2 ELECTIOXS, ETC. [Minutes of Associate ilIembem-continued. JAXESDICEERSOW HUYPIDGE. l FI:A.NI~WALTER SCOTT, Jun., Stud. Inst. JAMESROUTLEDGE JACQUES. l C.E. CHARLESVEREKER LLOYD, A.K.C., ~ ALBIOXTIIOMAS SXELL. l Stud. Inst. C.E. TV.4LTER JOHNSTAYFORD, B.A., B.E. WALTEREDWAED MAY, Stud. Inst. C.E. i JOHXHODGSOX SUAI~T. CHARLESMURRAY, Stud. Inst. C.E. ALLANARCHIBALD CAMPBELL SWINTOX. HARRYPEKX, Stud. Inst. C.E. WILLIAXHEXRY THORPE. LESLIEHUNTER REYNOLDS. ARTHCR WILLIADISOS, Stud. InSt. C.E. LIOWELSALTXARSHE. GEORGEWYLIE, F.C.H. , Associate. Ncbjor LEAXDROCUBILLO. (Paper No. 2433.) Recent Dock Extensions at Liverpool, with a General Description of the MerseyDock Estate,the Port of Liverpool,and the RiverMersey.” By GEORGEFOSBERY LYSTER, M. Inst. C.E. THEspecial characteristics of theRiver Mersey, theimportant positionwhich Liverpool occupies among theleading trading centres of the world, and the rapid development of its commerce are, each and all, so interesting to engineers, that in submitting a Paper descriptive of the most recent dock extensions carried out in the port, the Author has been induced to touch upon each of these points, as a fitting preamble to the more formal and precise description of the special works which form the leading features of the Paper. Few, if any, localities, inthis country at all events, are so favourably situatedfor the construction of a comprehensive system of docks as that of Liverpool, not onlyby reason of its geographical position on the seaboard of the country, with its unrivalled water frontage, but also on account of its proximity to the great manu- faeturing districts, as well as to the coal and mineral fields of the North of England and Wales, with which it is linked by railways and canals, which aresuch important factors in thedevelopment and maintenance of successful trading. Sucha combination of advantages could notfail, if properly dealt with, to makeLiverpool a greatport, and this is clearly demonstrated by the continuous advance in its trade and revenue since it was a mere fishing village, until now, when it stands in Downloaded by [ University College London] on [20/09/16]. Copyright © ICE Publishing, all rights reserved. Pmeecliws.1 LPSTER ON DOCK EXTENSIONS AT LIVERPOOL. 3 the very foremost rank of the seaports of the world. In 1800, the vessels trading to Liverpool during the year numbered four thou- sand seven hundred and forty-six, of 450,060 tons register, and brought in a revenue from dues of ,523,380 to the Municipality, to whom the docks thenbelonged; whereas inthe financial year ending the 30th of June, 1889, the total number of ships entering was twenty-two thousand six hundred and sixty-two, of 9,292,000 register tons, producing a revenue from dues of ~€990,550to the Dock Board. Withoutentering minutely into a description of the Mersey and its characteristic features, it may be stated that the entire length of the river bearing that name is 56 miles. It rises in the ,Derbyshire hills on the borders of Yorkshire and Cheshire, and the general direction of its flow for the first 37 miles, that is until it reaches the town of Runcorn, is westwardly. Down tothis point it is an ordinary river withparallel banks, having a tortuous course through an agricultural countrychiefly of the Red Sandstone .formation. At RuncornGap it intersectsthe RedSandstone “ bluffs.” Here it takes a sudden bend, nearly at a right-angle to its upland course, and expands into a shallow estuary from 2 to 3 miles in width, following a north-westerly direction to the sea, which it enters at NewBrighton. For the last G miles of its course, along which the city of Liverpool is situated on its right bank, and the town of Birkenhead on its left, with their several systems of docks, the riverbecomes contracted, and at itsnarrowest point, opposite the centre of Liverpool, its width is only a little over 3,000 feet. Its shores, on each side, risegradually inland, and afford excellent shelter fromt8he prevailing minds. It will thus be seen that, from Runcorn to the sea, the Mersey is of a shape which has been aptly described as that of a “bottle,” of whichthe wide expansebetween :Runcorn and Liverpoolforms the “body,” and the 6 miles of “ narrows,” opposite Liverpool, the ‘‘ neck.” Between its source and the townof Runcorn, the Mersey receives several tributaries, the principal being Tame,the Irwell, andBollin, on the second of which, at about 8 miles from its junction with the Mersey, is situate the cityof Manchester. Thetotal area of countrydrained bythe river to Woolston weir, a point about 5 miles above Warrington, is about 750 square miles. Below Warrington, no considerable stream joinsthe Mersey until the town of Runcorn is passed, a mile below which the Weaver, a veryimportant tributary, discharges its water into the estuary B2 Downloaded by [ University College London] on [20/09/16]. Copyright © ICE Publishing, all rights reserved. 4 LYSTER ON DOCK EXTENSIONS AT LIVERPOOL. Winutes of from the left bank, its junction and generaldirection being nearly at a right-angle thereto. This river has its source in the southern portion of Cheshire, and, with its tributaries, drains a great part of the centre of the county, the area of its catchment basin being about 550 square miles. These rivers, with other minoraffluents of the Mersey, bring up the total area of its drainage basin to about 1,724 square miles. The rainfall within that area varies in different localities from 25 to 53 inchesper annum. The upland water discharged into the estuary is computed at from 2,000,000 to 3,000,000 cubic yards in twelve hours. The highest point on the Mersey reached by the tide isWoolston weir, and to this point only extreme spring-tides flow. PITeap-tides do not reach a higher point than “ Fiddler’s Ferry,” about 5 miles belowWarrington. On theRiver Weaver ordinarytides reach Sutton weir, near Frodsham, about 2 miles from the junction with the Mersey. Thetidal water passing in andout from the sea, through the channel abreast of New Brighton, has been estimated at 710,000,000 cubic yards on a high spring, and 281,000,000 cubic yards on a low neap-tide. Compared with these figures, theamount of uplandwater appears insignificant, yet combined with the tidal flow and ebb, it plays a most importantpart in maintaining the regime of the river, and counteracting the processof silting which iscontinuously going on throughout the estuary. The total tidal area of this estuary, within the lnouth cif the river at New Brighton, is 22,500 acres, the greaterportion of which, between Runcorn and the narrows at Liverpool and Birkenhead, is filled with a deposit of sand, 17,300 acres being abore the level of low-water of spring-tides. Through this vast extent of sand the upland water, when the tide issufficiently low to permit it,ploughs its way and forms a channel for itself in its course to the sea. The direction of this channel is never constant for any length of time, and by its incessant wanderings through the wide estuary permanent accretion is prevented. On this peculiar feature no doubt the maintenanceof the Mersey as a great tidal receptacle mainly depends; and were any stoppage or interference with the roving tendency of the low-water channel riermitted, permanent accumulation must takeplace, and the growth of solid land, to the exclusion of acorresponding bulk of tidal water, would be the inevitable result. The importance of this fact csnnot be too stronglyurged, as it is i~ universally accepted opinion, by competent authorities, that any Downloaded by [ University College London] on [20/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] LYSTE~ON DOCK EXTENSIONS AT LIVERPOOL. 5 extensive exclusionof tidal waterfrom the estuary must injuriously affect the sea-channels, and finally destroy the port of Liverpool. The deep-waterchannel of the Merseycommences below the upper estuary, with the contraction of the river at Dingle Point, where it is 7,200 feet in width. It extends in a northerly direction in a fairly straightline, to the mouthof the river at New Brighton, where it is about 5,600 feet wide, though at an intermediate point opposite the centre of Liverpool, as before mentioned, the width is only about 3,000 feet. For thewhole range of this portion of the Mersey, there is plenty of water for vessels, the depth at low-water of spring-tides being about 40 feet at the Dingle, 50 feet at Seacombe, and 70 feet abreast of New Brighton.These depths are always fully main- tained, as the tides run with great rapidity through the narrows,’ the velocity at springs being 6 to 7 knots an hour. The immediate foreshores of this deep ” have a sandy fringe, which towards its southernextremity, on t,he Liverpool side, assumes a projection of considerable and inconvenient proportions, known as the Pluckington Bank, the existence of which is mainly due to thedeflection of the ebb currents to the Cheshire shore, by the rocks at Dingle Point. Along the whole of this reach ’’ the anchorage is good, so that vessels of the largest size lie moored with safety in anyweather. Upwardsfrom the southern extremity of the Dock Estate extendtwo well-defined channels, one on the Lancashireside being navigable for vessels of light draught as far as Garston, the other on the Cheshire side as far as Eastham. The latter, knownas the Sloyne, is for the greater portion of its length wide and deep, affording excellent anchorage for all classes of vessels, including the oldmen-of-war now used as school and reformatoryships. The Cunard steamships also have long moored in this position, while fleets of sailing coasters, waiting for suitable weather, make it theiranchoring ground; as many as one hundredand fifty vessels may frequently be seen lying there at thesame time.