DISTRICT MEETING AT THE SOURCE OF THE RIVER VYRNWY.

THE following general description of the Vyrnwy works is extracted from an account prepared on behalf of the Corporation of Liverpool, and published in connection with the ceremony of erecting the memorial stone at the commencement of the works on the 14th July, 1881 :

"At a distance of six miles to the south-east of Bala Lake, over the well-known Bwlch-y-Groes Pass (the Pass of the Cross) there is a long, narrow tract of valley land, at an elevation of 780 feet above mean sea-level, scooped out of the rugged mass of Silurian rocks by which it is surrounded, and evidently at some period the site of a natural lake, not unlike in its dimensions that of Bala. A geological ordnance map (on which the alluvial bottom is distinctively coloured) shows the resemblance very clearly. Into this valley there flow innumerable rivulets and brooks, which have their rise chiefly on the eastern and south-eastern slopes of the Berwyn range of mountains, and which unite to form the river Vyrnwy. In the centre of this valley stands the little village of Llanwddyn, consisting of thirty or forty small cottages, chiefly occupied by shepherds and farm labourers, a small church, and two Nonconformist places of worship. At Llanwddyn the valley attains a width of over half a mile, and then, following the course of the river, becomes narrower, until at a distance of two-and-a-half miles below the village its width at the narrowest part is not more than about 300 yards. Across this gorge, through which the Vyrnwy runs, the Corporation intend to construct an embankment, the total length of which will be 418 yards, and the top of which, measured to the water-line, will be about 84 feet above the present valley bottom. The effect of erecting this short embankment will

be to dam back the river so as, without any further enclosure than the natural valley sides, to form a lake which will be four-andthree-quarter miles long, with a water area at the surface of about 1115 acres. The surface area of Bala Lake is 1100 acres. The contents of Lake Vyrnwy, above the level at which water will be drawn off for Liverpool, will be about 12,000,000,000 gallons, which is one-third more than the storage capacity of the Loch Katrine works of the Glasgow Corporation. The embankment is to be built of masonry, and will be the largest work of the kind in this country. It will be spanned by arches carrying a road and footways, having a total width of 17 feet between the parapet walls. Any overflow from the lake will pass through the central series of arches and down the outer face of the wall. Thus the costly and troublesome weirs and byewashes of ordinary earth embankments will be dispensed with. The greatest width of the embankment at the base will be over 100 feet. For the discharge of the compensation water which the Corporation are bound to supply to the river there will be two tunnel outlets, with necessary sluices and appliances, through the embankment.

'It is not intended in this sketch to do more than indicate the general features of works, the details of which will be more appropriately described when they have been carried out. The area of the watershed, from which water would naturally flow into Lake Vyrnwy is 17,583 acres, and it is from this area only that it is proposed to collect and impound water in the first instance, but, as the demands in Liverpool increase additional water will be brought into the lake from two streams called the Cowny and Marchnant, which now fall into the Vyrnwy below the proposed embankment. These streams will be brought into the lake by tunnels respectively 11 and 13 mile in length. The Cowny and Marchnant will give an additional contributing area of 4,417 acres, making the total watershed of the lake, when all the works contemplated by the Act have been carried out, 22,300 acres. The water to be thus collected will be of the usual excellent quality derived from the Welsh hills. Previous to the application to Parliament for the Water Act of last Session, the water was analysed under various conditions of flood and drought by Dr. Frankland, Dr. Tidy, and Dr. Brown. Their reports were of the most favourable character, though chemical evidence is scarcely necessary where, as in this case, the watershed is so admirably adapted for the collection of water in the purest and best possible condition for potable purposes.

There is probably no district in Great Britain of equal area that is so thinly populated. There are no mines or mineral workings, and the only dwellings remaining will be a few scattered sheep-farms. The hills are precipitous and sterile, and the slate rocks of which they are composed throw off the rainfall with great facility. The Vyrnwy has long been celebrated for the excellence, variety, and abundance of its fish. Pennant wrote that the river merited the title of Piscosus Amnis as much as any he knew.

"The aqueduct for conveying the water from Lake Vyrnwy to Liverpool will be formed partly by tunnelling and partly by castiron pipes. Where the aqueduct is in tunnel it will be made of sufficient capacity to convey as much water to Liverpool as the lake will be capable of yielding, but where pipes are to be used it is intended to lay, in the first instance, only one pipe, which will be large enough to deliver about one-third of the calculated total yield available for Liverpool from the watershed. The aqueduct will commence at the lake by a tunnel about seven feet in diameter and two-and-a-quarter miles in length, starting from the north side of the Vyrnwy valley, and terminating in the Hirnant valley. From the outlet of the tunnel a cast-iron pipe of about 42 inches internal diameter will be laid through the Hirnant valley across the river Tanat, and to the north of the village of Llanrhaiadr-yn-Mochnant, near which place the first section of the pipe line will terminate in a small reservoir or relieving tank to be constructed at Parc Uchaf. Thence it will be laid through the parish of Llansilin to the valley of Cynynion, on the borders of Denbigh and Salop counties, whence a tunnel of about one mile in length will be driven to the west side of the Morda valley. There will be a raised aqueduct over the Morda river, and from the east side a second tunnel of one mile long, terminating in a small reservoir to be formed on elevated ground about a mile to the west of Oswestry. At this point filterbeds are to be made if filtration should be required. From Oswestry the cast-iron main proceeds in a north-easterly direction through the parishes of Whittington and Ellesmere, Hanmer and Malpas. In Malpas there will be another relieving tank on Oat-hill. Thence the pipe will be continued through Bunbury and Beeston, passing at about a mile to the east of Tarporley, to a relieving tank on Luddington Hill; thence through Delamere Forest, and under the river Weaver, near Kingsley ford, through Aston, to a tower to be erected at Norton. From the Norton water-tower the main takes a northerly direction to the Mersey, which it crosses at a point

two-and-three-quarter miles to the east of the Runcorn viaduct. After crossing the Mersey the pipe follows an almost straight line through Farnworth and Rainhill to the existing reservoirs of the Corporation at Prescot, near Liverpool. The total length of the aqueduct from the Vyrnwy to Prescot is 67 miles, but the distance from the Vyrnwy to Liverpool in a direct line is only 46 miles.

"The River Vyrnwy is at present subject to great fluctuations in flow. After the lake has been made the Corporation will have to send down the river the statutory supply of compensation water, which, being delivered in a steady, regular, and constant stream, instead of the present irregular flow, will be a great improvement to the river, and a great advantage to the residents on its banks. The total estimated yield of Lake Vyrnwy watershed, including the compensation water, is estimated at 52 million gallons per day. The Engineers for the works are Mr. Thomas Hawksley, of London, and Mr. George F. Deacon, of Liverpool, under whose superintendence the drawings and specifications are to be made and the works to be carried out.

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"When the works now being inaugurated have been finished, Liverpool will possess the finest supply of water of any city in the world. In the Rivington and Vyrnwy watersheds, and the new red-sandstone wells, the Corporation have the means of supplying a population of more than 2,300,000 with a constant supply of unexceptionable water. The population at present supplied by the Corporation according to the recent census, is 720,000. If it continues to increase as it has done during the last decade the population will, at the end of the present century, amount to more than a million. In addition to this the Corporation have agreed to supply water to the towns of St. Helens, Widnes, Warrington, and Oswestry as soon as the Vyrnwy water reaches Liverpool."

When the visit of the Association took place the building of the masonry embankment had already been commenced at the deepest part of the excavation for the foundations. The rock for a width of more than 100 feet had been exposed across the valley. It exhibited glacial smoothing and striations nearly parallel to the axis of the valley, and similar striations are observed at various points on both sides of the proposed lake to its head, nearly five miles beyond the embankment, and at even more distant places near the beds of tributary streams. It was stated by Mr. Deacon that the shafts, borings, and probings, made for the purpose of determin

ing the best site for the embankment, had revealed the fact that higher up the valley as well as lower down, the rock became rapidly deeper. This circumstance and other geological observations point to the conclusion that the valley was scooped out of the rock by glacial action, probably, like many other glacial valleys, to a great depth. Near the site of the proposed embankment the glacier on its course down the valley was squeezed by the converging mountains to a comparatively small width, and coincidently, was prevented from wearing the bottom so rapidly and so deeply as higher up the valley, by bands of the hard volcanic rock known as Bala Ash. As the glacial age passed away, and the frozen streams became running water, the basin, scooped out by the glacier, must have become the site of a lake some 50 feet below the present level of the valley, this being the level of the rock near the embankment protected by "Bala Ash" over which flowed the ancient river from the lake. At this time the rigour of the glacial age had not all disappeared, denudation by frost and rain produced great effects in a short time, and, much sooner than would now be the case, the lake was silted up with gravel and sand brought down in flood by the tributary streams, and by the same agencies the valley has been filled up apparently almost level throughout its length, to a height of about 50 feet above the former lake. Through the alluvium and peat winds one of the principal tributaries of the Severn, the modern river Vyrnwy. Even now, however, in time of flood the valley assumes the aspect of a lake but little above which, on a delta at the mouth of the effluent river Cedig, stands the village of Llanwddyn. The level of the new lake, to be created by the presence of the great masonry embankment now being constructed, will be some 130 feet above that at which its ancient prototype probably lay.

The members present, after viewing the works, and especially the rubble masonry, in which stones up to 6 tons weight are being used, drove up the valley to an old farm-house near the head of the proposed lake, known as Rhiwargor, from the hill behind which a magnificent view down the valley was obtained. Hence the members drove to another branch of the valley, and visited Eunant Hall, an old shooting lodge, from which this remarkable, and hitherto almost unknown part of Britain was also viewed.