CiHM ICIMH Microfiche Collection de Series microfiches (IMonographs) (monographles) Canadian Institut* for Historical IMicroraproductiont / institut Canadian da microraproductions hittoriquas Technical and Bibliographic Notes / Notes techniques et bibliographiques The Institute has attempted to obtain the t)est original copy available for filming. 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Thl« Ham la filfMd at tlw raduetion ratio Ca doewnant aat flbnA Ml taux da rMuelioR lOx 14x 18x 22x 28x 30x "7 12x lex 2Qx a4x 2tx Mv TlM copy fUmtd h«r« has bMn raprodu««d thanlM to th« g«n«ro«itv of: National Library of Canada L'Mompiairo film* fut roproduit grleo A la g*n4ro8iti do: Bibliothiquo nationalo du Canada Tho Inwfloa appoarinfl horo oro tlio powMklo eonaMoriiHl tho cendliiofi of tho oviflinal eopy ond in hooping filming eontraet apoolf ieotiona. quoUty logibiiity Originol copioo in printod u _ boginning with tho front eovor ond onding on tho loot pogo with o printod or Muotrotod improo* •ion, or tho boeit eovor whon opproprioto. All othor originol copioo oro fUmod boginning on tho firat pogo with o printod or illuatratod improo- •ion. ond onding on tho loot pogo with o printod or Hluotrotod improo^ion. Tho loot rocordod fromo on ooch mieroficho •hoU contain tho aymbol «♦> (moaning "CON- TINUED"), or tho aymbol ▼ (moaning "ENO"J. whiehovor applioa. Mopo, plotoo. charts, otc. moy bo filmed at difforont reduction ratios. Thoso too Ivrgo to bo ontiroly included in ono saposuro sro filmed boginning in the upper loft bond comer, left to right ond top to bottom, as many frames aa required. The following diogroms illustrate the method: Los imogos suivontes ont *t* reproduites svec ie plus grand soin. compto tenu do la condition et do lo nottot* do i'sxemploiro film*, et on conf ormlt« ovee los conditions du contrat do fHmogo. Lee OKomploiree origineua dent la ceuverture en popior eet imprlmOe som fllm^s en cemmencant par lo premier plot et en terminont soit psr Is denMre pogo qui comporte uno empreinto d'improssion ou d'illustration. soit par lo second plot, colon lo COS. Tous lee sutres exemplsiros orlginoua sent fUmds sn eommencsnt par la premiere pogo qui comporte uno empreinto dimprossion ou d'lllustrstion et en terminant par la demi*re pogo qui comporte uno telle empreinto. Un doe symboles suivonts spporoltra sur la domi*re imege do cheque microfiche, sslon Ie cos: Ie symbols -*> signifis "A SUIVRE". Ie symbolo ▼ signifie "FIN". Los cartes, plonchos. tableaux, etc.. pouvent itre filmte k doe tsux do rMuction diff«rents. Lorsque lo document est trop grsnd pour ttre roproduit on un soul clichO. il est film* A psrtir do I'angle supdrlour gouche. do flsueho * droite, et do hout en bos. en prensnt Is nombro d'imeges nOcossaire. Lea diagrsmmes suivants illustront lo mOthode. 1 2 3 1 2 3 4 S 6 AMCROCon MwuinoN mt omit (ANSI ond ISO Tf ST CHAIIT No. 2) A /^PLIED IN/MGF 1653 Eaat Moin StrMi "Jt""'". N~ rof* 14608 USA (716) »82 - 0300 - PhoM "^ (716) 288 - Mas - fa. I ^ I i ^ I I I ill I M EDWARD VII. •EMIONAL PAPER No. 81o A.1fOt SUPPLEMENT NO. 1 TO THE THIRTY-EIGHTH ANNUAL REPORT OF THE DEPARTMENT OF MARINE AND FISHERIES TIDE LEVELS AND DATUM PLANES on THB PACIFIC COAST OF CANADA mr W. BELI. DAWSON. M.A.. D.So. F.B.8.C., M. INHT. C'.K., Engini«r in Chargt of th> Tidal mid Cnrrtnt Survey of Canada. ii PBtSTSD BY ORDER OF PARLIAMEAT OTTAWA PRINTED BY S. E. DAWSON, PRINTER TO THE KINO'S MOST EXCELLENT MAJESTY 1906 [So. 21c— 1906]. r^*- I 14 COWAIIO Vtl. K8W0NAL PAPER ite A. 1M6 TIDE LEVELS /XD DATUM PLANES on m PACIFIC COAST OF CANADA. Bj W. Biu. Dawkw, ILA., D.So.. FAS.O., K Iwi. OJ:., EqgioMr in Oluigt of the Tidal and Ourrent Bonrey of Ouuda. In «t«diiw the Surrey of TidM and Ourranta to Britidi Oolnmbu on tha «f the tida in tha Tariotu harbonn, and to astabUah aererai now banoh maika. la ^ !!:,'Si.*!?*" •l»«dy aatabliahad, or laral. piarioiuly dataminad. hava ban correlated with tha new work, to aroid confnaion and to giTO tha tida larala a Mtia. •I,"!!! ^'i'^'m"? *»»•«*"*• The krak which a oontinnoua raoord of tha tida afforiL «11 k ralnabla for rafamusa in the oonatruotion of wharfs. di«l«in« and ouT hS bour improyementa. and in city works; aa weU aa for mariiia pwSSes. Owing to tha planning and directing of tidal work on tha Bt. Lawi«nisa and tU Atkitio coast, and tha investigations of oorrents. during tha aarUer wars rf £ 8«Tey u ha. not been possible for the writer to ;i.it tbf Pacifi^JSSt JSu tS; 2.- lor i-iciflc ports, and the commencement of tidal obserrationa Th. nm«^n.{f. -j thH .e.«,n, «ublea U» resulu with regard toXr^%er^d^SS2to?o U a complete form, up to the stage now reached. jV ti«ial obeerraUons. the two essentials are the correct time and a plane of ■e lor height ; a. these are the co-ordinates of the tidal curre. iCmaS ^. thx. Burrey. m a bnmch of the Marine department, is to dTtith Se tiS tion'^f Si r„„*S' *' »^°»* V' l^'^ importance to navigation, and T,^ tion of levels u quite secondary. In the strong tidal currents at ■RrttUhn!!tL^!M. «« information as to the time of slack water tSt is mS^w«tad b^S^^iSTr^ « eoi8t. But the value of reliable levels, which can only be obtained *«,« tM.i «w!^ r.tion.. make, it seem right to take the' addSona" SbU neSs^Sl S aiS tl RnV^V"?*^'?'""'^' publishing such result, is emphasised bTwhS hJt^Z^ Bntish Colmnbia. Bench-marks, carefully established. a«. now uSriSTdTtS uon of a primary bench-mark leaves elaborate surveys with uncertainty in their dttZ Jms, whwh it is extremely difficult to re-determiie satisfwSy By iSbwS J«e records might have been preserved; and a large amount o?good wort J^VS sequent trouble and e^en« in repUcing it. would have been .avi! ^ "^ ""^ The condition of the tide level., a. met with at different pkcee, wa. .trongly oon- ttttted. At some place, of courae, there was nothing to refer to- and it wal ««. SriS ^ rt'^r"'"^" *°*i?^°* " independent benA-mark, a^makei »«Pnmng. At the other extreme, there was a redundance of datum plane.reSii 4 MAMtna AND riMMBMItM §■9 IDWAftO VM., A 1i«lMd hjr TirioiM MigiaMTB aad rantyen with Uttk rtgard to •iijrthiiic prtv doM, tad often otanpUMtM bjr le« of neord. In raoli • omm^ to foQow thu pNMdMl of igBoring tbo |iMt tad bofinninc afiwh, would bar* b«M nnprinci •^•eUIly whoo varaaUo Udo lovtb were ofton MrofoUy rafomd to an unn datuB. In eoDtnat with thb, the Mrrieo midond hy Mr. H. J. Oambio, th« R< i Inffinoor of tlw OuMdian Poeifle Raitwajr at VaaoouTon d w ui TW aMstion. il takan tha troaUa to fumuh Information regardinc lor^ « tha PuUio W'^ ' partBMBt, tba Britiah Admiralty, and tho Oitj ei yanoowar, whiab baa k'p vaiioua idanaa of reforenoa iii relation, and baa avoided uncertainty and coni OlulrMel$r of lAe Pttcifie Ittfe.— The naoat iaaportant plane of rafarenon raanlta from tidal obaarrationa, ia audoobtadly Mean Baa Itval. To oaderatnn boat method of ebtdainc iu valoa^ it ia n aoaa i ary to aiplain briaty the oharno the Paeiflo tidea, aa at firtt tight they appear quite irregular. Ia all parte of tba world, the tidea are found to aooord with the TaryinK nenta and diataaeaa of the moon and the aun. In tha North Atlantie, when were llrat atodied, it happena that they are ebieiy influanoad by the moon's p It waa Uiua auppoaed that tha primary oharaotcriatio of all tidea was a marked nation in bdght from ipringa to neaps in the period of the aynodic month. The tide of tho Paciflc, howerer, can be«t be deacribed at a dtvliimtion tiioal or dadination-month, of 97 -9 dayt ; which it ihortar thi Eodle month aad gradually falla badt Uirou^ iti period in tueeaaaiTa monthi aolar influeaoe ia unusually large in the Pacific relatiTely to the lunar, the t mriatioa ia tha aioro aooentuated. Ob the open ooaat of the Pacific, the tide ct to ia still fairly regular, i thowiag tha ^nraal i wquality atrongly; and in tome regiont, eepecially nortl tha apriaga aaJ neapt can be dittinguithed with little difflculty. But in the Strait of Fuca and the region of the Strait of Georgia, which up half the eoaat line of Britith Columbia and where all the more important hti are aituated, the appearance of the tide cnnre ia anomaloua. The high watei nearly at the tanw lerd; and the range dependa on the amount of fall to low which may be almott inappreciable or Tory pronounced. During the greater p the day, there may Uiua be a long atand or only a alight ihiot 'on near the water level; with a dwrp and thort drop to the lower low water wi.ich occurs oi the day. Thia type only ohangea to a fairly tymmetrical ourre when the moon the equator near the time of the equinoMa. The apring and neap tidea are thna reduced to a aaoondaiy feature whi uaually obecurad by the stronger oharaoterittict of the tide. The 'Eatabii^ht which ia to well marked in the Atlantic, it here almost illusory; unless it is si reduced to eqninoaial and equatorial conditions, in accordance with the definitioi in France. In dealing with tide leTcls, it may still l>e convenient to speak of i and neap tidea, if they are underatood to mean the two maiimt 'nd the two m in range or in level which alwayt ooeur in the period of the lunar month. Bi two highett and the two loweet pointt on the tide curve for the month, may much as five daya before or after the full or new moon, at they are to lar(n>iy sioned by the diurnal inequality, dq;>endent on declination. The extreme tides of the year necessarily occur at the nearest point I solstices at which the moon reaches its maximum declination. A tide of thia character ia apt to be termed irregular by the mariner; i tropical or declination-month, which is its governing period, ia less familiar an noticeable than the synodic month of the moon's phaaee. It it erident, howcvei thia tide is perfectly aatronomical; and when reduced by harmonic analy-i- it diction is just aa definite aa for any other type of tide. r/0« UnrtLM AlfD DATVM fLAXKH to VM., A. 1IM I liMIONAL PAPIR N*. I1« ^fT.f*? ^•'<-Wiih • tid* of tkii (jrp*. Umn U a noubl* dUbiMMt bHwMS th«lMlf-«kb brd. ud tha trftc tiIm of Mmb 8m kml. lu only Meorato taIm U tht BMM ordiiMto lo«ad f>y tho iBtatration of tha Ude oarr*. nfwnd to u^ ia* nriable but lino or datum. This laaaa ordiaaU flnt tha poaitio . of tha koriMiUl liM wkioli MaaoU tha aroa of tha tida enrra ; and thU alao cooorda with tha baat MaitioB of Maaa Baa krel for anjr typa of tida. Wa have oocuion Uter on, to point Mt tba in^ortaaoa of adhariag to thia daiinitien ; m the balf-tida laval may diiar a di^ foot from trim Maaa Baa lara^ araa in tha oaaa of a tide whoae astr«in>> ranga ii only It foot. The adrantaffa of a r^ktariac tida fauira ii much frnphaiiaad with tidaa of thia cliarMtar. If loalo raadi «i .m taken by direot obMrration. whioh tha Admiraltj iurrtyon naually prefer, th«>y miut be continuous, day and niirht, and nftprward [lotted aa a enrra; or little um can be made of them exoept for the redootion of tuundinga. With a reciaterinir gauge, thia elaborate and expen^ire method can be diipeutad with. The hourly ordinatea of the tide eurre throughout the year enable tlu true ralua of Mean Sea lerel to be readily found; and aren with a ihorter period, tht continuity of the reoord enables the diurnal inequality to ho foUow«d; and if thia ii linown, the ararage lerel and the extremea of high and low water, and other data, on be correctly determined. The oontinuoua record i* equally important with retpert to the time of the tide, in which there is a aimilar iivequalily of interral; but widi thii we are not now dealing. Tlie queation of Mean Sea lerel ia of nnuaual intereit on the Pacific coast, as tlwN ii raaaoD to believe that ita aleration is changing. Some indioations point to a rite in tha lerel of the coast, at as high a rate as one or two feet per century. It is only from tidal obaerrations properly reduced, that any tnutworthy reault oan ba arrived at; and if the change is as rapid as supposed, it will not require an interral of many years to obtain a fair approximation to its amount. ! i DATUM PLANES AT VICTORIA. At Victoria and Eaquimalt, the planea of referenoe were found to be in great oon- ftuion, no leas than eight datum planea exiating, unrelated to each other u a rale, tnd tiie recordk regarding them often unobtainable through loss of note books, fire, or destruction of bendi-marks. Most of these are defined by some reference to the tide. lodi as high water, mean sea lerel or low water ; but the tide lerela aasumad do not correspond wi^' eh other, and they are thus quite indefinite unless fixed by a bench- mirlc. To correla . (heae for tidal purposes and to re-determine the chart datuui, it waa uecetsary to go fully into the history of the whole matter, and also to run special Imli for three and a half miles, to connect Eaquimalt with v'i'>;oria. We have alao iiid the opportunity this season, to go over the ground personaLy, to examine origiDal plans iind notes at Victoria, to inspect the bench-marks, to see the records in tha PnbUc Works office in New Westminster, and to discuss matters with those who had W do with them ; in the endeavour to bring all the information into correspondence. We will give the results as concisely as possible; but it will make the matter clearer to follow the chron' gical order. For all practical purposes, anything previous to 1880, if not prehist'>ric may be regarded as ancient history. Bench-mirlu. — There are jevera! bench-marks in Victoria for which elevations >re known with referenoe to more than one datum ; but the resulting difference in- ttead of being constant, is found to vary within the limits of an inch or two. When t relation has had to be determined by averaging such differences, this will be ex- plained. But there are four of the datum planes wlu'ih can now be referred to an individual bench-mark, and these four are the most important from a tidal point of r M IDWARO VIU A. viMT. AU tkt yiMM el ivfMMM at l^alMlt Imt* abo bMu oonsMtod witi "— ^-* " ' f ^ *y 'K'y '•**'» ""» *fa ■>»<■• Hi* filttioM ikM oktolw --^ ttwlwOTthgr tkm if 4triT«a ffMi « t wm ^ aad will, tlwnlera. b« giTra the TIm bMwb>nMk nfcmd to ia at the nonk-aaat m; nar of Wkarf aad Tort t la Yi«teria.'MMl ia th«a Mar Om wattr froat TIm MUiat at tkia m.itm, bow |> Mby,tba,H a«ilto. Powdar OoapuT'a albiL 1mm a aaadatoM fooadation Um briokworii: aad tba tap eoana oftliia fowdattoa. whieh ia aaar^ oa tha lavel tka aida-walk. fonaa tba deer aiHa on tba Whurf atiaai froat of th^ baiUluir. felat oaad aa a bowsb^aark ia tba aarfaee of tba aaaibtoaa, bflow tha brirkwn tha Btiaat ooraer. oaoally tanaad tba ^tbs or alaa tba aentbam aad ef the int aiO. wUab ia twe aad a ball f aet Iroai tba eeraar. Tba le?al of tbaaa two poii idaatiaaL Fer brevity, we may tana tbia tba SUadard baaob-mark. Bu4ton*s Bap CamjMair'a dalvai.— Tbia ia diiaib of Importanoe becauie u* tba baaia el a eoatearad plaa of Vietoria made by Mr. 0. Harrraavw in 18S3. aMMag tbia pbn, beaeb-marka were eatahliibad tiiroacboat tba city ; bat tha •etaa reoordinc thaae were handed f>'ror to the city, and haw been loat f.-r yeara. There are a few polata oa mnjonry bnildinca for which elaration* wii faraaee to tbia datum are marked on the plan itaelf, or are in Mr. HarrreaTes' pi Botra> The datem la deined aa 100 feet below an aiaamed elevation for hluh i Tliie ia ia itaall quite indeflnite ; but in making tha plan, Mr. HargreaTea checW bia kvela baok to tha Standard bench-amrk already deaeribed ; it< elevation I 1«7'11 l«et above tba Hndaon'a Bay datum. Tbia value ia marked on the orii plan, now ia the City Hall ; and it ■ervaa to fix the datum in elevation. C» TlOa LBYMUI 4X0 DATUM fLAMKM m VII.. A. tioi ■ itMioNM. Pknn n*. tia cllM 1 The oiitNWM of OM foot w ooiuidei«4 by Um EiifiiMorinc tUt at t»w Oitj Ball to b* tlM aoti Mcwato Uiat can b« arrlvod at; and thU val '• la the aMoe ae iba difaraMa fivm by o«r Btandani bench-mark. FfM$ W9rk$ AKiMK-Thla ia a Ljw-w»\mt datum aaUblitbed by Mr. ¥. 0. Uamble whil* BaeideBt Enffiaeer of Publio ^ orka. and need u the plane of reference for aewdiagi ia the harboor, and alao for die tidal obaenratiooa of 18M to IMTT. Tkia :■ a amt iavertaat datum, aa it haa beeome the baaia of the ohart of the harbovr. aad haa aioidod indirectly the aUrtihf point for the City levela. It waa tbouffht to be meet definitely fined, with reference to a aeriea of benuh-marka around tha harbour i but unfortunately all record of the elevation of theee waa loat by the dMtroction of the PuMic Work* docunwnU ■' • the fire at New Weatminater in 8e^ innber 18N. The moat peraerorinc effoiU ha a been made to ra-eaUbllah thia datum. MpFcially by thoae intereeted in the chert deptha, the rroundinc of raeaela, and •Iredgin* oparationa; but theee efforto hate been without definite leault until a tru obtiiined thia aeaaon. The Public Work* datum waa originally the zero of a atandard tide »cale • Vr. Oambk to coincide with 9 feet 8 inchea on a tide (auce on the Hudaor' Co't wharf; thia beinc aaid to be the loweat level of low water which had been < . The lero on thia standard Male waa taken to repreaent low water mark at aprinff tidtf ; rnd 9 feet on th** acale, to repreaent high water at apr'pg tidea. Whan the continuoua tidal obaef.r ma were begun, the limiting raluee i^terwarda i«oorded *ert> fl( followa : Eitrem^ high water, 10 feet 9 inchee; eatrame low water, at 8.S0 n.ni. July 8, 1894, 18 inchee below the lero of the acale; making the extreme range 18 ffct 3 inchea. The acale thua proved to be well aet in its height ; aa the lerela of ordinary high and low water fall •ymmetrleaVy between .heae extreme limita. The ficta ai here stated, are taken from a report ot Mr. Oamble'a to hie department, dated Augutt. 1804. The tidal obeerrationa «ere oontinued until Hay, 1807, when the Publio Worka office waa removed to New Weatminater. The only connection by which the Public Worka datum can now be determined. ii 'lue to Mr. E. A. Wilmot It was made incidentally, when be waa eatablishinff the City Sewer datum for Victori* in January, 1801. He accepted the level of feet on the Publio Worka atandard tide acale, as high water at ordinary apring tidea; and he took thia aa elevation 100.00 feet for the City Sewer datn-a. Hia k >la make direct eonni ction from the vide acale, which waa on the Old C >m House wharf, to the bench mark at the comer of Wharf and Fort streets; the connecti.n depends altlmately on a aingle reading on the water surfr^e. Tht .ulting elevation of thia bench-mark above Uw zero of the Public Worka titter appreciated when the Chart datum ia next conaidered. Thia connection has also made the Oity datum the moat deairable one to uae, for the comparison of the rekf've elcvationa of all the other planea of reference. Chart datum. — The Admiralty chart of Victoria harbour ig made from two Muroes; the outer harbour, outside tho line joining Work point and Shoal point, ia from a survey made in 1805 by Lieutenant B. M. Chambers, R.N. This is stated on tha chart issued in March, 1806 ; but there is no reference on that chart to the infor< mation on whi.h the inner harbour is based, nor is ther.« mention of any plane of reference for the aoundinga. It ia now clear that the inner harbour ia taken from the surveys of the Publio Works department. Such plans in that department as have survived the fire, ar« if • MARINB A3fD riSHBUBM M EDWARD VII., A. m pwtid uid ingamtuji but a complete idan of the harbour was known to hav" b« ■MdabefoTClSMby Mr. P. Summerfield. who was employed by Mr. Gamble to do s A wtpgr of thu plan was eventually found in a surregror's oiBce in Vietoria It i ^ttwut fatle or date, but was identified by Mr. 0. Woitfold, assistant engineer i„ th FnUio Works department, as undoubtedly « copy of Mr. -Summerfield's i^n- an mooidingly it u to the PnbUc Works datum that the oompleta soundings given upo ;*«ir »^«»«1- ., It ia also to be noted that thU plan eiisted when the chart, issued i 18W, was oompUed. A oompanson with the Admiralty chart, made by Mr. Worsfol uad myself, with eare to avoid places where dredging has sinoe been done, shows tha tbe soudings are identici.1. The plane of reference for the soundings in thu inn« harbour, as given on the Admiralty chart, is thus proved to be the Public Work datum; for which the elevation is now known through Mr. Wilmot's levels, as alread eq>lained. Tidal Survey datum.— This is the Low-water datum established for the recen tidal observations at Victoria. When those observations wore begun in 1900, by Mi F. N. Denison of the Meteorological service, the Public Works tide scale no longe ezute^ and aD their records were already lost in the fire of 1898. On consultatioi With Mr. Gamble and Mr. Wor8fold,a plane of reference was adopted, to correspon( •s UMrly as might be with the former Public Works datum. The new datum plani was fixed by reference to a new beftch-mark, and also connected with the Siandan bench-mark ou Wharf street ; the elevations being given below. A complete year ol the new tidal observations is induded in the basis of the tide tables, tbe record beini obtaifaed in 1903 to 1904, byllr. E. Baynes Beed, Superintendent of the Met«irolog ioal office, and Mr. Denison. Much trouble has been taken to ascertain the relation of this datum to the chan Mjundings. With this object, special soundings were taken in the harbour by Captair Walbran of the Marine department, for comparison with the tidal record. Timul taneous observations of the water level at Victoria and at Esquimau were also made, in tbe hope of obtaining a connection there. But the reoulte need not be detailed, ai these methods are necessarily uncertain, and the relation has now been ascertained from instrumental levels. This datum is in use for the '"^dging operations now in progress; and for tlie check soundings taken by Captain Jf . Newcomb, who is in charge. The depths as dredged are thus brought into correspondeLce with the sero level of the tide tables. This datum is also cited by Mr. Thos. C. Sorby, on the plan of Victoria harbour which he has compiled and publidied in 1904. The following bench-marks serve to fix this datum : — Tidal Survey bench-mark.— At the rear of the Old Custom House builJing on Wharf street at the foot of Broughton street. The top of a brass bolt drilled ver- tically into the granite rock, at 16 feet from the north-west comer of the building, with the letters ' B. M.' cut beside it on the eloping surface of the rock. Elevation above the Tidal Survey datum, or zero of the present tide scale, 16.'"•<» «n 18»5 to 1897. At a distance below Mean sea level given by the sum of harmonic constants M,+3,+K,+0.. '^''ln'?.'«h iL'it"y-f'**".- *'«"«» 1«T*1 of the two lowest low waters In each month, during two complete years, fpom 1895 to 1897 *"«5f ."«l,'" *''• "*"*•' '*"' ^»'*'" '" «*<=•» "ontl" during the two years. lB»o 10 1897. •.*,,.. '^"m'^*"''* *■'"'"• "" •*""° *»' *"*•'■ "*« •«»'« " victoria in 1893 to! i Dstum of the Public Works tidal observations at Esquimau: 19 feet 6 Inches above masonry sill of Dry Dock .' .. 1 TIdil Survey datum ; the tero for the heights In the Tide Tables ! ^'yZ".^!!.."''^*^"'' *'""'°« ""*• y'^*'^ observations, from 1895 to 1897 and 1903 to 1904. Occurred 1896, June 24.. . I 3111 of masonry Dry Dock at Esquimau Above Victoria City datum. Feet. 116.71 106.10 108.80 100.1* 100.00 96.76 96.64 91. 8» 91.16 90.71 91.00 90.95 90.40 S9.45 71.46 H Jfean Sea level determinations.— Some explanation of these is required, espe- ciaUy as ttiere is an apparent want of coi-respondenee between the Royal Engineers' (latum and Mean Sea level. The various determinations are now correlated by the instrumental levelling referred to; and this also enables the resrlts of the harmonio analyses of the records from registering tide gauges, to be compared on the same oasis. In this analysis, Mean Sea level is the average value found from the summa- lon of the 8760 hourly tidal ordinates throughout the year; and on this principle, the most accurate result possible is obtained. The determinations, reduced to the t^ity datum in Victoria, are as follows : — At Victoria. Tidal observations by Public Works department; two complete years from April 1895 to April 1897. Mean Sea level above Public Works datum, from hourly ordi- nates in each year; 6.728 and 5.776 feet Average eleva- tion resulting 96.75 At Victoria. Tidal Survey observations ; one complete year from March 1903 to March 1904. Mean Sea level above Tidal Survey datum, from hourly ordinates, 6.143 feet. Elevation resulting. 96.54 I«: U MARIKM AND rjBaSUKi B-« fcDWARO VII., A. U At Yietoru. Bogrtl Engineen' datum, at 8.78 feet below 100.00 on the City datum 96.23 At Eaqnimalt Bojral Engineen' datum, in auireyi of 1885 to 1869; 87.84 feet below bench-mark on Esquimalt po»d 95.72 At first aight, it mii^t be considered a better method of procedure to aaw Hmu Sea lerel to haTe the same absolute eleration in every case, and to take i coincident Talue as a basis of comparison for the various datum planes. But ti assumption when carried out, is found to imply a two-fold error in the levels of t different engineers; namely, a minus error of 0.60 foot in Mr. Hargreaves' and the same time a plus error of 0.68 foot in Mr. Wilmot's. These errors do not atti to any assumed values for high water, or such like, but to actual instrumental woi and thegr are therefore quite inadmiss&ble. Some small part of die difference may be doe to actual or physical variation the annual value of Mean Sea level. This variation appears to be greater in t Pacifio than in the Atlantic. The values already given show a difference at Victo of 0.21 of a foot between the years 1896 and 1908. Determinations have ■also be Vnade during a series of years by the United States Coast Survey in California a Puget sound, as well as during five years in the Strait of Q«orgia by this Surv< The greatest variation in level between any two year in the period of the obsen tions is 0.80 to 0.34 of a foot in these localities. The variation may thus be considi able when special years are selected; but even then, it is much less than the lai difference we have here to aooount for. It thus becomes evident that the true explanation of so large a difference is be found in the type of the tide, or the form of the tide curve at Victoria and Esqi malt, to wh:.'h wo have already alluded. Towards hi^ water the tide curve is ve flat, and the long stand of the half -tides is at a high level; while the low water fa sharply and is of short duration. With such a tide, if l^an Sea level is taken the half height or mid-range, it is plain that this may be very different from t mean level derived from its height at every hour throughout the year. The latl method undoubtedly gives the true mean level of the sea; as this integration of t tide curve fumishM the height of the horizontal line which bisects its area. 11 shows also the superior character of the tidal record obtained from a self-regi^teri: tide gauge. The amount by which the values for mean sea level differ, when obtaine•■■■>• Highest High Water recorded by the tidal gauge during six months In ;"'l® '; December 1901. and during the year from March 1902 to March 1SC3. Occurred 1901, December 2< Chart datum, to which the soundings In Vancouver harbour are reduced At 2.3 feet 7 inches below the C. P. R. bench-mark UwMt U>w Water recorded by the tidal gauge during the eighteen months alrpady Indicated. Occurred 1901, December 27. '.. Zero of the tide scale, in the observations of 1901 to 1908. Above 0. P. B. datum. Feet. 108.35 106.00 100.70 100.00 99.76 - 84.77 83.76 St.SO 11 ■ MAMtSa AMD FtBBtatBa »-• COWARD VII., A. II BENCH MABKS AJifD LETEIJB AT OTHEB TIDAL STATIONS. Tidal •tationa aqoipiwd with n^patering gangaa have bean aataUiahad lanent aa a baaia for tha whola ooaat of Britiafe Oolninbia. At thoae of tha graatait stratei laqportanoa, banoh-marin hava baan pot la, and the instnunantal levallinc done p •onally by tha writer. The tidal raooid aeewed will soon enabk t^e more importi i^ landa to be dedooad from Aa obaarratioiia. The tide tealea tued, are of enamel] iron; which are very dnrabla and readily cleaned. Port 8imp$on, B.O. — ^The bench-mark to which tha tide leTelt are refem ia a braat bolt with a round head, drilled into the rodt, in the rooky forediore whi eztenda northward from the HotcA Northern. This ;oolgr part of the foreshore is d at half tide. The bolt ia to the west of the wharf, at 174 feet from the an^ betwe the side of the wharf ud the hotel platform. The elevation of 100.CO feet was asaomed for the referenoe point firat us* which was cat on the rock iu another position. In the summer of IIKMI the fin bench-maric was put in, and the levels completed. The tide levels are from the regiatering gauge which has been in operation aio November 1902. Tide larelt at Port Siai9>0B. r«et. f^Aife Af «rliA.i*f iMBlda tha iida ffAUKA ■• •■ •> ]Q9 ^Q ■stremt High Wat«r, durins ••ran montlUp from Dooomber 190S to June iflAR ifinlnBlv« OflfiuPMid 1S02 DccAmber 18 104 90 Hltfi Water at Spring tUlM Averaca Uvel of the hlghMt High WaMr at 103.26 98 91 Moan Sea loTOl. Deduced from the hourly ordinate! of the tide durlnc one complete year, from February 1904 to February 1906 ; abOTO sero of tide ■AAia IS KAl feet SleTatioD reeultlnc 93 47 Low Water at Spring tides. Averuge lerel of the loweet Low Water at 83.28 Bztreme Low Wat«r during tb« above period. Occurred 1902, December 16. Kant nf tlie tide leale. trom the beatnttins 81. ;o gi).89 The period of tidal observations above indicated, includes the seasons at whic the tides usually have their extreme range in the course of the year. The extren levels as given, are in all probability the limiting values for the year. Wadhams, Biven Mei, B.C. — The bench'onarii is a broad arrow cut on the nx at the south side of the bay in which Wadhams' cannery is situated. It is 55 fe< from the point at which the rock begins, which rises to the southward into cliff Ita level is reached by unusually high tides. TlDa LMVBU AXD DATUM PLAJtaa I 8EMI0NAL PAPER No. 81e A f«»Ut«riii» gaofs wm placed here, and c^Menrationa betnn in July 1W5. If TM« l«T«Is at Wadhamt. ro«t Swbiee of Wkarf, baalda tha Ud« gauce btrtoM Blah WaUr. Klaratlon whieh th« hlgliMt tidei ar« Mid to rtaoh Btseh Mark OB tba roek, at dMorlbcd *"tJS!.f.''..'!?'!f ■.."..'•. ."•"*•'*'• **** "" ""• "•'•' ""• '^'<"' •>•»• Un ot tba tidt loalo lOS.n 101. M 100.00 U.M Sl.W «,.S''^Th^tJ^.Z'T'- "'**^-TW« bay i. .ituated in Queen Charlotte !T 4k ^v •?■*. *? a copper bolt. IJ inohea diameter, drilled into the S o? S! ^W *^\^1 ^ ^^"^•"t ^»»rf; It i« M 'aet from the firat pile bent of the wharf at the shore end, and 8 feet from the side of the wharf. li is It"- r,2»Sf*^*"' f ir*"" *'*^, r**^-. ^« «^"»*'«° ««»"»«» ^o' *»>« top of "his bolt u 100.00 feet, and the aero of the tide scale is at deration 78 37 A registering tide gauge was placed here, and observations begun in July 1906. Bon/IsH, Barclay «o«nd.-This is the Pacific Cable station, at four miles from Cipe Beak, on the west coast of Vancouyer island. Tidal observation, were secured here, from February 1903 to June 1904. with the exception of one month The tide scale uaed. was attadied to the wharf which is immediate^ below the cable oflSoes; and m August. 1906 the elevation of the zero of the soSe wm £S with reference to a bench-mark, consisting of a brass bolt driUed into the ronk at 20 feet from the south-cast comer of the wharf; about the level ' high water. ' Tide levels at Banfleld. Feet. Bench Mark. Top ol brass boU, as described I Low-water datum to which the tidal obatrvations are reduced : at one wot on the tide scale Zero of the tide scale, during the perloo of the observations ; allowing one Inch for settlement ot wharf since then "TO of the tide scale, as found In August, 1905 ' KM.OO 89.40 88.40 88.33 J[o»oquot, Vancouver uland.-The registering tide guage. placed here in August. 1905, 18 at a small wharf, extended to deep water for the purpose, situated near the tel^aph office at the so-called Town site on Uw peninsula opposite Stubbs island m the mouth of the sound. »«aa. The bendi-mark is a brass bolt drilled into diorite rock, at 83i feet from the ; store end of the wharf, on its east side. It is about the level of high water The elevation assumed for the top of this bolt is 100.00 feet, and the'aero of the .de scale is at elevation 86.01. The surface of the planking of the whaJf T.^rS! "Mtely at elevation 107.00. -kh'^* MAMIXM AMD ritMWKIMt M lOWARDVII., DATUM ON THE FKA8ER BIVER i The Department of Pnblio Works Iwt* had thne nfUterinc fkugM on tl portion of the Fruer rirer ainoe 1W5. These are dtuated at New Weetmin! Oarrjr point at the month of the river, and at Sand Heada on the edge of the ■ire thoal which has formed off the month of the riTer, in the Strait of Georg The aero lerel for the tidal obserrationa at Sand Heada was eeUd>liahed F. C. Gamble aa the average of the kmer low watera. The reoord sinoe o1 shows that extreme low water falls some ten inohes, or a foot, below it. The same low water datum ia oaed for the odier tide stations at Qarr.\ and New Westminster. Its level has recently been oarried to the new Poat building by the present Beeident Engineer of Pnblio Woilts, Mr. G. A. Keefei has out a benoh-maik on this building to record it permanently. It is on th* cap on the left side of the steps at the entrance of the Poet OfBoe on Columbia The elevations with reference to this datum are aa follows : — ;'! Ttd« Itvalt on tha Fraaar RlT«r. B«aob Mark on tha Poat Offlce bulldlnK, Naw Wastminatar Moan 8as laral.— Dadnead from tha bourljr ordtnataa o{ tha tida during /Iva raara of obaarration •• followa :— During ona yaar. Hay 1, ISM to May 31. ItN t.4SS " Oetobar 1, ISM to Oetobar ». U>7 t.m NoTambar 1, 189S to NoTamber 15. 1«»S.. ., .. 8.474 NoTombar U. UM to Novambar 14, IMO.. .. I. Ml Januarr It, 1901 to January », IMS S.4S5 Mean valua (or tha Bra yaara S.4t7 Low- water datum. Tha areraga of the lower low watera, used aa tha aeroi laval of tha tlda gaugaa ! Fee 62.; o.c ADMIRALTY BENCH-MARKS. The Admiralty surveying steamer H. M. S. Egeria, has been engaged iu gra{)hic surveys for acme years in British Columbia waters; and its variou mandera have established bench-marks or other reference points to fix the lev datum to which the chart soundings are reduced. Some of theae arc points of natural rock at about half tide level, wbic answer to define a low-water datum for soundings that are only taken to the i foot; but a rock wiUiin the range of the tide, overgrown with seaweed auJ bai in these prolific waters, ia scarcely suitable as a bench-mark for definite tide 1 We give first a full description of theee reference marks in the more inii localitito, or where a continuous tidal record of su£Scient length has been seci furnish a basis for satiafactory tide levels. The record must evidently be couti day and night, to be of use, when diurnal inequality is the leading fcRtisw tide. Snme of the descriptions which are given, are from personal inspectloi Comox. — Chart name. Port Augusta. The chart aurvey was made by Conui M. H, Smyth, R.N., in 1898, and the bench-marit at Oomox serves to define the for the whole extent of Beynes sound. It is of the more importance aa tidal o! tions were secured at Union wharf in this sound, for fifteen months in all, course of the years 1898 to 1900. By means of comiparative observation? m AD VII., A. INI TiDa lawau amd datum hummm ^f KWIONAL l»APER No. 81e th. SjrfhTKirK^lS*''" wharf were uken with • «,i.t.rin, .id. n^, ^ rnJS'.TwiSiS ot" ^ '"" -"• '" *^ »»-'-« ''^^ «' U-Jo- wh«. S. 8,S? ThU Jf* • '^'^ *^ I'^^l of the riab .t Ooow Spit lUgMtio oSSSE ^\t«Zli^ ^u ^; ^f,*".° ''^^ " it in A, -oond «mU bay weat of the Admiralty building nnd wharf if i. bStZ thThi^ . .J^'^^u "»*•*•' Obwrration apot, for ktitude and longitude, whidi i. f.rth«F to the wuth-weat and farther back from the .bore. It i. a^mSr dTof oeSnt- i*fo'r*th'ro^" """ ^^'^ *""'"• '"^ '""'^^''^ marked";"and Jl^^otrSi: • i\ranaim«.— The chart aurroy was made by Commander Smyth, R.N in 18M Th, note regarding datum on the chart of Nanaimo harbour, NoS^'i. „ foS^ _ The datum to which the soundings are reduced is 18.6 feet below the aramit d? Ae nj^ionry beacon on Beacon rock which con«,pond. to ten feet beW ?T«k (S) «it m the perpendicdar rock surface close to the small landing atage on t£ norS The beacon referred to, is a truncated cone of concrete and iron, and ita surface r J^ "^ /"^ewhat rounded. The mark on the rock should ivo Tmo™ Site Jevation; but after careful search it could not be found, owing To the y^^^ Ae description. The mark is within the range of the tide, and the rocks^^^ 25 to^Ma'J SriSr ''*" **^° *""*' '^"^ '"^ "'*^* ^*'' "^^^'^ ^'^ '"" M""** re/«i,rapfc harhour.-JhiB harbour is on Kuper island, on the same body of water mil T ^r?" "^f ,^^'"°'i»' »nd Chemainua; the thrw places being wSin wvm Tf twnlf "" "^*'*,1^ each other from the wat.r. This harbour ^rves as a^rt rtf referen^ for a number of other places amongst the Gulf islands in the Straifof Oeorga. Continuous tidal observations were secured here by Captain J. F Par^ Bunrey. The observations were to be continued in the season of 1906 n«tuS'r^r'"''S.'^i^ ** V' ^"^"^'' '^f*"^ to a bench-mark and ahw to a Mtural rock. The bench-mark is a broad arrow cut in the north-east face of the It 13 00 feet from the summit of the islet, which is two feet above high water T^ Mnm IS 12 feet 10 inches bekw the broad arrow. It is also 7 f Jt 2 ifobi ^!u-^ ^.est part of the weatemmort of the drying ro<^ SiSiuJtui^^ W^ Ime, off the Indian Industrial school. See Chart No. Y14 The additional reference pointe for datum at Ladysmith and Chemainus, which Kie^ " Telegraph harbour, are given below with the other 21c— 2 MAMna iMO FIMMMKMM V i M eowaho VII., A. tm bow'WATn PATvii or mu onium, at onm uioAurnM. Tha foUowing !■ • lUt of the btBdi-msrlu tnd othOT faf«r«ioe p inti which (Mb* Um Low-w«ter datum to which the toundincK h«Te ham wdooed in th. Ad niralty rarreya from 18M, tiU tbair oonolwion in 1906. Tha lUt haa been coi»|)il((l hr Captain J. F. Parry. R.N., of II. M Hurreyinir .tPamer Bg*ria. The localitiea are all lituated on the watera between VaneouTcr ialand ati.l the MainUind. and extend from Queen Charlotte Bound to the Htrait of Georgia. Th.y are giren in their geographical order from north-weat to aouth-aaat ; an 11 fMt 6 inehaa balow tha top of the '>ut<>r mok in tho Mmthprn oorner of the tivn. 8m Chan Na 8887. Port ITarvty.— Johnstone itrait. I^w-water datum at 11 feet 11 indiea below a broad arrow cut on the roeki on tho luain thoro abreast of Tide Pole is|«t Se« Chart No. 684. BiialrtiMop ftoy.— Jahnatoiip strait. I/>w-WHter datum at 7 fw^t B inches below tlw top of a largo boulder Ijrinif three-quarters of a cable north-«aat of Point Oeorg*. See Chart No. 8871. Tidal obaerrations taken day and niRht for 19 days in Hoptember, 1000. V*n eovt.—ln Thurlow iMland, 3 ' -istone strait. Low-water datum at 11 feet 9 inches below tho top of Dorothy rocL. riee Chart No. 581. Chatham point. — Tho dividiiiK point between Johmitunt! Mtrait and IMacovery yuuage. Low-Tater datum at 18 fpi-t below a brc»ad arrow cut in tht? face of the rock on the north side of the small islet lying I mile we«t of Turn island, and close off the uath shore of Thurlow island. See Chart No. .1200. Tidal obserrations taken day and niRht, from July 21 to August 30 in 1000. MtnMiM hay. — Immediately south of Seymour Narrowa, in Discovery passage. Low-water datum at 4 feet 6 inches below the base of the beacon on Defender ahoal in the bay. See Chart No. 538. Tidal obserrations were taken day ami night, in Nymphc cove at the mouth of thii bp from June 19 to August 1 1, 1900. Gowlland harbour. — In Discovery passage. Low-water datum at 9 feet 8 inches Mow a broad a row cut in the rocic at tho south-east extreme of Gowlliind island. S«e Chart No. 3178. (^aathiaiki eovt. — Discovery pnssage. Low-water datum at lo feet below a broad arrow cut on the side of a boulder .it the inner end of the wharf. See Chart Xo. 3162. '''idal observations taken day and night from May 8 to June 4 in 1890. By comparison of the day tides during 16 days in May, with the simuitaneoua obKrvations taken at Union, the elevation of the gcnerul diUura for Baynes sound vu found to be at 6 feet 8 inches on the Quathiaski tide scale. This relation being determined, the datum as above defined is presumably the •une as in Baynes sound, which is referred to the Comox bench-mark already de- icribeil. ilitlenatch M^antf.— Eight miles E. S. E. from Cape Mudge. Tidal observations tiken (lay and ni^t from May 29 to June C in 1899, simultaneously with the observa- tions t Union in Baynes sound; for c-ompari«on of time and datura. See Chart No. S30. .i/nei sound. — See description already given under Comox, of the bench-mark *hich defines the datum throughout this sound; and the tidal observations taken at Union. A(/noos«. — Vancouver island. Low-water datum at 11 feet below the top of a (■■ull rock lying 175 yards to the westward of the northern and highest of Entranced tocits. See Chart No. 585. Tiial obscryationg taken day and night from October 22 to November 16, in U03; and in the day time only, for five weeks in July and August, 1004, for oom- PMisoii with Telegraph harbour. Hammond hay. — Vancouver island. Low-water datum at 4 feet 6 indies beldw ^ top of Clarke rock. See Chart No. 570. i ; I i muww i99 n»MmuBt M lOWARD Vlln A. II Tidd ohMfT^tioM takn la tht day tfaM only, for BMrljr thfM in Ji IIM. D»p»tw Utt.—Thrm milM north of NmwUm. Um-wtttn dntan •« 1h f 4 iaohM bdow Um ■nmmit of Bladi rodi, in Um nortliMii part of tbo tay. 8m Ch HcUii. Tldid obMTTttioM tdwB in Um dajr tioM (miy. for nbont tis woria in ^uly i ▲ngiHt, 1904. D»4d WorrmM.^BotwtMi Mad«« Mimd and Vanooavtr ialand. Low wi datum at SO faot « inehaa Mow a broad arrow cut on tha wattom faoo of a lann r lying 75 faat aaatward of the innor and of tha OorammaB^ wharf at Parojr anchor OD Oahrida idand, wbieh ia within a mils of tha narrowa. Baa Chart No. 3021). Tidal obaarrationa UkAi at Vmny anohoraga in tha day tima only, for nearly waaka in Oetobar and NoTHiibar. 1904. Tha tima of tha tide at Dodd Narrows, foi to ba idantioal with I^roy aiiohora«a, from 97 aimnltanaona obawratioaa eared OaMola paa*.— Batweea Oabriob and Yaldea idanda. Tidal ohaarrationa ti in tha day tima only, for thraa warita in Anfaat. 1904. Tha range U tha tame ii Tdagraph harbour. Thia paaa ia little iwed for narication. Lad$imUh.-€hut name, Oyater harbour. Low-water datum at 4 feet 2 in below the top of the higheet of tha Oluatar rodn, off tha DaMBuir iaUnds. Chart No. 714. . ^ ^ , .„„. Tidal obaerrationa taken for aix weaka, from Angnat to Ootobar in 1904. tima and range of the tide found to be abaolntely identioal with Telegraph harl in Kupar ialand, which ia on the eame body of water. Chtmainui.— On VancouTer island oppoaite Kuper island. Ixiw-wa1»- datui 18 feet 7 indiea below a broad arrow out in the northern face of the email lalet in bay, lying oloae off ahore, about 600 yarda south from the lighthovM. See Chart PorlMf poM.— Between Valdea and Oaliano ialands. Low-watar datum at 11 9 inohea below the top of Black rock. See Chart No. 8099. Tidal obaenrations taken for a abort period in 1906. Aciivt poM.— Between Oalfano and Mayne ialanda. Bench-mark at )il Low-water datum at 18 feet 1 inch below a broad arrow cut on tha aouthem (ac Parson rock, in Minors' bay. This is a conapiouous angular block resting on ledge rock at the high-water line, about aOO yards north of the Engliah church, shore road passes immediately behind it, about 20 feet abore the krel of the bei Bench-mark at Qeorgina point; in the small bay on the south side of the p Low-water datum at 17 feet 9 inches below a broad arrow out in the perpi ndu f aoa of the rock about 20 yards eastward of the inner end of the boat wharf, bee I No. 8620. ... ^ J , Tidal obaervationa taken at Gcorgina point m the day time only, from Augu Ocwjer, in 1904. Oangu harlour.—ln Saltspring island. Low-water datum at 10 feet 3 ii below the top of the highest of the two drylag rocks situated in the small Iny ii diately weatward of the rooky poin fi-a which the wharf is built out boe l No. SOi^. South Ptnder.— On Pender island. Chart name, Bedwell harbour. Bcnchi a bro'^ arrow at the northern end oi the small bay north of Hay point l-ow' datum at 17 feet 11 inches below this broad arrow which ia cut in the face o rooky diff, above high-water maris. See Chart No. 2840. Tidal obserrations taken here in the season of 1906. H^ JriM AMO lUTUM PUMm «{th«bM«Mi. 8m Okut No. S««T. OmH r*^ Iw iWj O ■t U fMl • iMi.« Mow th* (op of <9tfMV/-lB North BMuiiaii diitriot, VuMwimr iiOaad. Lowir««M d«t«m at • tot Mow a bfood arrow of ohoM ooppor. ob ob iaoido pUo of tho now IMimv i^Mrf ; M t fu p oi idiii g to hdi^t of 1« foH 10 ia^M aboro tbo aill of tho ItnwlmaH diy Mb ■•• Chart No. IMOl ■ i ii