r '"*^' ••' li""/ ''"- ''""^' ^'"•"' •» «-« ^'-- "^ «»-- i";:t i^indiig. "'' "'""^"-^ •"""^^" '""'^ '^ ''"" ^^''♦'^•^- «- *''-«'' - \ I. ^]";"''"^^»'-">"'-'' '« « '"-"^d arrow cut ... the rock where hight»t. at A la Morue at two feet north of crosn in front of th.- fishing .amp th^re ;hirc;.;;;::r " "'"' '" '"^ "^"-«-"»^- --■••>■ i^ '» i^'. ;:"• Mean N-a lev. was obtained from the hourly onlinat.. ..n the ti.le Aiiclun.. The ti.le levels ,n relation to this datum, are as follows: - Hench-iiiark as abov.- descriiied High.-st High Water reeorded in 1!»10, On Julv l.j ! Averju^e I..vel of High Water, from seven SpHng tid.. i„ the reason of Av..raKe Kvel „f Low Water at th, san.e seven Spring ti.les ' Of the.s,. soven ti.les. o„,. is at the moon's nu-an distance, an.l the remauung s,x are well balan,..-.! in pairs i,. rda.i,..n t... P.rig^e and Apog.>.', givnig a true averag...) Low-water datum, as defined L«w,.st Low Water during the 8eason^,fl9l(5,oaS,>pt.a,lMT 12 ■■'! -i ptlf H<(i(h-intirk ontnlly iritoKoli.l Ht 321 f.H-r frniii »n Mi'14 li'vcl, a- Jilrviiflix, l(N> (Ml nil' IS, iiK tli)> 1H» 2!i HMO. llllllllK I»"K<'<', iw n Kl feet MtM't r20 Sti • 2(i •tnlicr SOI.') >n the St. I.tiu- th a rpgiHteriiiK w of 1916 and sotting of the ■lent to cn^ihlc I at An.xf' ;\ la )f olw(Tviifii)n> hough most of ihtst, at Point p there. The •4.') feet below '. u \ alu(> lor ic tid p reeonl 1 withCriuKi-. 's:-- IV PI, 18 •4.5 12 •8.-) n of 11 02 ■98 the igee 00 -0- 20 fVi/i< Chill. Thin in one of thf light liilul Klation- iit whiih Kiniiiltiuieoii« ol.MTVftlionx wer.' uhtitini-il in 1!HK», from July I" to Oitohi-r I. The regiMering Kiiuge wax nt the wharf in the mouth of CajM' Chat river, whieh i-< f^urroumled l.y liar', thiit iM'gin to ^how at low tide, The water at the wharf «loi« not thereforf fill to it-, true l<-vel at ' v tide. The .JitTerene.- between the hvel at the gauge and the ofwu water wu^ found from rompariitive olwervationi, from whieh a ..■rie^ of eorreetions was dedueed for the lower hveU of the ti.h' n* reconh-.l on I gauge. Thi'se eorreetions apply to the last three feel at I-ow Water, and the luuxunuiii lit the |owe-er, a true avt..ige is obtained by making allowance for the variation l)etween I'erigee and .\poge<'.l l.ow-water datum ailopted, at 1()0 foot below Average Low Water, in aeeoni with the datum in this vicinity Lowest Low Water in the season of KKK), on September 10. Approxi- mate level y> ■•» i:< 4.-. 12 7ti 11 .Sll 1 (H) O'OO -0 20 Sle. Aniif iUh MonLi. Tidal observations were olitained here with a rcni- i.ring ti(h' gauge supplied to the Pul.lie Works department in 11(10, from ./uiy ;«) to September 20. Tiif ti.le Icvi'ls ar- refernd to tti" (lendetic Hench-mark -M.cixm.xx.kix, a clii.sel line on the end of a copper |)Iuk driven horizontally into the stone found;i- fion on west side of entrance to H. Saceviile's residence, on south side of road. Sti'. .Vnne des Monts village. i:icv.it ion ai)ove .Mean .'^ea level, 1>.)\H feet. I-.ifVution. i:icvatioii adopted for tliis Hencli-mark 10(1 ()(» Highest level of High Water diiring the two months observation in 1910, on .Vugust 22 fSO • N.") Average level of High Wafer at four Spring tides in the two months . ,S(i-4() .Vverage level of Low Water at the same four Spring tides Tlj-.'JO Lowest level of Low Water during the two numths in 1910, on .Septeni- ••"'•20 7o.70 l.ow-water datum adoi)tiMl, at 0-90 foot below Average Low Water, to correspond with the datum elsewhere 7.'i-4() .M.sti ;{ 34 ST. LAWRENCE ESTVAUY.— LOW WATER DATUM AND RISK OF TIDE Average Low Water is average level of the lowest Low Water at eaeh tide. Influence of moon's distance may cause difference of 2 or 3 feet b the two Springs of the month. These are carefully balanced to obtain true i Low Water. The rise at Neap tides where determined, serves to indicate r of Neaps to Springs. Locality. Quebec Quebec Cirosse Isle Crane island wharf. L'Islet L'Met Orignaux Point. Cap h I'Aitjlc. . . Description of Datum. Datum below .Vverage L. \V. at Spring tides. Admiralty chart datum. . . Ship Channel survey ila- ttmi at ()'2l> below Ad- miralty datum at L'Islet Admiralty chart datinu. Hydrographic Survey da- tum Riviere du Loup. Hydrographic Surv. datum Tadoussac Tadoussae Trois Pistoles. . . Esooumains Jeremy islets Father Point ... Father Point. . . . Matane Gninds Meeliius. Point des Monts. Cape Chat JTidal Survey datum St. Anne des Monts. . " " Low-water datum at 2.5 feet below Admiralty bench mark " Tidal Survey datum. Tidal Survey datum Hydrographic .Surv. datum Year. In 1900. In inos. In 1900 In KMJH. In HKX). In 1908. In 1900. In 1000. In 1900. In 1908. (Approx.; In 1911. 191.3-14. In liKXt. In 190.S. In 1910. 191.5-1'. In 19 hi. In 1900 In 1910. Feet. 109 119 0-9.") 0-2t) 0-7t> 0-2.5 18 In 190.5. 0-.50 0.5 0-.55 Oo8 1-20 11.5 lOfi i;« 1-43 1-08 0-9.5 0-9S 100 0-90 Spring Rise above L.W. datum. Feet. 18-21 18 ,53 19-75 19-24 18-36 18-43 18-34 17-4.5 16-37 lti-27 16-91 15-82 15-3.5 14-42 14-04 l-.'-«7 12-72 11-95 11-92 11-80 1100 OF TIDK. ST. LAWRENCE ESTCARY. — VARIATIONS IN THE TIDE. r at each Spring The table liere given shows tiie variations in the tide with the moon's 3 feet between distance, when Perigee and Aj^i-'cc fall at the Springs; based on the actually ain true average simultaneous oiiservations throughout the estuary in litOO. The Neaps are ndicate relation also given where they have been determined. Such a comparison must be based on the ranc ! iiie tide, which is the true amplitude of the tidal undulation, independent < ' ai\' (:ut.:ni 'k:--\. The mean Spring range given, is the average as found for i '\e Avholc s'-.ison. lise X fiip Rise above turn. L.W. dutum. Feet. .'1 13-28 i3 13-22 '5 14-7.5 14-05 13-35 13-40 12 -S8 11-80- '1 ■ > 4 9 7a 7 10-34 2 5 o to 8 feet. 2 5 to 9 feet. Locality. Date, 1900. He'.;ht above U.\TrM. H. \V. L, \V. .Si'KIMl Ra.nue. Quebec. Grci! Isle. , . •" L'I«let. Orignau-x Pt. .Aug. 25 . Sept. 10. Sept. 24. Oct. 10. Oct. 24. .\ug. 25. jSept. 11. Sept. 23. Oct. 10. Aug. 25. . Sept. 11., Sept. 25. . Oct. 10.. j.Vug. 25.. Sept. 10.. 3 it Riv. du Loup. , . . i .Vug. 25 . jSept 11 Sept. 25. Oct. 10. 28186— 3§ Feet. 1(5-80 18-00 ir.-20 19-8) 16-50 IS -25 20-45 18-05 21-30 1710 19-00 17-00 19 -(io 17-25 18-85 Feet. 1-10 -0-15 1-00 1-00 0-70 1-15 05 0-95 0-05 1-50 -0-15 1-35 0-25 1-90 -2-15 I'erige*' . Apogee. Mea.n Range. Differ- ence. I Feet. 21-00 Mean . . 15-45 ' 2-30 I 17-45 ! -1-.30 18-75 15-30 2-25 17-75 -1-20 18-95 Mean. . . Feet. 15-70 18-15 15-20 18-80 15-80 Mean 17-10 20-40 17-10 20-65 Mean 15-60 19-15 15-65 19 -to Mean 15-35 13-15 13-05 Feet. 2-45 2-95 3 -GO 3-(0 3-00 3-30 3-30 3-55 Springs 3-38 3-55 3-50 3-75 3-60 5-65 5-65 5-60 5-70 5-90 5-73 Feet. 17-12 18-80 17-60 1816 Neaps. Feet. 11-12 10-12 15-72 ;}« .•^T. LAWUK.Vf K Ksn AKV.^^VAHIATIOX.S l.\ THK TWh.-Cuncludeil. \M HkIi.HT Ani)\K n.\TiM. SpRixd |{a\(,k. ' [.i>c:ililv. Oidc. lii'licT I'oiiit \,|({. j.i jScpt U |S..))t. 27 I jOrt 10 II. W. . I,. W. : IVrigcv Apogn I'Vct. i I'Vct, Kcrt. j F(v(. I-'-'H) J 10 ' to..-,o I I4t).'i ; -0 ;iO 14!»,". 1 ♦^M"" ' li:il Aug 11 ll'liO 2-20 : U!)o : -0 ;« lo- I l-7"> I 10 10ti."> Aug. 2.") I 1040 ■ 2-7o Sppt 10 I n:;.-> : 0()0 ' 10-7.') ; M'pt. 2.J. .^ ii 70 , 2-.",0 I i j 1 i I I ! Moan.j 10-40 DitTci rncf. reel. 4 45 j 4 -.5.5 i 4-90 .Mf.an Sj)riiigs. 1-CC't. 4(a I 12 •70 7nr, 7-20 :{ (X) ;iio :i-22 10 so .!> .Ktual as the s:imc result i.obtiunoil from tho part of tlie s(.:i.son at the two nlu-o nne,nr W ",r ""t''''-\''"" '" "" 'l'^'"'"" "f ""- ^'^'•'- "'^" tw,, "Lu' ,Ts "rienauN loint. t! -i' cljuiuicls uniting agiini at (irosse Isle. GiLi- OK St. Lawkexce.— North siiohk. During the .season of 1010, siinultanoous ob.sorvations were ohtained the North Shoro of the (iulf of St. Lawrence, on an extent of MM) l)y means of a series of reftL-terinR tide gauges. As far as Harrington, the' under the immediate .sui)ervisiou of the Superintt-ndent : ami in the vi of Hello Isle .strait, tliey were supervised by -Mr. H. W. Jcmes. ScK'H I.shtKls.^Thc gauge was erected at the village of Sevt tlie east .side of the hay. It was placed against an isolated erih form part of a wharf eventutilly. The Hench-mark is the to[) of the concrete foundation of the at t!ie west side of the main entrance. The tide scale at Seven set one foot lower than the scale on the wharf at Clark City, on side of the hay; the levels being carried across by m(>asureincn's surface taken simultaneously. I'ench-iiiark on the church, a^^ iic.-.ciibed Reference point on top of crib used for setting scale; at 15-25 above zero of scale at Clark (Mty wharf, by water transfer . Jlighest High Water in the season of 1910, on July 7 and October 21 II Islan int(-ii( new el Island the op to the F.lr feet uncludeil. .Mean Uwdi:. S|)rillgs. .\(';i]is IVit. Icct, i-j-7(i ; lOSO must be arccptoii two pla<-os, wliirh > cliumiils abiivc :)l)t:iiiie(l aloiifi of 490 milos, toil, they wcir n tlic vi'''>).iv (ii I. "-hinds, oil I), iiit(i)(lo(l to new chiii-fli, n Islands wa- 1 the oppositi' ■ to the water lOIi-vatiu:!. ... 122-47 feet ll(J-2:. li;jti() T ;{7 Avernjje level of Ilinh Water, at eight Spring tides during tiie season, from July to October 1 12-92 Average level of Low Water, at the eight Spring tides during the season . . 10.'} Otj Low -water datum adopted 102-40 Lov ( st Low Water in the season of 1910, on Uctober 21 101 - 90 Zero of seale on Clarke City wharf 101 00 Zero of tide seale at Seven Islands, set one foot lower than the scale at that wharf 100-00 A7//.S bay. — Near the west enil of Antieosti island; and the terminus of the railway huilt by the Menier company. The datum for this railway is the level of High Water; and as this important datum already existed, the elevation of 100-00 feet was taken for it, to keep the tide levels in harmony with the railway levels. For convenience, the tide scale was set with an even foot (8 feet on the - 17 ,. Highest High Water in the .season of 1910, on .\ugust 101 • 1,") Average level of High Water, at seven .'^i)ring tiiles during the seast.n from July to October l()(l-.")2 (.\lthough this is not an even number of Si)ring fide-, the value is balanced because there is no semi-monthly ineciuality in July.) High-water level adopted as the datum for the .\nticosti Railway . U)0-00 .VveraP"- ' lof Low Water, at the seven Sjjring tides during the season . 93-80 Low-% ■ um ailopted. 93 - 30 Lowest V'aters during the observations of 1910, on .'September 19 ;..iii Octol)er 2 93-00 Lowest Low Water in May and .lime, from comparison with the record of a Pressure gauge j)lace(l ;it the wharf by the .Menier company 92 - 9.'j Z'ro of tide scale, set as exj)lained 92-00 Mingan. — The registering gauge was placed at th(! end of a boat wharf Iniilt with trestles which are removed in winter. The wharf barely reached to Low Wate- d on August IG it was extended and the gauge moved far enough out to record all low waters. No permanent Bench-mark was placed here, as the country i.s sandy and there are no masonry buildings. The elevation 100-00 feet was adopted as extreme High Water; and 8 feet on the tide scale corresponded with this. On .\tigust 16 the scale when moved out, was set exactly two feet lower to main- tain the continuity of the levels; and 10 feet on the scale thus corresponded with elevation 100-00. This change is allowed for in the reductions. HiRhost HiKh Wator in the ,ea.son of 1910, ou , ulv 4 ""Z ^oxt highost on Octobor 21 " ' Lowest Low Water in the season of 1010, on ^ )ctober 20.. .'.'.'.'.'.'.',',][] "j nlaoe?^" The^'n"'-?'^'"';' ''^ V^"-''"i't wharf here, at w).i<.h the gauge placed The Bench-mark used for reference in the tide levels is a fx i spike dnvenhor.ontai;y into a wharf post, on the east sid Tf the wh r aid 1 r T V- V'' "''•■*^' '^ ^''^•^ '-^ ^-"^ ''•'"- the slope o the he« and the sp.ke is marked with a broad arrow cut on the timber. Cap of wharf, above the Bench-mark . . . ''''"'' Cap of wharf at the site of the gauge Elevation of Bench-mark, as described. !"' Exceptional High Waters after the gauge was discontinue.!, from scale readmgs taken by the observer: on November 7, l.'iioO "et on scale^and on December 2, 12.50 feet. Elevation, November 7 OS Highest H.gh Waters recorded by the tide gau.e during t^,^™ '' from July to October, 1910, on .July 8 ard October 20 07 Average eve of High Water, at eight Spring tides during the season % t:::z::7t^:^ -' ^" -^^ ^-- ^-^ •-- ^- — -• Wst Low Water in the season of 1910, on September 19 ... It Nex lowest on October 20; for comparison with the Low Water of this date at other localities .Jf';'^^^;<'\'>^rbonr.~Th, Bench-mark is the top of a heavy eve for e'wh f^ Fr:m tr' X''''^ "'^ '"*" *"'' *^^'^"'^*" ^'' "^ '>" the l.orth si built the m north-west corner of the crib on which the main shed anla Z 6 Seirr '^ '''' ''' '"'^ ^^^ ^^ ''''—- '' ^^ « -"^^ - Exceptional Higli Water after the gauge was discontinue.!, from scale '*v-i' readmgs taken l)y the observer- on \.)ven,bpr i- « ro Highest High Wat. recorded by the.rg^:: tin;;!^::;^:; I '''' from July to Octol,er, 1910; on October 20 Elevation of Bench-mark, as described r^'J Average level of High Water at eight Spring tides during the season " "S ' L:ss:ri;ii":;£r.^^ ''- -'''' ^-- ''- ^-- ^^^ — --^ Lowest Low Water in the season o. 1910. on Julv (3 S '^ Next lowest, on October '2 ' '''^'^ 93-6 thn .^"'■"■"/"''•-The Bench-mark is the top of a I,rass bolt i. he roek bein the Boundary n.ark" at corner of lots 8 and 10 on land nian In t Ft dated at Quebec, 19 November, 1907 ' ^ ^^ ^^ ^"'""'"^ Elovatiiin. . .. 100 On •to -So , from '.(n-12 n.. 0104 . . 01 oO . .. 01-20 gauge was i a six inch 10 wharf, at >f the beach; I Klovution. 102-47 101-00 100 -GO lie an ns )n m 3f 98-40 07-60 06-80 90-43 90 00 90-05 90-10 eye for a rth side of lin shed is ches north „ Kleviition. 100-65 s . 100-60 . 100-00 99-44 1 93-82 93-50 93-45 93-60 ck, being Lemoine, 39 KIrviition. Bench-mark, as (h'scril)ed 100 00 Kxceptional Higii Water of 1908, February 2. during a southeast gale luid snow storm; lieight reached by this tide, from the mean eh'vation of two jwints marked at tlie time 95-75 Highot High Water in the season of 1910, on October 20 93-45 Average level of High Water, at six Spring tides during the season, from August to October 02 - 63 Average level of I,ow Water, at tiie six Spring tides during the season . 8(i-4t) Low-water datum adopted 86-10 Lowest Low Water in tiie seascm of 1910; on October 22 86-05 Bonne Espemncr. — Tlie observations here extended only from the middle of July to the beginning of Septeml)er; so that the extreme tin. Bench-mark, as descril)ed 100-00 Highest High Water in the season of 1010, on October 20 99-81) Average level of High Water, at eight Spring tides during the .season. from July to October 98-90 Average level of Low Water, at the eight Spring tides during the season 92-79 Low-water datum adopted 92-50 Lowest Low Water in the season of 1910, on October 21 92-25 Summary Jar the Xortli shore, (lulf of St. Lawrence. — In the ta!,. ')elow, the extreme difference of leve. .i from the lowest observed to the highest at different dates (luring the season, but omitting exceptional tides not in the period of simult.'ineous observations or in other years. The rise of -Spring tides is from the Low-water datum to average High Water at Springs. The datum as adopted along this shore is from 0-27 to 0-66 foot below average Low Water i 40 at Sprii.Ks us will 1„. s,.,.,i in tl... ..Icvutj.,,,. «iv..n; tliis inarKi.i Immuk i-i ..-. portion to the total rauRo of the tide. J.oculifv. S«vcn Islands villaKr I'lli.H Hay, Aiiti^'osii .MiiiKHii! Kskiiiid Point Nata.slikwan IlarrinKlim Honnc KniKTancc* r >iV.t a (14 I ■.■.•.,( II JO liJO 41 ImM'd. are at'i'iudinKly from 18'.)8 onward. In the last four years, from WHA to 1917, the settlement has been inly ()-(M foot, which ean readily he iilioweil fur in the reductions. Tiie oriRinal Beneh-mark, to whi; h the elevation 1(M)()() feet was >:ivide of a bronzi' bolt >et Ih!' i- zontally into the edge ot a small reef of rock, at 7S feet due south from the south- east corner of the crib-work of the tide gauge. It was found in KM).") that a Hench-mark had been i)laced on the wi -t -idc of Forteuu bay by Cajitain W. 1". .Maxwell. H.X.. in 1S!U), during the -urvey- for the revised chart of IJelle Isle strait. It is a broad arrow cut on a \(rtic;il face of red granite rock, facing the west, in the vicinity of the High-wat. r mark: at 410 paces north-eastward from tiie tide gauge. The ,\dmiralty Low-water datum is defined as 8-00 feet below this Bench-mark. The Tiilal .-^urviy datum is in close agreement with this. i:iiv:ltif,!i. Surface of plate on pillar of dipleidoscope; originally taken as IDOOn. Elevation in June, 1017 lOtt li;; Floor of tide house, on th> crib-work \>2-2\ -Vdmiralty Bench-mark, as described S,H-(i7 Tidal Survey Bench-mark, the ujiper side of horizontal bolt in reef, a< described Mil'.t Mean Soa level, as -7!> Low-water datum, to which the tidal rec(.i(l from 18f)S to 1917 i- accurately reduced SI Oi) iThe Admiralty Low-water datum i> practically the same; as 8 feet below the Admiralty Bench-mark makes its elevation S0-97j. Exceptional I ow Water, tm August 2. 1894 M):i7 The values of Mean Sea level in the successive years are given below, a~ heights above the Low-water datum at elevation 81 00: — i,,.i. One year, from October 1898 to October 1899 2 0ti_> October 1899 to October 1900 2-701 October 1900 to October 1901 2-8GO September 1902 to September 1903 2-873 September 1903 to September 1904 2 8!."> Mean height above Low-water datum 2-7!t4 42 ChnUdH hny.~\t thn cantorn i-i. 1 of Hell.. UU> .Mtmit. A title nmnc ))laco(l in 18!H) at Ht-iili-y harlxmr, wliich opens off tlii^ hay, to ohtain the of the '.pen Atlantic at the eastern end of Helle Isle strait. The ol>servu were primarily intended for time comparisons with Forteau hay, to deter the difference in the time of Flinh and Low Water on a run of (K) mili-s froni end of the strait to the other; and for time correlations with otiier prin staticms. The ohservations were from July 24 to Octoher i:}. There was no IJench-mark estal)Iished here; hut only a mark (m the at the level of 4 feet (m the lule scale, to insure its not heiuK d* i)laced in he The tidal record ohtained will afford the rise at Spring and l\eap tides a average Low Water, or any other data th.at may i)e desired, if further inve ations are made in this region. (^HALEin Bay. Karly tidal ohservations were ohtaines during the season. from July to Octol)er jj; Approximate Mean Sea level, determined from two lunar months as 2-")() and 2-37 feet respectively, ahove tlie Low-Wiiter datum. Mean, 2-43 feet 8^ Average level of Low Water, .at the eight Si)riiig ti KiiUKo wui4 itaiii tli(> ti(l(> iilwcrviitidiii* to ili'tiTiiiino ili'H from one liiT principal L on the rock •c(i in height. » tides above her investig- it, whicli was nd the infln- is hay and in iieous ohser- at IJathurst and XT' "ou, •rtically into •f. The l)olt ,I)()Ht 35 feet below. The eet. Ek'Viition. ... 10()0() 8G •»).■) ion, jj 85-<)l I ■ ''* I iin. ; . .. 82-74 on. 80-32 80-31 79-70 ide . .. 79-75 « .s utilized in J 'Is; although a sharp edge, I irked with a | ivards. The J )m the west Tl i.-< Powder House is a small builtliiiK of red and grey saiid»ion of thi- Hcn, is !t-7<.> feet. I-.lcviitiun. liench-mark, as above described KM) (M) Highest High Water in the season of HUa, on October 30 •.»»■ l.'< Average level of High Water, at eight Spring ti(h>s .luring the seaM.n, fnmi July to October '•••<•'* .\verage level of Low Water, at the eight Spring tides d iring the sea-on 8ti-'.t7 Low-water datum adopted 8()-S( Lowest I "W Water in the sejtson of 1913, on November 1 80-20 Low W: of October 28 f*'>'>;"' 't V ''0 noted that the Low-watci datum here ,ind at Port Daniel, is praticii!' it the average h-vel of Low Wiitcr during the season. It is so taken to correspond with the datums at Hat hurst and (Jaracpiet on the o'herside of the bay, which were found to be at this average level. Carlelon Point, Quf.— The reference marks for levels in the observations of 1896, were the top of a pile beside the tide scale which has since been cut shorter; and the upper side of a bolt fastening a window shutter «m south end of freight shed at head of wharf, marked with a broad arrow. This bolt is al-^o gom», but the hole is available for reference. Its elevation in the Ccodetic levels of 191."), is 12-72 feet. For greater security, the elevation of three ring wharf were obtained in 1911, as given below. bolts in the cap of the described . i;i(-vutii)n. 99-35 97-14 97- 11 97-23 Reference mark; bolt of shutter of freight shed, as Top of ring bolt. First, in cai) of wharf, west side " Second, " Third. Highest High Water in the season of 1890. on November tj 93-40 Average level of High Water, at nine Spring ti(h's during the seaM.n, from ,Iiily to November 91-91 Average level of Low Water, at the nine Spring tides during the scummi 84-77 Low-water da* m adopted 84 -oO Lowest Low Waters in the season of 1890, on October 9 and November 5 83 - 80 Dalhousie.—'So observations have yet been taken here or at ('aiiii)bellton by vhe Tidal Survey, as Carleton Point was accepted as the head of C'haleur bay for purposes of tidal comparison, as explained. Some general levels for the tide, and Bench-marks, have been established by the Public Works department however; and it is their i)ractice to adopt elevation 100-00 feet for High Water, at all the ports on the coa,st of New Brunswick. This elevation is therefore retained in tiiese levels, wherever it luus been definitely established. 44 'IV Pul.lic Works HencI iiikrl: iit DiiIIkmim.- U h l.roiul jtrr.w . iit fh fop of 11 poiiif.d r(.<-k, tii'iir tin- Hl.or.' rii small i island, which cxtrnds .■iistwiird from th.^ ai>proa(li to tlir (M.vrrnin.nt ^ l.chind its head. It i.s ii copper plii({ set into the far C the rock at IK from the east side of the approach and marked . .- h.m. -«< i.xxx.iv. tide level- of the Pul.lic Works oliv Tvulioi,-, in tlir -( , - ,,| litir, ,m,| Kilt; I.'i» Water enliimry Sprinn tiiles; tleiialiiin of li.e Piil.he \\ork.,i,jbilUon. —The elevation of 10000 nhieli was Hrsf adopted for I Water. wu« fonnd to l,e too low, an.j it was rai-d to 101-00; inuKinii the ii SpruiK ranK>', 10 feet. The Hench-mark is the head of the hiKhe>t .pike in a .hister of four, di into the top of a face pile where the ca]) is notched, on tho north fuee of Hallway wharf; at 28 feet from the east end of the freight shed and 4' fast of an uiikIc in the f^ce of the wharf. The fid,, levels are as loilows- ^ " lJe.«iTi|)li(i I'. W. : (leo.|, l>'p:irt. I .\y lilt Mill, on wharf, at 1)111' (< Hiitall riM-kv rnini'iif wharf k at 110 fi't't xxx.iv. The lie siirvf\- .'iri' 1 i tcmlffic t. I Survi'v. I'rct. • I .ill .■ii;( ti'il fop Ilijih IK thi' ii'iial ' fiiiir. ihivi'n 1 face of the and 4'. f,.(.t ws : — (icil'lclir I Survey. IV,. t. ( .'i-.Vi -.•.14 tli diffcrcnt'f ope between fipbellton, is ith the Low- water ihlllllu a> ulmve »tateil. The ilrrilKinK i- to a ih'pth III' 111 f ft I'l'lnw tlii» ilatuiii, ami the Itottoni of • ilreilniil i haiiiu I i^ tint- at eiivatiuii 71 (Ml fett. Reitiijonche rirrr. -AltliiMiuh the tide hn-* a ranj{e of iliven feet at < unip- iMJlii.n, it only exteiul-* a« far a>« Moffat, about five miles above ( 'anipbellton, owinK til the slope of the river and the rapids in it. Hnlhiir.ll. — Tidal ob.serviitionn were obttiined here in the >i'a-iin uf l!ll I. ami at liiut date there was alreaily a Meneh-inark established by the (ieodetie Mirviy, and a Low-water datum estaliji^hed l>y the I'ubiie Work* department for the dreduinjt at the eiitranee to tin' harliour. Care wi therefori' taken to eorrelate t'le new observations with these levels. The Reneh-mnrk is a ehisel line on a eoppiT pluR in the north fnnit of the I'lp-t OfFK'e buildiiiK. near the north-east eorner, in the fourth courx' of masonry above the sidi-walk: and marked ( . - ii.M. !>.(((. i.xx. Its elevation in the (Ieodetie hvels is 2'i-O.") feet. The Low-water datum is defined on the plan of Hathurst iiarbuur. liy Mr. \'oli|{ny of the I'ublie Works department, as 24-80 feet below this Ucneh-mark. It is also at 7(M) feet below ordinary Ilifth Water at Sprinu tides, whieli is taken ;i< usual as elevation lOO-OO.in the I'ublie Works levels. A tide scale was placed by the Pulilie Wcrks department at the Public wliiirf. which is situated at the middle of the louK cau^-eway connect iiij? Hathurst villafce with the town. The zero of this scale rei>resents the Low-water datum; but it was found in the Tidal Survey levels of l!tl4, to be O-OS foot below datum. In the tidal oliservatioiis, which were taken at Hathurst village, the tide scale was set for convenience at one foot lower than this; ;ind the Low -water datum was thus at lOS on the scale. The tide levels when reduced to the same .-tandarii, are as follows: — I'ilcvatioit, Hciich-mark v.rvc.i.w. on Post (Iffiee buihlinjt 117-8() Lxceptional Hinh Water during a gale on November 20, 1014; reached lloO on Public Works scale 104-40 lllRhest High Water as recorded on tlie tide KaUKc in the season of HM I, on October 22 100- 70 llinh Water ordinary SpritiK tides (P.W. dept.) 100 (Hi .Vverage level of High Water at nine Spring tides during the sea>nu of l',)14, from June to October ".t'.Mil .\verage level of Low Water at the nine Spring tides during the season !)1J 27 Low-water datum, as above descrilied, ami adopted for the dredging oj)erations. ., !i:i-00 Zero of Pulilic Works scale at the Puitlic wharf, from levels of 1014 ... 02!>2 Level taken as Extreme Low Water, at 3 00 in the (ieodetie levels . 02 ■ 7.'i Lowest Low Water as recurdcd on the tide gauge in th(> season of 1014, on .July S 02-70 Hottom of dredged channel, entrance to Hathurst harbour, at 17 feet below datum 7t(-00 Caraquii. — -There is some uncertamty in the levels ht-re, because of the disturbance of the original Hench-mark. A high bank runs ahmg the shore l)ehind the wharf, which is reached by a curved approach; and the original 4(i H. ut 111.. li..jul of til.' vimrf. Til.' fin.il vi»liii-« ..f tlu' l.-vcN «-. \wrv th.-n, arc «'l.m...f that ran I..' arriv.'.l at, when chiTk.'.! with tlu- .jiita in tli.. DiMri.t of of th.' Pul)lir Work- .l.-partni.-n* nt Chatliani. Any oiit^laii.liiiK uii.'.-rtaiii! ill til.- oliliT I.vcIj* .1.1 not iiowivfr .•x.-c.-.i ()().•> or ()• 12 of u foot. In tin- M'nson .if 10i:{. wh.n ..l..s.'rviiti..iiH w.-rc tak.n l.v tli.- Ti.lal Siirv li n.w B.'n.-li-niark wa« c-.taMioh..,!, to whi.-li tlu- ti.lr levi'l^ of that M-aMin rcf.Tr.'.l. This H.-nch-mark is on a rocky p.iint \.hicli stan.!- aliov.- th.- st^ bank Ix-hinil th.- li.-a.h, at th.- ( iov.-rnin.-iit wharf. It is a horizontal km. mark..! with a hroa.l arrow. <-ut ..n the fa.-.- of this r-ik. From a point on Ilijih-watir mark on tin- shore, whi.-h i.s in iin.- with th.- straiRht part of the wli on the ea..t ^i.lo. it is l-KI fe.-t w.-stwar.l to the l.lulT on whi.h the ll.-iu-li-m. ix cut, i:ii-vut Jiench-nmrk on r.iik, as .les.-rilxil i-i., Top of !..)lt throunh cap in apprimi h to wharf, us.-.l as Fuhli.- Works Hench-niark 'lop of liolt throuuh i-Bp in apjiroach, useil as C'.codetie B.-rK-h-nmrk (lifTerent from the above ( Ji'iicral level of flooriiiK of wharf "nt the sh..re end " us.-.l for reference in the f;.-o.|,-tic levels. Klevuti.in. (i.-o.l.-tic s. li.-x, 9 17 Hitth.-st HiKli Water in the s.-.-iKon of H)13, on July 7 i(K) Next lii»(h.-st, .m October ;}0 and 31 " ....... MH) Hiuli Wat .-r ordinary Spring tide.s. (P W. d.-partment.) km) AveraRc l.v.-l of High VVat.-r at .-ijfht Spring ti.les .lurinR th.- season of HM3, from July to October Low Wat.-r ordinnry SjjrinR tides, Public W.irks department: defined MS 12 -.jO feet below the bolt us.-d jis a Bench-murk. Adopted as Low-wat.r datum by the Tidal Survey AveniKc level of L.iw Water at the .-ight Spring tides during the sea.son Lowest Low Wat.-r during the sicason of 1013, fr.im July to Oetob.T; on Oetob.-r 2.S Zero of tide .scale pla.-.-d l.y (Jeodetic survey at head of wharf; at i:{-4(i feet below their Bench-mnrk f,2 Zero of this scale, at* found in l!tl3 Extreme Low Water of November 1, 1913 100 • 1 (».-)• no- 94- 93- 93- 92-! 92-! I lari bv 1 Th(- tide at Cara.tjet is chnract.-rized by the uniisiiMl feature of diurnal ine.iuality at High Water, whereas Low Water is little aff.-cte. The semi-monthly inequality, or diflference in the range at i)erige(- .-md apogc IS much le.sH. The sea.son of 1913. afTord.-d a good opportunity to d.-t.-rmii thc^r- m^q^a!ifit•^; :^^ the nio.in wa.-; at it.-, ina.xiiiujm declination at the Sprnii m July and at the- end of October, and perigee was at the Springs in Augiwt ai September. A digest of the levels at Si)ring tides .luring the se.ison, aflfor. the folhnving result.s: — m 17 'ftllril t\Ut\ 'lliN of IioIIh li«'r<> in ^ liiiiK curviil iif tlir "Ciilc It'll, lire Mir i»tri(t fiflico rirtTtiiiiitii'.'* ilitl Siirvi'v, xi'iisiin lire ■f the .sj('f|i nttil KroDVc Kiint on tlic pf the wharf l-iit'li-iimrk Kli'viition. i;i2 ()() 111 KM! •.•)() I 00- 45 10.V32 100-40 l(K)-2"i 100 00 9<)(J2 •(t IS !t4()<) (W-82 r; '.KMO (i f>2-<)!» !}2i»2 • 92' 90 ..f :i lurge •t(v il i.y it. l(i a})oK('(\ (1. ttTmiiif Il(> Springs ugiist ami m, affords Diuniiil iiii(|ii:»lil.v in lli«li Waiir; nuati value a-< drtirmitiol in July I)iiiriial in<i tnlxT Sprinit raimi' with moon at I'crii:'"' True imaii SpriiiK riin({<', iluriiiK tl"' -n at Ai)«i(i:t*i' 2 IN) U IH .'i»»2 4 C.T 4 i:i In thi' ranKf". tin' 'liurnal in«"«|U»li«y *" 'limim*'''! '" uivf a In nipari-oii. It i, to l.f m.t.'.l that thf diurnal inr.|uality in tin' llitfli Wat.r level i^ ti2 per rent, or nearly two-thirds, of the in>an Sprinn raiiRe; ami aUo that it is nearly d.aiMe of the semi-monthly ine(|ualily. Al-o, in the tide levels, th.' averanes for HiKh Water and Low Water are the art.ial av.rane- without distinetiou of these eaUses, whiell as ill them. MlllAMI.IU HaV AM) SorlllWAKK. From a tidal point of vii w, tlii» region may lie taken to include the western rml of Northumlierland strait, as far as Cape Tormentine. The ti.ie is hen- charae.erized I.y a strongly marked diurnal ine(|tialily. In th.' early invotitta- tions, a ti(U- n-MifH' was estiil.lished in IS'.Hi, at Lower Neuua.'; in the en.leavour tool.tain the tide on the western side oftheCulfof St. Lawrenee, a.-m'artoihe open as shelter eould lie olifaiiied. Loinr \egunc.~-ln the plans for ilredtfinii in the Pul.lic Works (h'partment, the L(.w-water datum was altered by two fe.t I.etween P.HW and 190.-.; and although the original datum may have 1 u hinh, thi.s liirge alteration is too much. Also, the rise of :. fe.t at Sprin-j; tich^- is more than em.unh, as 4', feet corrcsiM.nd.s Letter with the tidal oliM'rvations. The Admiralty Low-water datum f(.r Miramichi l.ay was estal.lished at I'ortaKe island, near the main entrance through the ihaiii ..f islands. In these levels, care has l.cen taken to l.riiiK the datum els.where in the liay into relation with this, with allowame for the difference in the ranjfe of the tide. Also, in the Pul.lic Works levels, the el.'vatioii of llii;li Water is taken as lOOlM) feet throtiKh- oul; and consequently any alteration of the ri- iiKhthouse, at the h'vel of the plank i.latform aroun-l it. The elevation of this Bench-mark is Kiven as ai.i)n.ximately .■.:{() feet, ill the (.Jeodetic levels. The lighthouse is supiiorted on four main cervations were taken and 1903 and 190,'), the dates of the I'ublii' Works levels. KU'Viition. Reneh-mark im lipht house, as described 102-8/ Highest High Water in the season of 189(). on October 1 100-70 Ilich Water ordinarv Spring tides, adopted as basis of Public Works •^ , , .IB 100-00 levels 4S Avcrago level of High Water at seven SpriiiR tides wliieh were iiii(listurl)C08, was lost by the undermining of the cliff which fell away. The later Beii marks were correlated with the tide levels by means of the best existing refere marks, such as the zero of a tide scale and the surface of the wharf floori and they may be accepted as practically accurate throughout. The Public Works Bench-mark is the end of an iron tube set vertici in a concrete block, at the top of the bank, at 85 feet west of the Oak Po wharf. The Geodetic Bench-mark is a copper bolt set vertically into a large imbedi granite boulder, in front of the fish shed on the shore road at the head of i wharf; and marked c— n.M.— .m.icc.xxii. Its elevaticm in the Ccodetic lev is 17-77 feet. fieodetic Bench-mark, as described Public Works Bench-mark, as descril)ed Wharf flooring, at shore end of wharf Highest High Water in the season of 1908, on October .30 Xext highest, on July 15 H.gh Water ordinary Spring tides (P. W. dept.) .Vvenige level of High Water at ten Spring tides during the season of 190S, from June to October -Vverage level of Low Water at the ten Spring tides during the season. . Low-watrr datum as adopted Lowest Low Water in the season of l!t08, on October 14 Next lowest, on June 18 Elovat 114- 112- 103- 101- 100- KM)- m- 94- 93- Clialhaw. —The LoAv-water ilatuin as established here hv tlie Public Wor department, and the rise of G feet at Sjjring tides, are both accepted as in acco with the Tidal Survey observations, during two sea.sons. The Public Works Bench-mark is the surface of the stone door sill at tl back entrance to the wing of the Post Office building, facing the river; the poii used as a Bench-mark being at its w(!st end. The Cieodetic Bench-mark is a chis<.l line on a copper plug set horizontal into the masonry of this wing of the Post Office, on its east side, above tlie secoi: basement window from the north end. It is marked (.■.--!!.«.— M.fccr.xn and its elevation in the Geodetic levels is 10-23 feet. irl)C(l, <»9S0 J 95-74 I . .. Oo-riO 94-90 ] to represent )m a careful a consistent (ondinR to a l il Survey in | later Bench- i ng reference ' irf flooring. J t vertically \ Oak Point | ;e imbedded i head of the | idetic levels EInvation. . . 114-38 . 112-24 . . 103-28 . . 101-00 . . 100-3:) KM) -00 of 90 -32 94-53 04-.-)() 93-30 93- 90 )Iii' Works s in accorii sill at thf ; the point )rizontally the second .crrr.xiii 49 £lcviitii)ii. Public Works Bench-mark, as described 107-14 (Jeodetic Bench-mark, as described 100 -50 Extreme High Water during a gale on November 20, 1914 101 ■'^^i Kxceptional Higli Water on December 14, 1914; from reading on tide scale 101-10 High Water ordinary Spring tides (P.W. dept.) 100-00 bow Water ordinary Spring tides (P.W. dept.) 94-00 Miramichi river. — In 1903, ob.servations were taken as readings on a scries of tide scales along the Miramichi river, by Mr. G. Stead, District Engineer of Public V. ' i. These observations were taken at Loggieville below Chatham, at Nelson op site Newcastle, and at Millerton and Cassilis. They have proved valuabh' as a basis for tidal differences by which the time of the tide is known with reference to the Tide Tables. The zeros of these scales were referred to the level of the cap of the wharves at which they were placed, or to other reference marks. In the Miramichi, the tide runs up both branches of the river for a distance of 19 miles above Chatham; and it ends at rapids in these branches, at which it still has a rise of two feet. Point Sapin. — This is at ten miles south of Point Escuminac, at the mouth of Miramichi bay. A breakwater in the form of an L has been built here in recent years, at which the tide gauge was placed. 1 1 1914, simultaneous observa- tions were obtained here, and at Richibucto and Shediac. The rise of 5 feet at Spring tides, as adopted by the Public Works depart- ment, was found to be correct, but the actual elevation of both High and Low Water was higher than it should be. As the Low-water datum at Richibucto, proved satisfactory, a series of simultaneous comparisons was made i)etween the two places at all the Spring tides during the season from June to September, by which it was ascertained that the datum at Point Sapin was too high by 1 -.'tO feet. Both High antl Low Water req\iired to be lowered by this amount: and on consultaticm with the District office of Public Works, it was decided to increase the elevation of the Bench-mark by l-,50 feet which would have tlio desired effect and would also retain the elevation of 100-00 for High Water, and O.l-tK) for Low Water as before. The difficulty of determining such levels from a short series of ofjservations, when works of construction are begun, is very considerable on such a coast where the diurnal inequality is .so large; but in the Tidal Survey observations, the reductions are made at the end of the season, wlien tlie data available are coniplcte. The Public Works Bench-mark is the top of a drift f)<)lt at tlie side of the shore roaii, on a line with the centre of the Breakwater, at 56 feet from its shore end. The ctiange in its elevation for tlie reasons exjjlained, was from 115-55 1o 117-05 feet. A new I?ench-niark was established by the Tidal Survey on the masonry foundaticni of the lighthouse; a chiselled step marked with a broad arrow below il, ;U the middle of the east siite of the lighthouse, und 7 inches aljove the groumi. 28186—4 I 50 Public Works Bench-mark, as described Tidal Survey Bench-mark on lighthouse Highest High Water in the season of 1914, on October 22 High Water ordinary Spring tides (P.W. dept.) Average level of High Water at nine Spring tides during the season of 1914, from June to October Average level of Low Water at the nine Spring tides during the season . . Low Water ordinary Spring tides, at 5 feet below High Water; adopted as datum Lowest Low Water in the season of 1914, on October 24 Elpvation. 11705 116-88 100-50 100-00 99-58 95-55 95-00 94-70 Richibucto. — The tide gauge was situated at the Breakwater at the north beach. The Life Saving station is behind it. As there is no masonry on which a Bench-mark can be placed, three reference points were established for security, as follows: — (1) Public Works Bench-mark; a spike in top of pile, in the south-west row, at 70 feet from north-west end of the extension of 1910; which extends south-eastward from the north pier. (2) Reference point on floor of the Coxswain's house at Life Saving station; the surface of the hardwood floor just inside of door jamb. (3) A spike in top of pile, near the tide gauge co. i as placed in 1914. EU'vation. No. 1 . Public Works Bench-mark 108-10 No. 2. Surface of floor as described 108-07 No. 3. Spike at tide gauge 106-59 Highest High Water in che sea.son of 1914, on September 26 101-10 Next highest, on October 22 (approximate) 100-90 High Water ordinary Spring tides (P.W. dept.) 100-00 Average level of High Water at nine Spring tides during the season of 1914. from .luly to October 09-81 Average level of Low Water at the nine Spring tides during the season 96-41 Low Water datum of the Pulilie Works department, adopted by the Tidal Survey 96.00 Lowest Low Water in the seasim of 1914. an October 24 95.70 Bottom of tiredged channel, at 13 feet below datum 83-00 Sfifdiac bfji/.— The tide gauge was placed at Point du CliC-ne, in a basin near the Breakwater. The original Public Works Bench-m:irk at the outer end of the breakwater is now destroyed; but fortunately its elevation was obtained by tlie C.eodetic survey. Tlie dift'erenee l)etween the elevations of the fJf'odetic smvey and the original constructiim levels here, was thus found to be 98-64 feet, which enables the Oeodetic Bench-mark to be used for reference in the Public Works levels. The Ceodetic Bench-mark is on tiie Intercolonial railway round-house at Point du Ciiene; a chisel line on a coiiper bolt set horizontally into fourth cut stone above the ground, on south side of entrance to the round-house; and marked c— b.m.— m.cccc.lxxiv. Its Geodetic elevation is 13-87 feet, and 51 consequently its elevation in the Public Works series is 112ol to accord with the difference above indicated. A reference point was also placed by the Tidal Survey near the site of the tide gauge of 1914; a railway spike driven vertically into the top of first mooring post on south side of berthing space between the two projections of the wharf. Klfviition. Bench-mark on Round house 1 12-51 Reference point on mooring post 109 • 12 Wharf floor, at site of the gauge 106-69 Highest High Water in the season of 1914, on October 22 101-55 Average level of High Water at nine Spring tides during the season of 1914, from July to October 100-48 ' 'gh Water ordinary Spring tides (P.W. dept.) 100-00 Average level of Low Water at the nine Spring tides during the season . . 96 - 28 Lowest Spring tide in autumn, on Octol)er 21 96-12 Low-water datum of the Public Works department, adopted by the Tidal Survey 96-00 Lowest Low Water in the season of 1914, on August 5 95-65 Level taken in Geodetic survey as Extreme Low Water (Geodetic elevation,— 3-00) 95-64 Characteristics of the tide. — Throughout th ^ south-western side of the Gulf of St. Lawrence, the tide is characterized by a large diurnal inequality, which becomes extreme in the water area south of a line joining Point Escuminac ea with the North Point of Prince Edward island and extending to Cape Tormentine. 1-9 This may be considered as the western end of Northumberland strait. It is so dominant a feature in this area, that at Richibucto and Shediac, when the declination of the moon is at all high, north or south of the equator, the tide has a pronounced range once oidy in the day. An inversion of the inequality also occurs between these two i)la('is; for at Richibucto, it is the rise once a day that is pronounced, and the other tides remain near the Low-water level; while in Shediac bay the fall is pronounced, with little variation from the High- water level on the other tides. These features of the tide occur when(>ver the moon is in high declination. The large diurnal inequality in the High-water level at Richibucto is thus similar to Garaquct in the mouth of Chaleur bay, to the north; whereas the largo (iiunial inequality at Low Water is the feature of the tide in tiie central part of Northumberland strait to the eastward. It appears to be in the area under consideration that this main inversion takes place therefore. When the inequality is greatest, at the moon's maximum declination north or south of the (-([uator, the tide becomes diurnal; and when there is thus only one High Water and one Low Water in the day, the ine(iuality cannot lie expressed as a dilTerence in level between successive tides. The greatest amount of inequality under extreme conditions must therefore be shown by a comparison of the maximum range with the average range, as given below. 28186—41 52 ConilitionH. — Sciiwjii of 1914. 4 Kirliibiii'to bn-akwiitcr. Slii'iliiii bay. Kcft. j Ti'ot (IiP.iti'Ml raiiKf (if iliiirtial ti(l<>>i, with moon at maxiiiiiiiii (l(Mlinatitm| wnith at Spriii(t tiilcK, July 5 to S (;rra)>>i r:iiifEi> of iliurnal tidcH, with iiiihxi at iii:ixiiiiiiiii (Icclinationj norili ;!t Spring ti(lrs, July 2'J to 24 U'iO Sprinc raiiiir at IVrigpc, with in(H)n near I'liualor, ami small rciuaifiiiiKi iiio(iuality cliiiiiuatcd, Sept. 21 to 2."i i Spring r;itigo at Apogi-f-, with moon near (Miualor, ami inctiuality cliini-i iiatcd, (•(•tobcr 4 to 7 i ■.i'M) \'M) Moan Spring range. The large raiigo that is possible at tiimw, tonipaiod \vith the true niraii raii^ is tlms evident. In establishing levels, it is elear that care is required to obta the limitinn conditions; and also to observe the tides l)o*h night and day, determine inequalities, when deciding upon a Low-water datum. NouTfii'MBEnii.wD Str.\it, .\.\I) Easiwaui). As a feature of the tide, the diurnal inequality continues to be the doniina characteristic. In the central part of the strait, it chiefly affects the Lo v/ater level. At Charlottetown, the inequality between the two tides of t day may be greater than the true difference between Springs and Xeaps. Cape Tormentine.— Much trouble has been taken by this Survey and by t District Engineer of Public Works, to maintain the levels here. The origin bolt drilled into the rock, which is a .soft red sandstone, was undermined by t sea; and was re-established from reference points on the breakwater. 0th jnarks have been covered by recent works. It is unnecessary to describe the earlier marks; as it will be sufficient to say that the levels in the old observatio of 1886 and the Tidal Survey observations of 1890, have been maintained by tl vigilance until they could be connected in 1914 with the now T'Muih-mar placed here by the (ieodetic survey. All tide levels obtained i' ♦, well as in the ob.servations of recent jears, have thus become avauu. ie t important works of the ("ar Ferry to Prince Edward island. In the Public Works observations, during periods in the years 1886 to 18! the level of High Water ordinary Spring tides was taken as lOO-OO as usu and with a range of 7 feet 8 inches, the level of Low A\ ater ordinary Spri tides was 92-33 feet. This was also adopted as the Low-water datum in t Tidal Survey observations of 1896, as well as in the later observations in t seasons of 1915, 1916 and 1917. The range by which this Low-water dafinii was established, seems to ha been based on the greatest ranges observed dm-ing the later years of the ( observations. These ranges were, in 1887 on ^hiy 10, 7-67 feet; in 1888 June 25, 7-70 feet; and on September 7, 7 60 feet. The Pul)!ic Works Bench-mark of 1906, re-establishing the original o! is an iron ijolt in the rock at the shore end of the Bnuikwater on the south sii 53 Shriliiii' buy. r.rt. •jo:; 1 ST 1 It:. i .\< tliis was likely to Ix- covered liy rock cinliankrncnt for the Cur Forry works, tluf tide levels were carrifMl hy tlit^ Tidal Survey in 1 -14 to thofollowinp (ieodetie Hoiu'h-mark.s : — Xo. M.ccfc. XXXIX. In stoiK oundi'f'o.. at centre of east face of the Cape Torniontine lighthouse. (Jeodetic elevation 24-18 feet. No. M.cccc.xL. In lop course of the stone foundation of the Seaside House, on the east side wall, at 22J feet from the rear end and almost at ground h^vel. ('■(Mxletic elevation \'A-\H feet. (liHKlctic Hench-mark on lighthouso 121 Ol (Icodetie Bench-mark on Se.iside House llOOti Public ^\'orks Bench-mark: bolt in rock 104- 10 Kiooring of the breakwater. Original construction level 104 ■00 Hiirhest High Waters in the differciut years: ~ Public Works observations of 188(i. on December 14 101 -OO '' " of 1887, probably on January 20 101 05 Tidal Survey; s(!ason of liHo, on December 10 101-65 " season of ll>l(i, on December 2'> 101-05 season of 1800, on September 20 100-20 lliu'h WaKir ordinary Spring tides, as established by the Pui)lic Works department 100-(Xl Average hfvcil of High Water at 12 Spring tides during the season of 1015, from June to De(-cniber 0l)-!»2 .\verage levi^l of Low Water at the 12 Sj)ring tides during the season of 1915 02-71 Low Water ordinary Spring tides; the datum established by the P.W. (Uipartment in 1880, and adopted as datiun by the Tidal Survey. . !l2-;i.'{ Lowest Low Waters in the difTereut years: — Piiblie Work.s observations from August 1880 to February 1887; lowest on Xovend)er 20 03-10 I'liblic Works observations of 1887. from May to Decembi-r; low(!st Low Water 01-00 Tidal Surv('y observations of LHOli: lowest on September 11 and 20. . 02-50 Tidal Survey; season of 101."), on October IIJ 01-85 season of lOKi, on .luly 15 01 •;15 In the Public Works obseivations of 1887, from May to Deceiid)(u-, tin re were 17 tides which reached elevation 100 or over, and in the observations >'i 1888 from .lune to Dt'cendxM-, there were 10 of these?; but in that season Mone of the tides reached the extnMues above given. In till? Tidal Survey obs(M-vations. the tide scales were set low, in accordance «ith the usual practice, to oi)tain the (extremes; and in each season the height <•! the datum on the scale was accurately known from the levels. It is unneces- -iry ' > give the elevation of tlicMr z(m-os however, as they no longer exist; and a w. irking scale can always \w s(-t with reference to the Bench-marks. I'ort Hordcn. — Formerly, ( arleton head; the Car Ferry ttuniinal on Friiu-e Kdward island, oi)posite to Cape Tormentine. The Low-water datum here was lii^termined arbitrarily for the Car Ferry work.s; but the tidal observations I 64 since obtained show it to be in good corrospondonco with the Low-water datu at Cape Torinontine. The comparison is a.s follows, relatively to the Avcra( level of Low Water at Spring tides in 1915, from simultaneous observations i the two places: — Datum, Cape Tormcntinc, below this average level 0-38 foot. Datum, Port Borden, below this average level 0-23 foot. The Bench-mark, placed by the Car Ferry engineers in March, 1915, is tl top of a bolt set in the rock, immediately east of the point where the emban ment of blocks for the Ferry pier meets the bank. Height above Low-wat datum, 11-68 feet. Taking the Spring ris(> here as 7-50 feet, which correspon( relatively with the rise taken for Cape Tormentinc, and the elevation 100 •( for High Water as thus obtained, the tide levels are as follows: — Kit' vat ii Bench-mark, as described 104 • Highest High Water in the autunm of 1914, on October 22 101 ■'. Highest High Waters in the season of 1915, on August 18 and Novem- ber 9 100-) High Water ordinary Spring tides, at 7- 50 feet al)ove the Low-water datum 100-1 Average level of High Water at 14 Spring tides, in October 1914, and from May to November in 1915 99-! Average level of Low Water at 12 Spring tides in the same period. ... 92-' Low Water datum, at 11 -08 feet l)elow the Bench-mark 92-; Lowest Low Waters in the season of 1915, on May 16 and October 13 91-! Port Elgin. — This haibour is at the head of Baie Verte, in the mouth the Gaspereau river. The original Bench-mark here was a large stone, simiL to a boundary stone, set deeply into the ground, beside Fort Moncton; but has t)cen taken out of the ground and removed. Public Works Bench-mark.— A broad arrow cut on a masonry foundati( pillar, under the south corner of the warehouse of the Port Elgin Trading coi pany. It is cut flat, on a levelled surface on top of the pillar at its southwe side, at two feet above the ground. Geodetic Bench-mark. — A copper bolt in a foundatior. pillar of this war house, at 24 feet from its front side; marked c. — b.m. — m.cccc.xlvi. Geodel elevation, 11-59 feet. This warehouse is immediately behind the Port Elgin station building, ai its south-east side is 85 feet from the centre of the track. Elov;itii Public Works Bench-mark, as described 108 •• Geodetic Bench-mark, as described 108 -i High Water ordinary Spring tides (P. W. dept.) 100 - 1 Low Water ordinary Spring tides, the datum of the Public Works department 91 • These tide levels are correlated with Cape Tormentine, by means of t half-tide level at the two places, with allowance for the difference of ranj which is here 17 per cent greater. KU'vatitm. KMIS 101 • 2") 100 SO 10000 99- O.J 92 -lA 92-50 91- 8.') 108-41 108-38 100-00 91-00 55 Summenide, P.E.I. — A Bench-mark was established here y Commander Tooker, R.N. to define the Low-wator datum for the Admiralty survey? made under his direction previous to 1901. It is a iarne broad arrow of shoot copper placed on a pile on the east side of the Govenimmit wharf, nearly abreast of the lighthouse. For greater permanence it was decMncd advisable to connect the level of this mark with a reference point on one of the few masonry building in the town. The point thus .selected )'s a Bench-mark is at the north-east corner of Holman'.-* block; the joint between the stone foundation and fh8. A li«t of the (txtrctne tides is aloo (jivcn f«)r both piarcs, an well as the rwc'Jit determinations of >[enn Sea level, which now enable the two independent sets of elevations to be correlated. The hiffhest and lowest tides here given will therefore be limited to years in which simultaneous observations were obtained elsewhere. They also show the limitinR values which ordinary sea.soiis may afford. The tide scales used in the different soa.sons were not always ot the same level, sometimes being purposely alt(!red to obtain a better position for the tide curves on the recording instrument. But the true elevation of the zero of the scale in each season was accurately known; and all the levels are thus reduced to a consistent series of elevations, making it unnecessary to publish the various zero levels of the tide scales in the vo ronseeiitivo dilTerenetvs in lev<«l, between Hi({h Water and Low Water, to eliminate the diurnal ineipiality. For each Spring tide the Kreatest mean value of the.se two eonseeutivo ranges i.s taken; and for each Xeap tide, the least m(!an value. Tlu! final averages thu.-' obtained durinn the whole season are shown in the table Inflow. Liicalitv. I'ictou ('harlottetowii SiiiiiriitTsklc. . , Av KHAllE ItAN 1 ... ' c .Springs. Nciips. Mriin. Fcrt. Foct. Vn\. 4-27 2 14 ;i.2l 'M :j-84 .■.■:i',i 1 1 4-4S 2-8ti 3 r.7 P(T('iiil:iH'' ri'lalivily In Cliarloltrtdwii. till prr iiiii KM) It will be noticed at once ho"- small the.se true ranges of the tide? are. ccni- pared with the actual differences in h^vel that cati occur because of iiieiiuality and storm disturbance!, as shown by the tide levels which are given as elevatioi's. The great(!st individual ranges during this season, when the diurnal inecpiaiity occurred at the Springs in ()ctui)or, were as follows: At I'ictou (J •<).') feet, at ( liar- lottetovvn i)-7.') feet, ant! at Summersidc 0-60 feet. The rise of Sjmng titles above the Low-water ilaturn is frt)m 2', to 2\ feet greater than these average ranges, because of the large inetpiality at Low Water; as the datum is necessarily basetl on the lower of the twt) Lt)w Waters, fort lie reasons explainetl. Extreme tides at Pictoii and Chnrlollefo'vn. — ^lu the ft)llowing tabli' .1 extreme tides the elevations of the marketl points mentioTied, were obiaineu by instrumental levels, taken by the Tidal Survey. It is to be noted that the elevations at Pictou an i v.'harlottetown are intlepentlent of each other. 58 EXTREMR TIDES AT PICT017 AND CHARLOTTBTOW.V. Diitf nnii Di'Hrription. KIcviilioiis (>f II. \V. and L, W. Pttou. 1889. IWniliiT. Ilintiivit tiilc known iil I'iitoii. Kli.v»tiiiti ohtitinnl! from |H)iiitn indii'iitdl liy rc»i(li'iil« i lOOO. DrcfMibcr f), iliirinK h Kiiliv I'roin points m.irkrd mI llic tinii- ut I ii'liMi, and nmrkcil ut CImilollciown by llic llurlioiir iniwter.i lorn. February 3, ut noon; uoulhiT lultn. From ii point ni.iikcd inHidf! ithi'd, unancpti'il bv wiinIi of till' wnviH | Exci-ptional li'vi'l rccordrd liy rnunH'iTH of the IlillNbroiiKli bridu<' whildi tiikinK w.iinduigH in lb.' wintir of UKM, but dat.' iimiTtaiii I'robably the «aim' tidi- I 1008. January :., at ZiA't, durinu n X.K. naif. Ad n-cordcd on Tide! (laiiRi' at Cbarlottctown i SaiiiP tide at rictoii, said to be i\ iiiclifs hiclicr than in Diiiuibcr, I'.MX) ' L rccnrd.-d on Tide ( thp lowest Low Wiitcr at I'lti'h S|irinK lido iliiriiiK till' wiuuinii iiiilU-uti'it. ISIMl. At ridht Spring tidi'H, July to Novfinlipr 1K07. At ti'ti SpriiiK tidi'B, July to NovrmlHT 1901. At twflvi" HpriiiK tidcn, May to (Jctobcr Low-w:iti>r diituni, iidoptiil in Janiiiiry, UK)'.', iin the uto Irvcl for till' Tide Tiibl<-« I*irtiiii. Kwt. t'liiirlotti'" iii»n. I HI-OO I HI • IS ! I Him I Fwt. 84 03 83 oa .S3 24 s:i •2i) ClIAHt-OTTETOWN, I'. E. I. (>l)st>rvati()nH wore ohtaiiicd hort* in tlu> M-asons of 1S9»>. 1(H)1 iiml l(t(W; and in ()c'tol)(>r IDO", a pcriiiunonf tide (jmiK'' was fNtabli.xhiMl, lli(M)lw<>rvatioiiH ht'inn thus Clint iiiiioiis xinco that dale. The oriuitial Honch-niark of lH!)(i had 10()(K) for it.s oli'vation, and the \ovoh were transferred to u better mark in 1001 . This new Hencli-inark is on a nia.sonry IjuiidiiiK at the south-west eorner of Kind and (inten streets; the top of the sandstone plinth at thi' eorner, where marked by an inverted broad arrow eut on the masonry above it. 'I'he Low-water datmu was adopted in li)02, at the .same time as the I'ietoii datum, as tliere explained. Elcviition. lieneh-mark of lilOl, as above described 103- 18 Cap of wharf at site of tide KatiK(< 9t)0l Exceptional Hi^h Water of February U, 190-1; highest recorded. (See details in list.) 05 -92 Hi({hcst Hiuh Water in the .season of 189(i, diirini? a storm on Novem- ber () 03 00 Highest High Wat(!r in the season of 1001, from May 30 to November 1") occurred on October 1 03-95 Average level of High Water at 24 Spring tides in each of the two complete years, 1008 and 1000 03-47 Mean Sea levc^l; from tiie hourly ordinates of the tide tluring five complete years between October 1907 and April 1913. (See details given Ixilow) 89-71 Average level of how \\'ater, at twelve Spring tides in the season of 1901 from May to October; three missing tides being interpolated to give a truer average 84-96 Low-water datum determined as explained, and adopted in 1902 84-80 Lowest Low Water recorded by the tide gauge in the season of 189tj; a number in the early jiart of the sea.sou being lost. Occurred on October 84-35 The lowest Low Waters in the .seasons of 1901 and 1903 are given in th<' list of extreme tides; the lowest being the excepiional Low Water of May 20, 1901 83 03 Zero of tide scale from 1907 to 1910, 79-99 to 79-97. As re-set in September 1910 80-00 ■ m fro,..";: trl'r' 'l' '''''''""'''r '^'•-"""««.<'- 'mv, now In...,. ...„ given. I u,lu... „ro «l„,v.. ,h., Low-wufor .lat,.,,., ivl.,,.,. js ,„ ,.|„va.io„ f >tM' year r. ■lOrlolM-r l!M)7 »(»(»ctolic'r liKW OctolMT HWW fi.(»,-tol).'r l!K«» "i-tr.l.,.r HMK) („«),.fol)(>r MMO •I'nl l!»ll »<) April l!»r.' V >ril MM2 to April MM.j A ril U}\:\ t„ \prii |,,|., M' il ll'll |(. A|>ril l!»i:> .•lint ! « hcrt ■ XI7 ■'MiH ■ urn 'ttMJ !H):{ H.-,J town w, ';i Ubln, IH M . M ovor thi nn; V)l\ ■r .l« inn wa> of MTvi. ,■ wh.-n tl... , 'ruinuK. ^vs...n, of ( l.a, io..,- n.o H ..■unito ,|..(,.r,ninHt,..n ,„- .Nfoan S..„ .v,.| now avail- .1 a. „ .... .. f„, ,|„. oxt..n,|,.,| |,.v,.|linK whirl, i. U-inK |:» feet, from the olworvatl.m.M (.f IHIMi hIkI I'MM. Thii iliffor •<- ..f level eniil.|e.| the Low-water ■ liittiiii lit Soiiii?. to Ix' correhtle.l with the new lierHli-niark-'. The resultinR tide-levels aiT an folloMs; I'ili'vtit jfin. 112 IN) I0JI2 HNI (Nl nriK'h-niaik on PohI Offiee, a.-< de«erilied Hpfcronro Hench-innrk on Railway wharf Top of riiiK liolt iwd riH woikiiiR Hoih h-niark diiiiim filwrvati.ins of l!M)3; lemovetl in allerinK iippriHuh to McLean '« wharf Kxfeptionul Hiuh \\atpr which oci urmi in the autumn of l!H » or l!»|.i, in ' ulni weathor after a !*outh-we!it italo. >,tnie tide an dej(crilM»<| at * leornetown HiKhe.Mi High W .iter in the noawm of IS.'t t. mi July to Nr.veudK'r; on NoveinlK'r l> nighe-t Hidh Water in 'ho season of lOOa, from June to (tclol.er on .Inly 27 \veraKP It'vol of Hiuh Wai^r at l« Hprinn tidew: kcvch in the soanoii of 189(1 (iner 'i Port Hood, S S. Tidal oh.servations uere oliiained here in I'H.'i, which were sinuiltaneous with Pictou and « lieticainp. The Hench-niark is on the masonry fnmidation of the l.rick cliiirch which stands on the hi^h Rround above the whii f. It is a fojectinR ledjje of the first course of masonry above the uroiind, m oi .> of tl . pair of luittres-4>s at the west corner of the ImildinK. Heiii^j so hidi il.ovi d. wnin-, its elevation is taken as 1(H) feet. l;it'\ lit ion IfiOOU 7S.8.-> •K) (i.'i 9K 9.-. 08 Mi 97 • o;} 92 ■8;i 92- M 92 m 92' if) Bench-mark, as described Higliest Hinh Water in the season of 191. "> on .September 27 Average level of High Water at twlse .< rinjt tide.s liurinR the si-asoii of 191.'), from May to Xovemiit AvoruRe level of Low Water at the tuelve Spring ti(le> during the .season Low-water datum, adopted to correspond with the datum at Souris and CicorKctown, in relation to the average level of Low Water Lowest Low Water in the .sea.son ol nM.'i, on .lime 28 7G ■ 76 12 M 72 (14 71 -fi.i Chrlirnm/). .V . ,S'.— Tidal observati- >n.s we: ,■ obtaiiiH here in 191.=i, in the bay niside of Choticamp island, know: :: Eastern harbour. The Hcnch-mark is 62 o^ It m """^ ^'^\f /'r'^f ^ '*'°'* '''"'""^^ ^''"**> °^ ♦''« Government wharf; on he masonry Mil of the basement window nearest the front of the huildini the to^Tlhe^'^'Vl'' f"* "^'" ''^ " ^^"^^ •"'^^•' •^-'^ *»>«' 'evil suX at the top of the woather slope, next the inner sill of wood. _, Elovalion. bench-mark as described 100 nn Highest HiKh Water in the season of 1915, on September 27 69-55 Average eye! of High Water at twelve Spring tides durin, the season of lOlo, from May to November. ... ,.- o^ Average level of Low Water at the twelve Spring tides during the " season " Low-water datum, adopted to correspond with the'datum at'st.'paul ^ ^^ island Lowest Low Water in the season of 1915,' on June 28. . .' . .' 63-50 Note on Low-water datum in the eastern end of Xorthnmberland strait.-In deculmg on the nlevat.on of the datum relatively to the Average level of Low ;Na er at Georgetown, Souris, Port Hoo.l, and f'hetican>p, comparison ea ons as the obsorvat.ons there are continuous. These comparisons brought o hght any variations in this average level between one season and another and .n the comparison between one of these localities and another. thedilTerence of ange was con.side.ed, with regard to the margin between Average Lrw Uater and da um. The .latum adopted for the.se lo.-aiities was thtfs maTe rSl^t^rParilnd.'"" ""' ''-' '''' ''' -^-"^ ^^^^ ^^ ^^ Phince Edward Lsland. — North coast. thi. ,„a,st n 191G, from Tignish to Xauf.age. The leading feature in the ti^io IS d.urnal inequality, which is here so highly developed that the t de omes d...n.a when the moon is at its maximum declination. At s h us thoro IS only one High Water and one Low Water in the course of the da^^ 1 is n ' "' •■?"?•'• •'''"" "^*'-''""' •■""•^''•'^ ^•'^'••■f"- •— -'-' the noon IS at it.-. in:.Nimum decimation at the Spring tides. It was -dso found be^ t. base the Average levels of High and Low Water upon thH. o ^iS and two lowest consecutive tides at the time of the Springs stone 'nl!:'T "i '"""•■ f' ;""' '""'^■- '""' "">■ '••"■'* '-* " ^■*">' -ft red san.l- s on . i he harbours and wharves arc generally a mile or two distant from t^ towns whose names they bear, and there were therefore no masonrv b.S i.K> m then- v.cn.uy. I„ ostabli..hi„, Hcch-marks, it was then.fore-best to o .,V'"'t1u e "TT "■'',"■' """" '■""" ^" *'"' '■'"•'^ "^ ^^"" •"•''-^- "- •''■I't'' P. u- L u r^ *"""'' '"'••""""'"t H'''"'!'-.narks along this coast: as anv Public W orks Hench-inarks there, an. on timberwork. a Run through the sand bar, an.l serve as wharves for loading or unlo. dZ vessels. The Public Works Bench-mark is the top of the cap 'it a "Ilelik in 63 the line of the pilinR about the middle of the run on tho northeast side, and the Low-water datum is defined as 7 feet below this Bench-mark. The new Bench-mark of 191(5, is the top of a brass bolt set vertically in a concrete column 25 feet east of the south-east corner of the lighthouse for the back range light. Elfval ion. Reference mark on the Post Office building in the town of Tignish; the top of the sandstone foundation, (on stone iioxt by one to the comer) on south side of the tower 1.5fl-65 Railway Bench-mark; the surface of the concrete sidewalk at end of track of Prince Edward isl.ind railway, main line 1.>I13 New Bench-mark, on the concrete colunm at the harbour 100- 00 Surface of cap, at the head of the breakwater which extends from tlu; north-east side of the Run 100-35 Flooring, at head of breakwater 99- ((8 Public Works Bench-mark, as descril)ed 98-41 Extreme High Water of November 20, 1914; from its level on the side of the lighthouse and on a neighboring building. Approximately . 99-50 Highest High Water in the season of 191(>, on .July 14 9(M5 Average level of High Water at eight Spring tides during the sea.son of 1916, from June to October 95-03 Average level of Low Water at the eight Spring tides during the season 91-75 Low-w;.ter datum of Public Works department 91-41 Lowest Low Water in the season of 1910, on September 11 90-90 Alberton. — The Public Works Bench-mark was the top of a comer pile at the end of the Railway wharf; but it has settlc(. -eriously, probably more than two feet. The Low-water datum was therefore re-determined from the tidal observations. The tide gauge was placed at the Government wharf, the .second from the Railway whaif. The new Bench-mark of 1910, is the top of a bra.ss bolt .set vertically in a concrete column at the intersection of the Railway right-of-way and the inner side of the shore road; opposite the shore end of the Railway wharf. lOlovat i(»n. Tidal Survey Ben<-li-mark, on com-rete column 1(10 -00 ("ap of wharf over tide .scale of I!»l() 9;j-92 Extreme High Water of November 1914; from mark pointed out by residents. .Vpproxiniately <»l (iO Highest High AVater in the season of HtKJ, Low-water datum, as determiiuMl i)y the Tidal Survey to accord with the others along this shon- S5- 13 Lowest Low AVater in tlie season of lOKi. on .July 14 S4-70 The Public AA'orks datum, if taken as 9-00 feet below tlu? i)res(;nt elevaticm of their Bench-mark, would be 2] feet lower than the tlatum as here given. 64 As it was no doubt in accord with Low Water originally, the settlement of th« noiich-maik must have been two feet at least. Mnlpeque, P.E.I. — The tide gauge was placed at the pier recently built in front of the village of Malpequo. It ia known as Kicr's Shore pier, situateii in March Water, a sheltered area 7 miles inside the eastern entrance of Kichmon( bay. The dredged channel which leads to the pier, will have a depth of 10 feet below Low Water. The Hench-mark of the Public Works department, is the top of the caj) at the end of the pier near the south-east comer. It had been found difficult, with this type of tide, to decide upon a .satisfactory datum for the dredging: but after obtaining the tidal observations of 191G, the question was discussed with the District Enghieer of Public Works at C'harlottetown. It was decided to place it one foot lower than the Low-water datum as here adopted by the Tidal Survey; and it is accordingly defined as at 9- 10 feet below the Public Workx Bench-mark. The new Bench-mark established, is the top of a brass bolt set vertically in a concrete column, at the corner of Dr. Kier's property, near the shore end of the pier. Elevation. Tidal Survey Bench-mark, on concrete column 100 00 Public Works Bench-mark; cap of pier in 1916 98-45 Highest High Water in the season of 1916, on July 14 95 05 Average level of High \\'ater at seven Spring tides during the season of 1916, from end of June to beginning of October 94 12 Average level of Low Water at the seven Spring tides during the season 90-62 Low-water datum, as adopted by the Tidal Survey, to accord with the others along this shore. (At 1-00 foot on the tide scale of 1916) . . 90-:r Lowest Low Water in the season of 1916, on July 14 89-80 Public Works datum for dredging; at 9-10 feet below their Bench- mark. (At zero of the tide scale of 1916) 89-35 Zero of Tide scale, at 10-65 feet below the Tidal Survey Bench-mark. 89-35 Bottom of dredged channel, at 19^ feet below the Public Works Bench- •"'•'■'^ 79-00 litLslico.- -This harbour is protected by two breakwaters, at the two side." of the entrance. The tide gauge was placed at the end of the cribwork that runs out from the front range light. It wa.s thus 1,200 feet inside the line of the breakwaters. The Public Works Bench-mark is the top of the cap at outer end of tin- northern breakwater which extends from Churchills Point. The Low-water (latum is at 8 feet below the Bench-mark; and this was accepted by the Tidal Survey. On the Public Works plans, the rise of the tide above this datum is siven as Springs, 4 feet; Neaps, 2 feet; but this was found to be too little, as the levels will show. Tlio new Bench-mark is uie upper side of a bra«s hoit set horizontally into the side of a concrete column; at 25 feet east of the front range lighthouse, ill line with its north side. 94 12 90 62 90 .T 89 SO 89 35 89 3.-. 79- 00 65 Tiilal Survey Bonch-inark; in the side of concrete column, as (loscril)e(l Public Works Bench-mark, on breakwater Extreme High Water, from mark pointed out by residents Highest High Water in the season of 1916, on ()ctol)er 14 Average level of High Water at eleven Spring tides during the season of 1916, from June to ( )ctol)er Average level of Low Water at the eleven Spring tides during the Low-water datum, Pi-blic Works department, at 800 f(!et below their Bench-mark; accepted by the Tidal Survey Lowest Low Waters in the season of 1916; on June 16 and Julv 15 Kli'Viiiion. 100-00 95-43 93-65 92-60 90-93 87-. 54 87-43 86-75 St. Peters harbour.—This harbour is protected by two short breakwaters at the entrance to the bay, extended as sand breaks. The tide gauge was placed inside the head of the west breakwater along which the fish-houses are situated. The Public Works Bench-mark is the cap on the north side of the break- water, near the shore end, opposite the fish-houses. The Low-water datum was defined as 8-51 feet below this Bench-mark; but the observations of 1916 showed this to be 0-65 too low, relatively to the others along this shore. The District office of the Public Works department preferred to alter the elevation of the Bench-mark by this amount, namely from elevation 104-51 to 103-86; in order to retain the elevations 100-00 and 96-00 for High and Low Water respectively, in their series. The Low-water datum as adopted, is therefore at 7-86 feet below this Bench-mark. The new Bench-mark is the top of a brass bolt set vertically in a concrete columr at the inner side of the sand barrier which extends inland from the breakwater; and at a distance of 312 feet west of the lighthouse. Elevaiion Tidal Survey Bench-mark, on concrete column 100-00 Public Works Bench-mark, as described 97-13 Level said by residents to be reached by extreme High Water (approx- '■nate) 9,j.„- Highest High Water in the season of 1916, on October i4 94. i.-, High Water ordinary Spring tides, of the Public Works department ; ar 4 feet above datum, and corresponding to the new elevation of 100 - 00 in their levels 93-27 Avcra-e level of High Water at ten Spring tides during the season of 1916, from June to October 92 -.58 Average level of Low Water at the ten Spring tides uuring the .season . 89 • 54 Low-water datum as determined by the Tidal Survey and adopted by the Public Works department 89-27 (This is 0-65 higher than datum formerly shown on Public Works plans, and corresponds to new elevation of 96-00 in their levels.) Lowest Low Water in the season of 1916, on July 15 stj.yj 28186—5 ()0 Sanf rage. —The. works horc con.^ist of a pair of guidp piors which form i\ " Run " th.-ough tho .saiul bar. An entrance i.s thus niaintainetl to the pond inside the l)ar. There are no Public Works levels here. This locality was selected as a tide station as beinjj the nearest availabii to the east end of Prince Edward island. Along the north coast (jenerallv the range of the tide is greatest at the west end, and decreases eastward. By having a station as far east as this, it was ascertained that the least range occurs at St. Peters, and that it increa.ses again slightly at Naufrage. The Bench-mark of 1910, is a chisel line ^2 inch deep, with a broad arrow below it, cut on the concrete foundation of tho lighthou.se on its south-west side near the west comer. Elevation. Bench-mark, as described 100 tMJ Level said by residents to be reached by extreme High AVater in storms (approximate) 57 .4q Highest High Water during the observations of 1916, up to the end of September; on August 14 55-65 Average level of High Water at six Spring tid&s during the season of 1916, from July to September 54-96 Average levrl of Low Water at the six Spring tides during the season. 51-67 Low-water datum, as adopted by the Tidal Survey 51 .30 Lowest Low AVater in the season of 1916, on July 15 50-55 Summary of Rii^f»ro if from the reach of the waves, in so exposed 51-67 " situation. When it was carrie.1 away in the storm of Februarv. 1895, it was 51-36 ^ "" "^ ^'' ^"'^'^ ''''"''•' "'k'^ ^^''*^*"'' f""" K'-'-ater seeuritv. When anv accident 50-55 I "^•■"''"■•' ♦" ♦he clock of the recording in.strument, especially if in winter an mterruption of some months might occur before the clockwork could be sent to some city for repair and be returned. A special fvpc of recordinR instru- ment was therefore designed for such i.solated localities, in which the driving clock was interchangeable with a duplicate one. There were similar difficulties at first in obtaining correct time for the observations. Becau.se of these diflScuIties, summer .stations were established on the two sides of Cabot Strait in 1901, in northern Cape Breton and near Cape Ray to see whether the reference station could not be placed on the mainland. Neither of these proved as suitable, however, since the tide is ((uiK" fret^ from local di.s- turbance at the St. Paul island station, which is within four miles of the 100- fathom line. It was also evident by that er 1898 2-436 " May 1899 to May 19(K) 2-34:{ " May 1900 to May 1901 2-339 " August 1902 to August 1903 2-260 August 1903 to August 1904 2-311 August 1904 to August 1905 2-302 December 1905 to December 1906 2-231 " December 1906 to December 1907 2-282 May 1908 to May 1909 2-387 " May 1909 to May 1910 2-431 " May 1910 to May 1911 2-46^ " May 1911 to May 1912 2-371 " May 1912 to May 1913 2-424 " May 1913 to May 1914 2-41 1 General average, giving elevation 21-93 feet for Moan Sea level 2-369 « « (i!) 49 08 37- 55 25-90 25- 75 2a G.'J 22- I (i 21-93 20-22 [ 19-5)) 19-32 18-80 18-45 16-17 Port mix linsi/iits, A'yjV/.— This Imrlxiiir is practiciilly at ('«|m« Hay, and thus ropn'sonts tho tido on tho north-east side of Cuhot strait. Tifhil observa- tions wore obtained here in 1901, from July 9 to November I. For the tide levels, the point made use of a« a Heneh-inark, is the top of an iron eyi'-bnit let into the roek, at six feet west of the north-west i-orner of K. Pike's fish store, at the head of tlie (Jovernment wliarf. Reneh-mark, iis descrilied Hinhest Hinh Water in the season of 1901, on September 30 Average level of Low Water at eight Spriiijj tit (-oast of (ape Hreton island, near the entrance to the Mras d'Or lakes. Tidid obsc-rva- tioiis wer:> obtained here in 1915, from .luly to October. The Beneh-mark is a brass bolt set vertically into a hun«^ boulder, almost buried in the sand, near the High-watermark; ;it 72 feet nort!i-v est from the shore end of th(! wharf at .Munroe (xiint. Kli'Viitiun. Bench-mark, as described 1(K)-(M) IIighe.st High Water in tho sea.son of 1915, from .luly to October; on Septend)er 27 1(10-05 Average level of High Water at six Spring tides during tlu^ season 99-01 Average level of Low Water at seven Spring tides during the season. 94-91 Lowest Low Water in tho soa.son of 1915, on October 13 94-40 Low-water datum, adopted to accord with the datum as established at Sydney, n'latively to average Low Water there 94-26 Sydney, .\.S. — Tidal observations were obtained hore for one full month in 1901, during the progress of the simultaneous series at Port aux Basque.s, Pictou, Charlottefown and Sunimerside. Further observations were obtained during the sea.son of 1915, from .July to October. In both years, the registering tide gauge was placed at the Intercolonial railway wharf at Battery Point. In 1901, a Bench-mark was establi.sh(!d on the old Court House at the corner of Charlotte and Desbarres streets, with relation to the City datum. In 1915, this Bench-mark was found to 1)0 buried under ma.sonry, as the building was being demolished, .\nother Bench-mark was therefore established on the new Court House building; a bra.ss bolt .«et horizontally into the champ- fered course of the foundation, in west face of wing on north side of tho building. The City datum was accepted for tidal purposes, to avoid introducing any new system. It is approxinuitely the level of extreme Low Water. The S elevations of both the Beucli-mark> established in 1901 and 1915, were deter- mined from City Bench-marks, in the neighborhood. In the elevat given, the City datum is taken as 1(H) (K) instead of figures as for City levels. ions Here zero; which gives the same 2-369 70 IJrv.iliDn. Boiicli-nmrk of lOlo; tint iip|HT xi,!,, of tlir l.ra^^ holt, as <|(^HiriU-i| 14077 Capof Wharf at site of tiili> jfaiiRK of 1!M)I 1I(I-»H H>15 ...'!,.,..,. ^ 110.48 FIiKh«wt IIiKh Water .hiiiriK tlu>wa«)n lu-ijilit n-ailinni, it.i ztii> imnn d with rcfcronco to a Mt-iich-niariv. When th«i tidal inviwtinations wvw Im-kimi in IS!),'>, it waN found that thnte datunis were in uxe at Halifax, which were out of ai-iord with i-arh otlifr; the Admiralty datum, tho Hoyal lindini'crs' datum, and the ("ity datum. The most important of tlu'sc- from a marine point of view is tho Admiralty Low-water datum, to which the .soundiuKs on the chart of Halifax harbour are reduced. This datum is fi.xed with referenda to a Bench-mark in the Dockyard, and it was defined by tho foUowinK note on the ciiart of Halifax harbour: " The soundin^.s are reduced to the level of Low Water ordinary Spring tides, viz., It) 1)H feet Imlow a Kench-mark cut near the soutlM-ast angle of the .Sail loft at the Dock- yard." The mark is a chisel line on the masonry with a broad arrow below it, at '.i}j feet from the south end of the east wall of the building, which is now known as No. 3 Storehouse. This datum was adopted from the outset as tin; zero level for the tidal observa- tions. The height of tlio tiile in the resulting Tide Tables is thus measured from the same plane of reference as the depths shown by the soundings. The level of the tide gauge, during the years of observation, were checked directly from the Bench-mark in the property ailjoining. and any changes in elevation at the gauge, due to .settlement or other cau.ses, have Iwen carefully allowed for. The zero of the sight gauge was kept for convenience at 1'4 feet Mow datum, 80 that any extreme tides might bo recorded on the corresponding diagram of the recording instrument; but the elevation of its zero, and the consequent reading of the datum on the scale, was at all times known to the nearest 001 of a foot, which enabled the record to be reduced to datum through- out. Relations between the datums. — The liest relation between tlu; other two datum planes was established by Mr. K. H. Keating, when City Kngineer at Halifax, from comparisons between twenty-one Bench-marks, which define the City datum and the Royal Engineers' datum respectively. The difference ijetweon them, when two except i(mal values are discarded, ranges from IGl ♦o 1-96 feet; and the average of the nineteen remaining differences is 1-81 feet. The mean value which Mr. Keating finally adopted, places the Halifax City datum at 1-85 feet below the Royal Engineers' datum. This value for the difference has been generally accepted. An endeavour made by this Survey to obtain a relation between the City datum and the Bench-mark in tho Dockyard, gave no satisfactory result. The City Bench-marks in that vicinity showed a want of agreement with each other, and no method of working out the comparisons could b<> devised to obviate the outstanding discrepancies, which ranged from four inches to a foot. The elevation of the Bench-mark in the Dockyard was given as 11 05 feet above the Royal Engineers' datum on their plans; and it was so noted also on the chart of Halifax harbour. The datum is undoubtedly intended for Mean Sea level: but when this level was correctly obtained in 1902 from the first four yeare of continuous record from the Halifax tide gauge, it was found to differ by 1-55 feet from the Royal Engineers' datum. Such an error is inadmissibly large where the range of the tide is only six feet; while the intention that the Adiiiir- w yours ctf tidal 72 .iHtn.n >houl.l rP,,r..«.nt Mnnn S,.„ lovol i. ronh. ,, J.v their .iHtum at QhHk-.. q!uZ! ''""■"'"''*""''■"•■" '"* '■'"'"•• '•" ^hown l.y »ho olovaMoim „|„.„.ly niv.n, for Th.. altrnli,,,. of tho ( "oli.n..| ( '.,i,.i,win.li..K ihn Hnv„| K„K„..H.rH wa. r.-.ll,.,| to fhw .i.Mm.pancy in nM)2, aa if «p,H.aro.l prol.al.i,, that tho .rror w«k i,, the e^vat.on of th.s indivi.hml Uench-nmrk. On invoMiKution this pn.vod to l.o the <-a.o ami ,fs true elevation is 12m f.,et,as found by .-onnoct.nK it with four othor rohal.lo Honch-.narkM an 08tftbli.h..d l.y the Hoyal K.iKin.H.r.. Thin l.rjnit. the datmn into rock! relation with M.-an S<,a l.-vH. a- now d,.tornnn..d in.lo- pendontly from .Muht complete yciurn of ohwrvation l.v tlu^ Tidal Survey rho rclationn of the various bservation Royal KiiKincers- .latum, at 12ttl f,K,t l)olow the Heneh-mark in the DfK-kyard, this Immur the Hahfax City datum, at 1-85 feet below the Hoyal Kngineers' .latum as determined by Mr. K. H. KeatinR Admiralty Low-water .latum, and Tidal Survey datum, which is the zero level of the Tide Tabh.^ ^J ^^ This value of Alean Sea level ]■■.., been a.lopte.l as datum bv the Ce.Hletie surwy, for their levels extendit.R fron. the Lower provin,...s to the St. Lawrence ami westward. The levels of the Oon.inion Observatory systen., which starte.l on«,nally fr..n. ,1.0 fr..ntier of Maine, are now connecte.l with this accu ate Ime from Halifax to Yarmouth, an.l from Halifax northwar.l T,de /«.W..~The Reneral tide hvls at Halifax, an.l the details ,.f th.- .i.-ter- n.nation of Mean Sea level, are given Ih-Iow with reference to the Adn.iraltv Low-water datum, which is taken as lOO-OO instea.l of zero to avoid negative values. The relation of this datum to the " Xverage level of Low Water" was co„.puted from the Ti.le Tables, t., ascertain the margin b.iween the two, 1" the ca..e of a well-establishe (18 ;{-i!> 102 Bench-mark in the Dockyard, as alrea.ly described . . ^' iT'oK Copingof I he Halifax Dry Dock... 110 97 Saxby tide .,f October 5, 1809. Elevation at Halifax as determined in 1870 by Mr. Keating while City Engineer; 7-90 feet above the "'•^''"^"'" 109.52 73 Highest HiKh Wafer rpfnri|p khiik<' .*), IIM) I I(K»:{,5 HigliflKt HiKh W'uU'r reconli-d iliiriiiK tlu- yciirn MMW fo HMM». <>rnirr«| Jiiiiunrv 2.'», MUKJ lOHS.'* AvoruKP lovol of HIk)) Wnfer at Spi ng tiilon; from tho hciirhlrt in tin- Ti TablcH (lurinn tlic! two roiiipli>ti> year" l!ti;{ and 1(114 KHi 2H AvprttK<' level of HiKli Water at Smp tnU's; from tho Tide Tallies (lurinK tho Nime two year«< iK.'i-.'JI Mean Sea level; from the lioiirly ordinate^ of the tide duriiiK nine eompietc yearn Ixitwecn NovemlM-r ISHo and July MMMl. iSee fietaiU ({iven ImIovn ) |(i;{-4!» Averano level of Low Water at Sprinn tides; from the Tide Table values durinn the two yearn VM'.i and Kill, nn aliove HM» .'►■1 Admiralty Low-water datum, to wliiih the tidal ohnervations were n-dueed tliroughout the years IH1».') to UMHi. Also the zero level for the height of the tide in the Tidu Tables |(N) (Ni Kxreplional Low Waters durinn the years of olisi-rvation, from 1895 to 1«ed by storm 98-82 In 1900, on July ti; not disturbed 99(H) Hill of Halifax Dry Dock. Ceoiletie Bench-mark Xo. 832, on surface of the sill. { ieodetic elevation, 20 • 99 feet below Mean 8ea level . 7t> • 50 Surface of the uranite sill of the dock. Tidal Survey determination in 1«02 7(i.49 The depth of water on the sill of tho dock at any tide, may therefore bo found by adding 23-5 feet to the height of High Water as given in the Tide Tables for Halifax. Mean Sea level at Halifax. — The dtterminations are from the hourly ordi- natcs of the tide measure of N..va Srotia ho,„ anno alrno,, ,o (•„,«, Sahlo. i. n.arly Mn,»ltan.,ouH u„h Halifax, and atH,..t h.. .am,. „, Its ranK... At Yar.nouth. th„ ti.lo i. .ii.tinctiy ol th,' l,«v of Kun.lv Iv'T/w!.',' T " 'T '■"?"""" '"""•'•*''"'"'" '^i'h «t. John. Th„ inv.,HtiKa.i«n« ran fn-.t 1m, ref,.rr,Hl to Hal.fax, whil.. from Puhnic-o westwar,] they can (^ r..f,.rro,l t,. St. .lohn. N.B. with Rroator a,.rurac.y. In rojcanl to ti.lo lov,.U. it wa« not .Imned ncce8«»ry to e.tal,li.sh B..nch- rrnrk. at .>h,.llH,rne. I arr.nKton „«.«,«,. or Pul.in.-o. At two of them, harlH,ur. h. wharv.,« an. „ p.hnR an.l are not liable, „, H,.„|„nu-„t; an.l th« zero of the tulv s,.al.. wan fix.-.! with r,.f..r..n,.., t,. th.. <•«,, of thc«o wharv.>... Affr tho ti.lil rHa',iv..rt! 'Ih'T'" '*'"^"'".'''r^ •*"■ '"'«-«•"''"• •«"•""' «as ,|,.,.i,le,| ,.,x.n. I r •" '"/^^":»K" '"^•'•> "^ '-"vv \Vat,.r at Spring ti.l..s aocordinn to the .fan, lanl ,n,.th,Kl. „n,l to .orreHjK.n.i with the Halifax .latun.. The t.de IovcIh may th.refor. U.t 1„, «iv.,n with reference to thi. dat.nn. At Clarke harW lefi i*; "".'"/""' '"""l'' "'.'"'"^ ^"'•'"' "^ »«""-''-""*rk was c.tal.liHh..d, an. tiefinite elevations ..an th.-ro bo Riven. At these l,.,.ali.ies. .-v.-n where there are no ,M.rn,anenf Bench-nmrk. the .latum hne .s rule. I on the ti.le ,lia,ran,s. There is thus a re.ord of thetiX, "low tt: '; "'" "' "'"" '"'•"""'^^' ''''' ^•'^••"•"- '" ■* consistent S; Ol i.ow-water tlatums. SMburnr.^-T\u'^ zero of the tide s.-ale was at 14- 12 feet Ik,1ow the cap of the wharf; an.l the Low-water ,latun. is at 1 -80 on the scale. Cap of wharf above Low-water .latum . .I'V„ Highest High Water in the s..ason of 1SK)2, on October 1 v iwl Average level of High Water at six Spring tides during the season of I'JUJ, from July to In-gmning .)f (ietolwr 7 01 Average l,.vel of Low Water at s.,v-,.n Spring tides during the season 0.49 Low-W!ttor d.itum a.-i adopted . . " ^1 Lowest Low Water in the .season of 1902, on July 8 (below datum) . : -O-^O Zero of the tide scale of 1902, below the datum as a.loptcd _i . 80 Hitrriiifiloii ////"■Kij/c, -Thi^ p«*«ii(jr liiv< lN>tui>«>ii ('a|N> Salili' i'liml ami thu niailllaliil. Tlif »tr»» of llin ti<|t> -tciili- wa- al \\V2 ff«M Im-Iuw llir cap iif ihr wharf: hihI ihn I-nw-watrr ilutiid* i* at I 'i'l oii llic ot ali'. Cap of wharf «tM)vc I.mv-water ve(i Spri!! II IM) II 1.-) 1 Cm I,o\v-uater ihilMiii as adoptetl l,oWe>( low Waler ill the Mia-oii of I'.HIIi, on Oetolier l> Im-Iou ilatiiiii Zeni ol rli<« till'- sc.>le UMow Hi" >l mini a"< mlopfeij ... ( I'irk-i- fiiirhiiiii-. -TWiH h, II (■our i>< in tiie iiiitiiediale vieinily of (ape Sal>le, Ihe estreiiM -outhem enil of ,\ovu Scotia. The Heiiih-iiiark of IIMC' in ihe lop oi an iron liolt drilled into tit. roek at U'.^ feet from ihe iiorllMii>t eonier of SwiiiiV vvai'hoiiwi, whiili i th' nn»st iioitherl\ of a *i I of liiiildiiiK^ thai extend to the (JoMTiiiiieiit «!iatf :!» SwiinV l'(.int, IJi'viitt.m. 1(H) (N) (>0"*i KOJMJ SO (HI 7!» 42 T!» 20 Bpiieh-mark a- dej2, on July 7 Summary of Jiine and Datum Imh —T\w followiiiK tahle is lia-eu on li- simultaneous ohservatioiis of l'.M)2, from Shelhurne to Varnioi:!-. h ■< eonneets thi? Atlanlie roast with the eiitraiiee of the Hay of Kundy :. .' iii'»> . the fojisistenry of tho Low-wuter datum throuKhout. The tiui::!h wrv.n Ihe datum and iho AveraRe level of I,ow Water is also in ko««J . ,,•.(,-,.,'. i,.,. with HalilMx, uh ^liown by its value as given in tho Halifax tide •.' ■ Lorality. Sholburnr lliirrington paAsiiitr Clarkr harlMiiir, i.'n\M' Snhlc. I'tihiiiro (ul Ia)W(T Kust I'ubnico). Yarmouth, N.S Sprinn ri.>n'. I'"rrt . 7 »1 913 10 M 1203 14'88 K.itrciiM' (lilTiTiiici' of l.v.l. I. :• ■,• I,. W . SliriiiK*. Kci'l . 8-.S0 '. I !) 70* i 1 1 :io ! i;j .t) Foot . 4!» •»» U lit 0-6-' 0-70 * The pxtn-nii' tidm of July K-erp not obtainetl hprp, and this value i.< not linn-fore truly <'uin|mnttive with tho otlior loralitics. 7() Bav Of FiNDY. (Lowfir part.) 'J'Ih' s,),,,ii.l chaiii.-tnristic ..f thn tido in this reRioi, is that it i« chieflv inHuoMco,! hy the inoo.i's disfan.-o. Tiu, variation h. rango with the nhar.Kc in tlie moon s distance from perigw* 'o apoRws is distinctly (treator than the variation from SpriiiRs to Xoaps. Tlie vahics of these variations will be Riven in a comparison of St. John with the head of the Hay of l-nndy. This type of ti as truly coiiiparativ.! as possiiile. ft is to be note.1 that where there is no permanent Ben.-h-mark, the datum line is rule.l ..n the ti.h, .liagrams. The heights an.l levels of all lidos arc thus recor.le.l with refer.n.-e to a .latum whi.h is consistent with others in the region. Loinr AV,,v< Puhnico. -Ohsi^rvtitkms were obtaine.l hero in l»o2 in the simultam-ons sera.s alr.-ady referre.1 to. from Shelburnc to Yarmouth. The zero of the tide scale was at 17-58 feet below the cap of the wharf, an.l the l.ow-water datum as determined from the observations, is at 0-40 on the scale. / ' t I e t FlTt. I ap of wiiarf above Low-water datum 17-18 Highest High Water in the season of 1902, on .July .■> 13.00 Average level of High Water at eight Spring tides .luring the .sea.s.m of lft()2, from .July to October j2.o-} Average level of Low Water at the ()2, .,11 .July 7 (below .latum) . .'. -0-20 Yurmoulh, .V ,S'.-'l'i,|al ..bservati.)ns w.-re begun hero with the simultaneous series thn.ughout the Hay of Fun.ly in June. IHUS; a.i.l it was foun.l possible to continue them until January, 1!>0.1, on a.-cotint of the mil.lne.ss of the region witlmut the complete installati.m an.l winter h-ating which are necessary at a 1 other stations. With .son... special precautions, there was a l...ss of roconi ot only one t<. 2'^ months in three of tlu, winK.rs in this peri.xl. A total of 24 months of ob.servation. .simultaneous with St. John, serv.i.1 as a basis for the .lifT<.r..n.e in the time of the ti.le; an.l from four m.mths at the four quarters of the y.-ar in I!HW, the ratio .)f the ranges was .letermine.l. The rail l.-v.-l at the railwivy crossing at the foot .,f F.)rr..-st stre.,t was originally taken as KM.tK) f.-et; but for a perman..nt Hen. h-inark in the vicinity 77 of the tiilo KiiiiKc, flio hrirk cliitiiiioy of the KoinptvilK* Liiiiild-r compiiny wsi.i selected, as it stands on a stone liase liwilt in cenicnt and tiie foundation is carried down to the rock. The point used as a Bcncli-niark is the joint hctwcon the stone foundation and the lirickwork, at the north-west corner. When it was found in 1904 that this .saw-niill was clo.si'd and tlie property niinht lie sold, the levels were carried for ({'■''fi'*"' security to the Post Office IniildiniJ. The Hcnch-tnark is on the north side of tin; liuil(Hiiu. at five- feet from the corner of Main street; a broad arrow cut on the second course of the sandstone foundation, at 2 feet 3 inches above the sidewalk. Levels were taken in 1901 and 1902, to obtain tiie relation between tho Tidal Survey levels and the Town datum in Yarmouth; and in this etideavour the Town onKincer, Mr. K. S. Matheson, auvt^ his co-operation. The compar- isons differ by about two inches, however, as shown by the two hen! Kiven. which were checked by two similar ones: — Spindle of hydrant at corner of (Miff and Main streets: elevation above Yarmouth town datum, 141-88. Tidal Survey elevation, l.lTol. DifTerence. 4-57 feot. Top of stone post at soutli-t^ast corner of L. I". Baker's ofTice, at head of tho Yarmouth Steam.ship company's wharf; elevation abov«! Yarmouth town datum, 99-54. Tidal Survey elevation, !M- 81. Difference, 4- 7;Heet. The mean difTerence is therefore 4-G.i feet, w-hich was adopted. It was possible to use an open tide .scale all the year round at Yarmouth, a.s this is the most southerly region on all the coasts of Kastc^m Canada. .MiIioukIi the scale wa.s replaced two «)r three times during the years of observation, its zero was at all times accurately known in elevation, within 0-01 of a foot. As the primarj- object of th<' ob.servatiems was to obtain time values for Tide Table purposes, the Low-water datum was not decided upon until three years of observation were availabh? as a basis. Sonif- care was also required, as the level of Low Water may differ as much as 2} ivvt at consecutive Spring tides, wlien the new and full moon hap|M>n to fall at [MTigee .-md aiMtgee. The relation of the datum to the Average level of Low Water at S|)ring tides, will b(' seen in the (ilevations here givc^n. At the ro(|Uest of the Dominion ()b.s«>rvatory, tin- value f>f Mean Sea level at Yarmouth was delerniiiied in 191 J, from the hourly ordinates of the tide during one complete year of observatiop, in 1899 to 19(K). It was foimd to l)e at 7-548 feet above the Low-water datum. This d(>terminafion, and the value at Halifax deduced from the observations th(T(v wi're utilized by the Dominion Observatory as a basis for their preci.se lev(!ls on the shore line from Halifax to Yarmouth; the levels being thus correlated at both (inds with the true mean level of the sea. In th(' tidi levels following, the extreme tides in the .seasons of 1898 and 1902 are included, for comparison with the simultaneous series at other localities in tho.se years. Kli'viitiim. Hench-niark on I'ost Office, as described IIU -89 Hench-mark on chimney of Kempt ville Lumber (-ompaiiy, as described 108 .■).'{ Kxtreme High Water; the highest recorded (m the tide g.-iuge l8feet above Low-waterda.um 82-15 Mean Low Water at Spring tides; JK,ing the average elevation through- out the three years 1901, 1902 an,l 1903, of the two low tides of the day at the Spnngs; the diurnal inequahty and the semi-monthly inequality being both eliminated. ' -.- .j^ Average level of Low Water at 24 Spring tides during the complete "" year as above, from July 1899 to July 1900; omitting two disturbed tides Low-water datum, adopted in 1905 as I'-OO foot lower than the mean ^^^^ elevation determined, in the manner explained, from the Spring tides of 1901, 1902 and 1903 ^^ j^ ^ Lowest Low Water during the simultaneous series in the season of 1902 on July 7 ' Lowest in the summer season of 1898, on July 5 74' J? Extreme Low Water during the three years 1901, 1902 and 1903 ■ occurred in 1901 on April 20 ' 73.^5 K M^'tk"'" 1- """ '."'! "* Yarmouth is 55 per cent of the rise at St. John, yi. This ratio applied to the height in the St. John Tide Tables, gives the rise above the Low-water datum at Yarmouth. WeMporl, -V.^V-This harbour lies in Grand Pa.ssage, on the north side of Bry.,r island. Tidal observations were obtained here in 1898. from J^ / to November 24. No Bench-mark was established here. The tide levels are referred there ore to the Low-water datum; which was determined relative v to .>t. Jolin as follows: — The St. John Kxtrenio Low Water as recorded in the later ohservatioii^of Deeeiiilx'r; on Pocomher li» -()•;{() Dighy.—Tu\n\ ohservatioii,- were ohfaiiicd at DiRhy pier in IS per cent greater at Digby. This value is of service, because of the connection of the provinces of New Brunswick and Nova Scotia by the ferry steatnships between the.se ports, on the opposite sides of the Bay of Fundy. 8() Ixwalitv. St. John, XB. DiKbv, N S... Sprinu ttM' nb harbour on the inner side of this islan.l. in 1898. Thi.. location, in the extreme ( anadian waters adjoining the International boun.hirv. was selected U'cause It was here that the old observations of 1845 to 1847 were obtained, durinK he oriKinal Admiralty chart surveys. This ti.lal recr.l exists; and althoi.Kh here rs no Bench-mark, the lin.itinR levels reached cat. Ih- given with reference to ttie tide scale then used, as follows:— Highest HiRh Water of 1^5 to 1W7, oc.-urre,! Januarv 27. 1846 • Fe., height on tide scale " ' 2700 Lowest Low Water, occurred December 20, 1^6; height on f i.le scale! 1 -40 Iho extreme difference of level observeil was therefore 25 W feet. In the observations of 1898 the tide levels are reduce.! to a Low-water < atum determined to accord with the reference station at .St. John X B The details nmy be given as a further example, as it i. the inetho.l gem-rallv use""'= """ ^^'"■" •'■'• ♦''•'" "--•";"- .n l,e?H , 1 'ft • ;'■" ''""" "" '""'"^ "f aseertaininK th,- datun. phw.e used m the onKn.fli .\dnnrahy survey of the harl.our or in the later survov of the entrance to the harbour, n.ade in I8K7 l.y the Public Works departn.ent". There was no cty datum u, use :.t the tin.e, as the s.eep slope of the 'tree.s was t' k,!^^ a. vanta,. .. ,„ ,,, , the eity works by ditferonee of level without r:fe^ n" to aji> OIK- datum plane. It was therefore n..,es,sary to nwletermine a I.ow-water -latum whi.-h rc^pured eare m .leahuK with a ran^e of 2.5 feet, by which all ,he variation of exel are mu.h n.creased. The sp,.,.i»I feature of the ti.le, in the Hav of Fundy ..a vanation „. ran^e with the n.oon's distance which is Kreat.-r than tlu- ^ari- at...,. fron. SprmK to Neaps. Ffonce when ,>eriKee falls at new or full m.K.n ti'tC'^rr '" ' ' '' '"" ''''" "^ ''''"'"''''' '^"""'^ ^'''"^ '->• -"-'t . 'Pl "'»"•' "f '•'« i;"''li<' Works .lepartment for the breakwater at N.^ro Po n show the level of HiRh Water an.l Low Water relatively to the surflo of the planking as ., feet, and M) feet ti inches, respectively. This presumably defines the Pubhc A\;orks Low-wator datun.. The levefs at the l.reakwlt r rea .Ks at H.^h A a er; and the resulting .latum as thus a.scertan.e.l is given ^.th the present tnle levels. The Publi.- Work.s datum a.iopte.1 bv Mr i: T P ManTh '"l 'r' "r! "'7' "'."'" '"' "'"^ "'^■"^'''^'"^ '•'"«'"-'- «■- « "-heslower than th<- .-l.vation thus f.)und fr.Hu the breakwate pla..e,| sum.-iently low that few ti.les in the .ourse of the rZo'"?' , r "■ ■'" '■'"'' "^ "'" ''"■«" -<''»i-""'"hly i.uH,ualitv in the range, ,t ,s there ore .pate nc-essary to has., the Low-wafr datun. on the average level of the l.,wer of ,he tw.. .Spring ti.les .,f ,ho monU.. .After lon.e tna con.par.s.,ns an.l .-..rr.Hti.^ns. the datum a.lopted in Xovcn.ber IH!..! wa^ builiin" T. ,";"■ ''■"" '"" '"'"" ''" "-'■''-"->< - •'"• Huston. House -ear S- . 1 ,"'" " ""'"•^•"''''>' '''"'^••' •''"•^•"" I-« Water, as .luring the ear 18'Ja by wlu.-h „ was t.-sf-.l when i, was a.lopte.l, there were six t.d.^ ».a .,uhce.i .,r fel below i,. I,s r..|ati..n to the .\verage level of Low Water as .le ern,m...l by (he stan.lar.l meth.,.l in which both the Spring tides ,.f the ""•nth are mdu.l.^l, is shown in the ti.h- levels her., given. ihis Low-wat.-r .latum has lK>en .naintairu'.l instantly since imr, .„ th. reduct..m of the obs. rvalions an.l as th.- zen. level .,f the Tide Tables. 1, wa- ad..p e Low-water datum established by the Tidal Survey in 1895, being the zero level from which the height in th<- Tide Tables i.-^ measured. Also adopted by the Public Works department 44-40 Lowest Low Water observed from 1901 to 1908; (Kcurnnl in 190r>, on February 21 43 • 4,'> 83 Inlet to tho tido kiiuko, nt 10 iuclics al.ovi' the hotfoin of tin- ti.lo Kuumi '•ylincier ^,.,.^ Bottom of the foundation cylimlcr, filleiiin<-«<. Iii|("» -0 40 :< :«) -0 111 :i :ui 'jriiiK tiili-ii. MiMtll't ilixlanif. Jnii. I- VI), Fill .M»r Miir. Apr. :ii III •-'H IS a I III Vn-i. n m a 40 010 jl'ifiwc lAixigii'. lUv ny FixDv. (TpiKT part.) TownnU the head ».f tlic Hay of ImiiiiI.v, from Ic.califios whoro tho raimn »v\((»ri|« ;r, foot, thoro aro no wharvus whiili i-xtcud Ik'vi.iuI half tide. Tin- nuiiK. -M small Mtcamrrs in th« iippi-r part of tlu' \my liavi- th«rcforc> to mak«« tlwir ;all.s at IliKh Watrr and ioav.- promptly. S,li(M)n«'rs arc acfomiiKMlati'd by lyiiiit on a iH-ncli of mat tress- wi.wk, ajjainst the wliarvcis, while tho tide is down. For the piir|)ose» of naviKa«ion, therefore, the inoMt essential inform- ation is the time of HiRli Water, as it is oidy then that wharves can l)c reache8, in the upper r>art of the bay above Nt..b)hn, were .ibtaincd at Ho|M>well cape, opposite Felly i':.int in Chiitnecto ehaimel, from July :JOlill November 1.'); and at Mom ton irom Aiinust 10 till Novenil)er IS. Also, in the eastern arm of the bay, at I'arrsboro piisr from July 22 till ()ctol«>r 14, ami at Wind.sor, \ S. from AuKU.st Hi till Novemlier 18. -Moncton and Windsor are so far up the rivers on which they are situated that the lower levels of the tide are cut off by the river slope, and the tide does not fall to true bow Water. At the other two localities the Low- water liiK^ i.« far beyond the end of the wharves, am! is of little concern to iiaviKation. With regard to the complete raiiue ol the tide, and its variations at both IliKh and Low Water, the data have been obtained at the extreme head of both arms, and will lie ^ivon conci.sely further on. For practical purposes therefore, next to the tune of High Water, which is thir chief es.sential for any naviuation, the important matter is the variation in the level of HiKh Water at diffenjiit times in the monlli: as this aflfc-ts the 8A <»"• ......1 of tho Imy nn. aUo .,f ..,.s..,.t.Ml in,,,.., (an.,. ,„ ,|,.. aur,.„lM.r,.l .nt..r..M. ... »h" pr.,f,.......n of ,lvk...l l,.n.|.. Tl..-,. ..vl,,.,,,... h.-.v,- I,...,. oI.mmv,-.! for ■ ....n.lK.r o y..ar. I.y .hi. Survy, „t S„..kv.ll.. harl.our, Korf r.,.wr..n....,lo..k .n,'l .\...I..T.. h,ul,<..,r .n („n.l„.,lan,| 1.,.^,,. wIhto .h.-y ar,. .|,.fini,olv ,,.f„r,„., ,., I»«-n.-h-n.arkH; an.l th.^ Ti>m\u will l„. s,n„ni,. -iz,.,! |„.„-in. o,..lv'.'.n"li!"T '" "'. ''■'"' ."-^ '"'!': "■""'• ''■'"•^" ^■"' '""••""• '" "•'"' I'"'"- o.iHV on . ... fo„r ,n,lo,„.n,l..n( ti.l.- .,al,.. .h„i„;j ,(„. s.-ax-n of IW.S, »„■ ^mv,.|, ...»»... tul.!,. iH-low. Th. avvraK.. l-v.-l of HiKh W„„,- a. .1... S,.,i„K an.l X.ap M.I.-. r,.,p...„vHy wa. .lo.,.rn.in.,l fron. fl„. nu-an of ,«.. ,.ons...„,iv,. I!.,, I. A\a..-rs at ..„.•. of .1... Sp-.n^s an.l \,.„ps ,l,ro„Kl.o,„ ,1... ..a..,,,, ,„ Hi.ninaM. ■ rs, ..olun.n. T ho gn-a..., an.l l.-a., lu-iKl... in ,ho n.-x, .wo ..ol,„..n!; an 's . ly .ho ,n.«.,..t an.l loan. .,.„lo roa.linKs a. 11,^1, Wa.or a. .ho various lo..ali,i . AI.ho„Kh ho «,ro.s of ,hoso M-alo.s hav- no rola.io, a.-h o.hor, .ho »...!„,.« u:oHiih'w'7"r"r''''',' "■"' I'r '"' •"'"•"" «'"'^ ••"■ -•"""•-• ''"t-— '- thrinK!<. Ho|H'W)'!l .•llJM'. M.m.'t.Mi I'arrHhuro pier. Windimr Kwt. 617 « 04 Auk, -i 14 !».'. AiiK, .il* 2S 40 SWJ |.S,'p,. I ii>.(i,-i li.'iKlit .if IIikIi Water : Kx,r.,i«' r ililTcri'iii'c III II W . :il N <^l|MI. ll'Vl'l ( Datr I'.H.l. Km . Sf|>l III ;i .w II .,-, S,.pt 10 17 10 11 30 Sept. II, ID 70 u ur. < h't M i ar, 10 10 Monrto,,, .V./y. Ti.lai ol.Mrva.ions woro ..l.,ai,io,| horo in IKON f. . Au...t .0 .o Xovon.lK.r ... Tho n.«..orin. .a..." ^ s . a 'in ^ wharf a ,l,o foo, of IMoasan, s.ri... Tho .i.lo oohnnn w .s a. al' . ,ho ^on 1.0 whar., an.l ..on.inuo., .,..wn „ r... i.„o ,|.o .roun.l a^a .'jl T ma lo of 2-.n,.h .ron p.po. I ho ,„|,. .....p.io.l an.l fiilo.l ,h,s w.-ll I.y Mphorin.-' ::'J^:!:i!T:;lx:r''- ^"— - -..,., ai. ,.,i!::s For tho .i.io lovols. .1... .\r..n,,„„ ( ity ,,.,„„„ „,„ ,„„,,^ „^,. boon oarofnily os.a..hsho.l a,..l ro...r,v.l ... Ho.H.h-.na.ks I.y Mr.V.. W A . > a whilo ( .ty Kn^inoor. To av..,.| n.ua.ivo vah.os how vor. .„ ..x.,-, 11,^ h.: cev.„.ons .o .noluilo ti.lo lovols, HK, f... is hon- a.l.Io.l ... .ho C . v i. ^ m .h<. sanio way as at Sy.lnoy an.l Halifax. ' "''"'""■^' ri.y Ik.,.c.|.-,.,ark; .ho snrfaoo of ,1... s.ono ,|,.o,-sil| of ,h„ rhy lUnUUu^ .uldoil, 12S 10. hl.'vation in .ho ( Mo.loli.- lovols. ;i.i:)2. J nn City Hoh.h „iark; oti a |,r„k IxitLliim with m„w roun(i I, „ HfiiHi-Uiark i. fh^ top of the xiotix rouii.liition at th« lonier of those Htrw-l!.; whirh is hInmiI nn ...h aU.vo thi- hvcl of tho -id.mulk Vmnl for reference in 1N08 f..r the ti.lc I.v.'Ih. City i»l. vation, with UK) f.^'t a.Mo.l, |;« ftl Kh'vation in the (icMNletii |«'v,>ln, 4« 70. rnl)lir Workii Bwiih-nmrk at ihr troi,i (n surface of the ..tone .I.K)r Mill at ea^t -i eaxtirn .'ntrancc.. City elevation with KK) fi^t ft.hlnd. Iin ,T1. (It,.- .Irvation of thin Ikiuh-inark alM>ve the Piilihr Work, .latum is loi j;. Il.gh Water at onliiiary .SpriiiR liden iM'inE tak.n .iw MX) (M) f.^.i.) Kli'Vtiliiin i:w r.i l-.tMO 110 ori IIH !H) 117 Oft 1!.'. ;T«> 108' oti UK !)K neiirh-fnark an .IcM-rilrt'd, cnrjier of f)ukc and Main streefN Tile Saxliy tide at Montton. wlurh rwpurrod Octolier /), I . H, |s«»tl; fron» levels taken l.y the Intercolonial railway KnKine*-!^. I,y refiueist of thin Survey. (This tide broke over tho ilykes alotiK tlie I'.titiiMliac river. IkiIow Moneton.) FlJKhisnt Hinh Wnlor in the season of 1898, from AuRUst to Novond>er; < '\ AuRUSt .11 Tide levels adopted by the Publii- Worku «leparlm.int for r..n. fltructioii of wharves: Hinh Water Spring tides (P.W. elevation lOt) (K)) High Water Neap tides (I'.W. elevation JKJ-.'W)) Cap of Dunlap's wharf, at south-west eonier. Klevation in August 1898 ' Bottom of the tide well of the gauge 'sStili Lowest Low Water during the scas«jii of 1898, on October 20 8', -80 Extreme Low Water, opposite tlie mou'l, of Hall's creek; as dcUer- miiu'd liy Mi. MiCready while City Kngineer 877'> Tho full range; of tlH> tide is not obtained at -Moncton, as it is so far up the river that Low Water is cut off by the livcr slofM\ I'liriKboro i,ivr. Tin- Hiuich-mark to which tin; tide levels of 1«98 were leferreci is a chisel line with a broad arrow iudow it, cut on the south wall of a small stone building, formerly use(i as a school, at that date u.sed as an ice-houso; situated asfollow.s: At 290 ftwt from shore end of pior, along the main road leai'ing northward to the town of I'arrsboro, a cross road tunis westward; the building l)eing on the north side of this cross road, at 200 feet along it from the .(inier. Geodetic elevation of this Be.ich-mark, 07 -24 fwjt. A beach of .our.se «ravel which slopes back on tho landwaid side, extends m a wide .-^wcep from the ,)ier to Partri.!):, island. As it is overHowetl at extreme tides, Its elevation is given to indicate the level tl / High Water may reach. s? filrvn'uin lOUllU 57 02 M •70 M 30 ■>5 .•i;j .14 NO W 07 4(i W.i •,u ir. IH 2:. n*'n(li.tnHrk, ao iltMrriliml Top «if cap of pior, nt nhc»r<> i-nil [ Top of rap Ht oilier oiul of pior. in IWW * .Vi 55 Kxtri'iiio IliKh Water, wlu.h ovorf1ow»t thn greater part of the pier Hidhi'nt Uivfl reothtMl an point^i out hy ii mininifr n«Ki.l«iit who hail iHcupiwI a cottaRi* chuw («> hnad of |iier, for »«v«ral M^oMtm Top of gravel Iwarh, HN linitrrilifKl High ti.ln which overHowwl the pier in July. ISfiS; ax markmi at tho (ime by the craw of a loial MnaiiK'r Hinhoxt tiile rocort level recorded hy the tide gauge .' •Surface of Ijoach at outer end of the pur; dr>' at I-ow Water Low Water at Spring tide,*, on July 23; ohMerv.'d while gauge wa- lking on'ctep of the grey granite plinth, at tho east corner of the building, Mow the brickwork. Klevation above Railway datum. irtHHi. The buildings alwve described were burnt in the previous autumn of 1807, when the town of Windsor wa.^ destroyed by fire; but as they havi^ Mm rebuilt ..n their old foundations, it is not likely that there will Im» anv .settlement to affect those Bench-marks. l.l<'V;lt4ttn. Bench-mark A, as described KMIOO Beiu'h-inark B, as descrilKJii 10003 (^ap of wharf, at side of tide gauge ».•>• 19 Highest High Water in tho season of 1898, on September 1 o:{.7o Mean High Water at Spring tides; l)eing the average elevation of tin- two high tides of tho day at each of tho Springs during the soason; tho diurnal inequaUty lioing thus ehminated •)2- 10 -Mean High Water at Neap tides; determined in the same way 8»i 24 I MICROCOPV nSOWTION TBT CHART (ANSI ond ISO TEST CHART No 2) _^ /APPLIED IN/MGE In^ ^B^ii '653 Eost Main Street P^S Rochester. New York U609 USA ^S (^'6) 482 - 0300 - Phone B^SS (^'6) 288 - 5989 - Fqk I 88 Lowest level recorded by the tide Range 81 07 Surface of mud beach in front of the wharf; at much the same level as at the other wharves along the water front 8000 Cumberland Basin.— An excellent datum for reference in this region was established dunng the surveys for the Baio Verte canal, in 1870; and the same datum was adopted for the Chignecto Marine Transport railway, which was never completed. These schemes were both intended to connect the navigation m Northumberland strait with the head of the Bay of Fundy for through transportation. The datum is defined by the level reached by the Saxby tide which occurred m the autumn before the surveys of 1870. It occurred at 1 a.m. on October 5 1869, and was an exceptional storm tide which flooded the country, as the extensive dyked marshes in this region cover many square miles. The datum IS defined as 100-00 feet below this extreme level; that is, the height reached by this exceptional tide is taken as elevation 100-00 in the system of levelling This datum is an unusually valuable one, as similtaneous tidal observ. ^ons were obtained during five months in the season of 1870 at Cumberland Lasin and at Baie Verte on the two sides of the isthmus of Chignecto, which are both reduced to this same datum. They thus afford a comparison between a tide with 7 feet range on the one side of the isthmus and nearly 50 feet range on the other. The observations consisted of levels only, the time of the tide being Ignored. They were also Umited to the day time, and only one High Water is obtamed on each day, together with a few levels of Low Water during the course of the month. Such levels require care in their reduction to avoid misleading results; but the method of dealing with the diurnal inequality will be explained. j " These observations were originally published as an Appendix to the report a" -f ^^'^^^f '^ -?u '^ y^'*^ *^*°^'' ^y *^^ ^"^"^ ^'°'-''« department, dated April 12, 1873. They have now been republished in " Tides at the Head of the Bay of Fundy," issued by the Tidal Survey in 1916; where the data re- garding the features of the tide to be deduced from them, are fully worked out At the southern end of the Marine Railway .here is a large excavation for the terminal lock, named in the reports the Fort Lawrence dock, with an engine- house beside it for the pumping station. During the tidal observations of 1898, the Bench-marks m this vicinity, by which the Marine Railway datum is fixed were examined. They are on masonry culverts under the railway roadbed! and with the help of the original working profiles they were located and their elevations ascertained. The stone of these culverts is of a soft nature, however- and by 1901 it had become so much weathered that the Bench-marks were icnl ., ' ^"^^^ ''''^^ *^^ ^"" description which was noted on the t- md in 1898 Also, the difference in elevation o; the two best of them, wh re withm half a mile of each other, was found to have altered, being appa. due to the cracking and settlement of the masonry of the culverts on which they are cut. This difference of elevation on the profiles was 3-44 feet but in September 1898, the actual difference in level proved to be 3-41 feef and in September 1901 it was 3-39 feet as shown by levels run three times f^om one to the other. Values were accordingly adopted for them to average this iftt. 89 discrepancy, then amounting to 05 foot; and the average value thus obtained was used in establishing a new Bench-mark, which was cut on the engine- house at Fort Lawrence dock. This was further connected in 1913 with the recent Bench-marks on the main line of the Geodetic survey, running through this region; and the valuable datum for the tide levels of the Baio Verte canal and the Chignecto Marine Transport railway will now be preserved without peradventure for the future. It was desirable to continue ob.servations of the extreme levels which the tide might reach in different years; and as Fort Lawrence dock is an uninhabited locality, there was better opportunity at Sackvillo harbour, near the mouth of the Tantramar river, in the vicinity of the railway station. Accordinglv in 1901 the Marine Railway datum was carried a.ound the head of Cumberland basin to Sackvillo, a distance of nine miles, by means of instrumental levels run by the Tidal Survey. Several intermediate Bench-marks were established on this hne, as described in the Report of Progress of December 6 1901 The terminal Bench-mark at Sackville was placed on the masonry foundation of a dwelhng-house, and was afterwards transferred to the now masonry railway station, when this was built. When the precise levels of the Dominion Obser- vatory were available in 1914, tho difference between Ih.i Bench-marks at Sackville and Fort Lawrence dock was corrected by 0-05 foot, to accord with them. This correction is made in the tide levels at Sackville relatively to the Marine Railway datum as defined by the Bench-mark at the dock. When wharves were built in the mouth of the Laplanche river, which is known as Amherst harbour although some miles from the town of Amherst a Bench-mark was established there also; and the elevations of some extreme tides have thus been obtained from observations by the Harbour master In the information for this region, we may limit the tide levels to a t^eries of the same character as for the other localities around tho Bay of Fundy Amongst the Bench-marks described, two of the Geodetic series are included The tops of the dykes in the region are also given, as found in the extended levels of 1901, to show their elevations relatively to the extreme level of High Tidal Survey Bench-mark at Fort Lawrence dock; established in 1901 to preserve the original datum of the Marine Railway. On the north end of the engine-house beside the dock; a step-notch cut in the string course of sandstone at the foot of the westerly of the two middle brick pillasters. It is 5 inches long, and level with the edge of the champfer of the sfimg course. Elevation according to precise levels of the Dominion Observatory, 29 095 feet above Mean Sea level, in their series of elevations. Bench-mark at Amherst harbour, at the head of the outer wharf. A small square cut on the south end of the coping of a masonry culvert, abo^t ten feet from the shore end of the wharf. The figures 95-57 are cut on the stone beside the mark, which is its elevation above the Marine Railway datum. Geodetic Bench-mark cm. At the intersection of the Chignecto Marino Railway with the Intercolonial. On a ulvert under the Marine Railway and parallel with the track of the Intercolonial Railway on its west side, at 525 feet south of Fort Lawrence station; a copper bolt in tho north face of the culvert 90 3H foet holow base of rail. Gco.loHc elevation, 2(}.40 fc-t. Dominion C-bser- vatory elevation, 26-60 feet. umiUHin ». oser- Tidal Survey Bench-mark at Saekvillo. On the masonry Raiiwav station iHuhUnK; the surface of the granite sill of the middle door at the back o eas ci^t^'on th ^.T'T; J'?"^**^ ^"^ "^ '"^^ «'" '»-'^-' '»' an inverted broad rr" cut on the side of the door, with the letters " B. M." above it Geodetic Bench-mark, m.cccc.xx.xvi. On the Sackville station building- number ''«' ^f.^-'f-l'^"" 'o^ ^'" ^^^^ ''"' '^^"' ''"" "'^'^''^ -^^ the S number. Geodetic elevation, 27 21 feet. Tidal Survey Bench-mark of 1901, on the Engine-house at Fort ^'""""' Lawrence dock, as described ... 101 4'> Saxby tide of October 5, 1869; defining the datum of the Bale Verte Canal and the Chignecto Marine Railway, as 100 feet below it . 100 ■ 00 Bench-mark at Amherst harbour, as described q= -- Geodetic Bench-mark cm. near the Fort Lawrence station '. ag.q!^ TidaUurvey Bench-mark at Sackville, on the station building, as described Geodetic Bench-mark m.cccc.xxxvi. on the Sackville station building . 99-70 Average level of top of dykes around Cumberland basin. (See details in table given.) o- -jo Exceptional High Water of August 1908 (probably Aug. 12). From the level reached by the water at three points near the wharf at Sackville; mean elevation qr o-j Exceptional High Water of September or Octoberl906; at noon on a calm day. As marked at Amherst harbour q« 70 Highest High Water at Fort Lawrence dock during the observation. ' " of the Baie Verte Canal survey, from August to December, 1870 Occurred on October 25 at Spring tides during a S. W. gale 96 - 00 Mean ntfw I Tf °"' ""'l'^*"^'^''^ ^y storms, on September 27. ! 94-60 Mean High Water at Spring tides; being the average elevation of the two high tides of the day at six Springs in the later part of the season; the diurnal inequahty being thus eliminated . . 91 . 00 Mean level of High Water throughout the month; based on a period of four lunar months during the observations of 1870 89 -2« Mean level of Low Water throughout the month, during the same four lunar months In these two mean levels, the inequalities during' the'montli' are ^ averaged, by taking even lunar months; but the diurnal inequaUty is not fully ba anced out, as the observations were in the day time only. Mean Low Water at Spring tides; being the average elevation of the two ow tides of the day at four Springs in the later part of the season- the diurnal inequalty being thus eliminated . . 50 21 Reference level taken as extreme Low Water, to which the Marine Kailway soundings are reduced. (Defined as 2-75 feet below Ordinary Low Water" at elevation 50-00, a. adopted by the Baie \ erte Canal survey) ^ .„ „. ^' 47-25 91 Lowest Low Waters olwcrvod during the five montlis in 1870; on October 2f) and Nov(nul)er 24 (excipting one durinR a Kali>) .J7.()() Low-watcr datum, detenuined with relation to the St John datum by the Keneral method already explained, based on the fides at ,St. John as specially calculated for 1870 4«-98 In the values above given for :nean High Water and mear Low Water at .Spring tides the diurnal inequality is eliminated by computii',? the elevation of the missing night tides from their corresponding values at .St. .John in the tide tables calculated for 1870. In the values for the meai level thn^ughout the month, the diurnal inequality is not fully eliminated, as explained. In both cases however, the large .semi-monthly inequality is carefullv eliminated by the methods employed. This inequalty is due to the difference between perigee and apogee .Springs, and it may occasion a difference in level of r, to 6 feet m either High Water or Low Water at succes.sivo .Spring tides. With these explanations, we may proceed to make a comparison of the Half-tide level, based on the best data which the observations afford, with the values of Moan Sea level carried from Halifax by the recent systems of precise levelling. Mean Sea level— The values at the head of the Bay of Fundv antl in North- umberland strait, on the two sides of the isthmus of Chignecto, an given below They arc based on the elevations of the Bench-marks already mentioned, and on the tide levels above stated. Mean Sea level, according to the precise levels of the Dominion Observ- atory; based on the determination at Halifax by the Tidal Survey. (From their elevation for the Bench-mark on the Enginc-hou.se at Fort Lawrence dock.) 72-33 Mean Sea level, according to the levels of the Geodetic Survey; ba.sed also on the Halifax determination. (From the elevation of Bench- mark CM. as connected with the Marine Railway datum.) 72 03 Half-tide level in Cumberland basin; between mean High Water and mean Low Water throughout the month, determined as above explained 70-77 Half-tide level in Cumberland Ijasin; between mean High Water and mean Low Water at Spring tides, determined as above explained . . 70-71 Half-tide level at Tidnish, Baie Verte; from 48 days on which both High Water and Low Water were observed, between August and December, 1870 71-18 The divergence in Cumberland basin from the oceanic value of Mean Sea ., may be due to variations which are not completely eliminated; as the Low Waters observed are so incomplete, there being only 13 per month on the average. It is also possible that the tide curve may be modified in the direction of the estuary type, and be unsymmetrical. In the other arm of the Bay of Fundy however, in Cobequid bay, where the form of the tide curve was accurately determined, it proved to be strictly symmetrical. The correspondence is sufficiently near in any case, to show that Mean Sea level at the head of the Bay of Fundy is closely the same as in the Gulf I I 92 «t th.. ho„, of the hay. .k equally ahovo and l,ol.,w fl ,. tr.io .stan.linR l.-vol of he «oa. .f horo wore no tulo. It woul.l app.ar also that in ^tonns, tho level alls a.s ,nu,.h below or.hnary Low Wafer a« it raised above ordinary Ili^h Water It .s oxtnnated tl,a( the Saxby ti.ie fell to elevation 42-50, which from th,'. riy^S'tnL'Sftr''' '"^^" '' "'-" '-•■' ^--^ -"^••" ---- _ Level, ,f the to,, of, he ,l,/ke>..~-Tho ,lyke« an, built to reclaim the extrensivo mar. u^ or hay an, Is between A.nher«t and Saekville on (Cumberland basin, Bay of Pundy. The elevation Rivon in each ease is the averaRO level of severa pom s on the dyke. The relation of the \ '''"""""' of extromo HiKh Water. KInvafion adopUul, . „Mi rw. l-« "»^'« t° include Low Wate aiao, which was not observed elsewhere. The elevations are from the same datums as already i-ed, which are quite The greater differences in Cumberland basin are apparently due to the would naturally occur. In the values for Cumberland basin, two extremes during storms have been omitted. extremes n:» At IIkiii Wattr. At lrf)w Watrk. I oculitifH nt llciul i.f I Hinhi'Hl l^iwi-nt | F.xtrriiie I I^iwi-i Highrxt Kxtrcriii' Hiiy of Fiinily. | ilfvution ; iliviitii -i dilTiTfiiic : t'li'vutioii ilrviilioti ililTi'ri'nri' CiiinbiTlnnil biutin. ColMKiuiil buy lit M|iriii)(H I itt Xiv [w^. : tu Irvi'l. I IHtMl ! !•! IM) H'JU nt HpringM Krrt. 47 00 46 32 lit Ni>ii|M. i ill li'vrl. K