Two or three miles further a tributary enters the Severn, larger than any which it has hitherto received. This is the Vyrnwy, which drains a considerable area south of a watershed extending from near Aran Mowddwy to the Berwyn Hills, though now a heavy tribute has been exacted from its waters by the town of Liverpool. This great feat of engineering was completed, after years of labour, in 1890. Up to that time Liverpool had drawn its main supply from reservoirs on Rivington Pike. A huge dam, as our illustration (page 89) shows, has been built across the narrowest part of the Vyrnwy valley. It is 1,255 feet in length and 60 in height; the foundations, which at some parts had to be carried down to a depth of 50 feet, resting on the solid rock. By this means a lake has been formed, four miles in length, which hides beneath its waters--800 feet above sea-level--a little village and its church. A curious mound rises near the junction of the two rivers, designed, as some think, to guard the passage; and then the Severn, turning again to the east, passes on towards Shrewsbury. Its valley now has become more open: parks and country houses here and there dapple the gentler slopes within no great distance of the river, and the views of the hills are always beautiful. [Illustration: MOEL-Y-GOLFA AND BREIDDEN, FROM WELSHPOOL (_p. 87_).] [Illustration: _Photo: J. Maclardy, Oswestry._ THE VYRNWY EMBANKMENT, BEFORE THE FLOODING OF THE VALLEY.] [Illustration: _Photo: Robinson & Thompson, Liverpool._ A QUIET NOOK ON THE VYRNWY.]