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THE BARRY DOCK WORKS,

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THE BARRY DOCK WORKS, INCLUDING THE HYDRAULIC MACHINERY AND THE MODE OF TIPPING COAL, BY JOHN ROBINSON, M.INST.C.E., RESIDENT ENGINEER OF THE BARRY DOCK AND RAILWAYS COMPANY. [Published by Special Permission]. fc' (CONTINUED FROM LAST WEEK.) METHOD OF EXECUTING THE WORKS. The tide had first to be excluded from the site of the dock and quays, upwards of 200 acres in extent, a somewhat dimcultproceeding on account of the great tidal range of the Bristol Channel. This was done by Putting three dams across the channel between the Mainland and Barry Island, the two outer dams in- cluding the whole of the site required for the actual dock works. The intermediate dam was the first to be closed; and the only trouble experienced was the sinking of the earth into the mud, necessitating the frequent raising of the embankment tips. The closing of the second dam, at the western end of the dock, !ias very difficult, owing to its resting on mud varying in depth from a few feet to upwards of 40 feet. The first portions were made at each end, by tipping earth from wagons run out from the mainland and island; but, on reaching the deep mud, owing to the earth Buiking into and sliding away with it, a timber pile viaduct was constructed across the gap, on to which the loaded trucks were run and the earth cast out, thus forming the dams in layers. This method was Persevered in until, as the two ends approached each other, the tidal current became too rapid. Two un- successful attempts were then made by the contractor to close the gap with earth at low-water neap-tide, the intention being to exclude the tide of the day at low Heaps, and then to raise the bank each day above the Increase in height of the tide. In spite of every effort, the water gradually gained upon the work, and Washed the earth inwards, leaving a gap 80 feet wide, through which the speed of the tide was nearly five miles an hour. The method, originally proposed by the engineers, of dropping down shutters between Walings, securely fastened to the viaduct piles, after the tide had receded, was now resorted to. The shutters were backed up with a large quantity of stone, together with earth, as rapidly as all the avail- able trucks and wagons, which were standing full, could be brought forward. In this manner the tide Was excluded from the western portion of the dock Works in July, 1885. A 40-inch cast-iron pipe had been laid through the dam, and rested on a timber Platform on the mud. A flap on the outside was closed against the rising tide, and opened when it Receded, thus allowing the water left inside to be gradually lowered to the level of the sluice, and the Excavation above that level to be proceeded with. The remainder of the water below the pipe was removed by pumping. The eastern dam remaining to be closed had been toade partly of permanent, and partly of tempoiary, masonry, founded on marl and backed up with earth. To close it, piers of masonry were built, leaving four 15 feet openings, through which the tide flowed, until the openings were rapidly closed with planks, backed with concrete made with blue-lias lime and Portland cement, in March, 1886. The planks were afterwards removed, and the concrete was faced with brickwork 111 cement mortar. To drain away any water accumu- lating at this end of the dock, three 12-inch pipes, with valves, had been laid through the bottom of the concrete wall, at its lowest part. Excavation was then proceeded with inside this dam, above the level of the three sluices. To drain the water from the excavation for the dock below the level of the temporary sluices, a sump, 20 feet in diameter, was »*mk 10 feet below the bottom of the dock at the uorth-west end. From the sump a heading was driven, 160 yards in. length, into the corner of the dock. All the water which accumulated between the intermediate and western dams flowed along channels to the comer of the dock, thence through the heading to the large sump, and was pumped by a Cornish engine along a wooden shoot, over* the western dam, into the harbour. The engine had been remove3 from the Severn Tunnel works, and was capable of lifting 270.000 gallons per hour; but 150,000 gallons was about the average pumping required. To drain the excavation between the eastern and intermediate dam, another sump was sunk near the entrance, in which were placed two T bob pumps, which discharged the water over the eastern dam into the sea. When the water was excluded from the site of the dock, between the western and central dams, borings Were made to ascertain the exact nature of the strata Underlying the dock, which had already been found to be disturbed by faults. These indicated the necessity of setting back the south side of the dock, and of altering the position of the entrance. The excavation for the dock was carried out In Various ways, steam-navviea and grabs being ex- tensively employed. The steam-navvies, when in Regular work, excavated, in a day of ten hours, 500 Cubic yards of marl, loosened with powder, and in Softer material, such as stiff mud or clay, 1,000 cubic yards. For excavating mud from trenches in which Water lay, steam-grabs proved the most useful; for lifting rock, portable steam-cranes, with iron skips, were employed. All hard materials for the excava- tion were utilized for embankments and quay roads *ound the dock; and the mud was deposited at the back of these, and in trenches for making the works Water-tight. Special side-tipping wagons, designed by the contractor, were used for tipping the mud and *ilt. The earthwork being well advanced, masonry Was commenced in the dock. The lower portions of the basin walls were built in trenches, cut in the marl and magnesian limestone, before the completion of the excavation forming the basin. For transporting the material, there were thirty locomotives, exclusive of those working on the railways north of the dock. When the work was in full progress, about three thousand men were engaged. During the summer and autumn, the work was carried on also at night, temporary electric and Wells' lights proving ex- tremely useful. The dredged material from the Entrance channel was carried out several miles to sea, m hopper barges. A caisson was erected at the sea face of the >. entrance, inside the temporary stone dam. It fitted Against the quoins of the entrance, and enabled the temporary stone dam to be removed before the works were wholly completed. On the 29th of June, 1889, Water was first admitted into the basin and dock by opening the sluices in the 10-foot culvert at the entrance, on a rising tide, the outer gates being closed, I\nd. the caisson, in position, resting on the keel-blocks against the quoins. The sluices in the culvert at the West end of the dock were also opened. At that tide the basin and dock were covered with five feet of water at the next, with 18 feet; and at the following tide with 23 feet. The water between the entrance Kates and caisson was allowed to flow inwards and awards at each tide, through the sluices in the V,lt as aoon as the height of the tide exceeded anriWater in the dock, the caisson sluices were closed, 0?^ opened again whan the tide receded. On the 13th Jf/y, 1889, the caisson was floated a draught x feet of water, and was taken into the basin by a and the tide admitted freely to the dock. BREAKWATERS. The breakwaters are formed of rubble, excavated fom the basin and railway cuttings; and the sea is protected by blocks of mountain limestone, ot «"om four to seven tons. The eastern breakwater is ?,600 feet long the western breakwater, 700 feet long, with the island by a light timber viaduct. ■The sea slope of the breakwater varies from 3 £ to 1 at the toe, to 1 to 1 at the top; and the inner slope is l £ to 1. The width of the breakwaters, 8 feet above high-water of spring-tides, is 20 feet; and above this a rough parapet, 12 feet wide and 5 feet high. The great rise of the tide renders it necessary that the breakwaters should be substantial works they are, at the deepest part, 46 feet in height, and 200 feet in Width at the base. The rubble hearting was deposited from wagons and the large blocks were brought in trucks from a quarry five miles away, and placed in Position, on the eastern breakwater, by a 10-ton Scotch crane, and on the western breakwater by a crane fixed on a floating barge. The ends of the breakwaters are vertical, and consist of creosoted timber pilework, 32 feet wide, the intervening space being filled with stones roughly packed by hand. There are seven compartments in each breakwater head, with vertical rubbing pieces on the inside, so as to permit the subsidence of the hearting without damage to the framing. [To BE CONTINUED.]

.DEATH OF A GLAMORGANSHIRE…

CONSERVATISM AT CADOXTON-BARRY.…

CARDIFF HORTICULTURAL SHOW…

CORRESPONDENCE.

SECOND CLASS SEASON PASSES…

WHY NOT USE THE BATHING MACHINES…

SHARP PRACTICE AT CARDIFF…

BARRY DOCK TIDE TABLE FOR…

FORTHCOMING REGATTA AT BARRY…

MESSRS LAURIE AND JOHN'S ENGINEERING…

BISHOP BARRY IN NORTH WALES.

SHIPMENTS FOR LAST WEEK.

NARROW ESCAPE OF BARRY SAILORS…

SHIPPING AND TONNAGE FOR THE…

ANNIVERSARY DINNER AT CADOXTON-BARRY.

FATAL ACCIDENT AT BARRY IDOCK.

SERIOUS ILLNESS OF MR. DAVID…

LOCAL APPOINTMENTS AT THE…

BARRY AND CADOXTON LOCAL BOARD.

DINAS POWIS NATIONAL SCHOOL.

LONDON AND PROVINCIAL BANK.…

Barry Dock Shipping / Intelligence.

VESSELS ENTERED OUTWARDS.

VESSELS CLEARED.

BARRY MEN IN TROUBLE AT CARDIFF.

ARTILLERY VOLUNTEER INSPECTION…

-PORTH.

ICADOXTON AND BARRY BURIAL…

TRADES UNIONISM AT CADOXTON-BARRY.

Family Notices

VOLUNTEER INTELLIGENCE.