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THE NEW WATER SUPPLY OF LIVERPOOL.

BY JOSEPH PARRY, M. INST. C.E.

IF I had been free to select a subject upon which to address this Literary and Philosophical Society, my thoughts would have been directed as far away as possible from waterworks and their associations. But our esteemed President was of opinion that it would be of interest to the members if I would describe to them some of the special and distinctive features of the new Vyrnwy waterworks, concerning which so much has recently been heard, and which affect so closely the welfare of Liverpool. I felt it to be a duty as well as a pleasure to endeavour to comply with his wishes.

According to the constitution of this Society, one of its objects is the "study and promotion of Science and Fine Art." Both from a scientific and artistic point of view, there is undoubtedly a great deal that is deserving of study and suggestive of discussion in connection with these works.

Singularly enough, and quite unexpectedly, I appear before you on the very day upon which the newspapers contain an account of the opening of the Thirlmere works of the Manchester corporation, which resemble very much the Vyrnwy works in the character of the watershed, the quantities of water provided, and the distance between the source of the supply and the point of delivery and distribution. Both schemes also afford striking evidence of the growth and enterprise of the great cities by which they have been carried out, and of the difficulty of procuring

water in sufficient quantity, and of sufficient purity, to satisfy the demands of health and trade and the requirements of modern science. Another great communityBirmingham-has recently commenced works of a similar character on the upper tributaries of the Wye, also in North Wales, and with a watershed resembling in all respects very closely the watershed of the river Vyrnwy.

In the summer of the year 1684, Henry Somerset, Duke of Beaufort, who was then president of Wales, and lord-lieutenant of several neighbouring counties, undertook one of those official tours in which he represented the majesty of the throne with a pomp scarcely inferior to a royal progress. He reached Bala, in Merionethshire, on the 29th July. He was welcomed by the loyal gentry of the county, and "plentifully entertained" by Col. Price, of Rhiwlas. After inspecting the militia, he resumed his progress to Llwydiarth, in Montgomeryshire, and thither, from Bala, the chronicler tell us, "the nighest way you are directed by guides, by reason of dangerous boggs in the passage after the precipitous ascents and descents near Bala. Seven miles from Bala, and within four miles of Lleudar, we passed by Llanwddyn church, leaving the churchyard on the right hand, at which place they expressed their loyaltie and good affection toward his grace by jangling of their little bell, of which they spared not, the strangeness of the noise whereof caused me to enter therein."

This is the first record which I have been able to find of a visit to Llanwddyn.

Nearly two centuries later, in the year 1865, the peace of this remote village was disturbed, and the curiosity of its inhabitants excited, by the appearance of a stranger who, after spending some time in exploring the valley and

streams, caused to be placed in one of the fields adjoining the village a copper cylinder, some four feet long by eight inches in diameter. The stranger was a civil engineer from Westminster, who was preparing a scheme for supplying the Metropolis with water from the upper sources of the Severn, and the mysterious cylinder was simply a rain gauge, placed in the valley for the purpose of ascertaining the amount of rainfall that could be collected.

Mr. Bateman's scheme was submitted to a royal commission on water supply, which sat during the years 1866-67, under the presidency of the Duke of Richmond. The commissioners did not report in favour of carrying out any of the gravitation schemes which they investigated.

Ten years later, the upper waters of the river Vyrnwy were suggested as being suitable for the supply of Liverpool, and after an exhaustive comparison between the Vyrnwy and other projects which had been previously proposed, the Vyrnwy scheme was adopted, and application was made to Parliament in the session of 1880 for the necessary powers to carry it out.

In selecting a river as a source of supply for a large community like Liverpool, the first question to be considered is, whether the watershed or gathering ground from which the water is to be collected is of such a character as to yield, and to continue to yield, water of a quality suitable for domestic and trade purposes. Freedom from liability to pollution by sewage is of course of the very first importance, but this is not the only risk to be kept in view. There are such things as mining operations, peat bogs, and other contaminating influences which may make a watershed unfit or at least unsafe as a permanent source of supply. An ideal gathering ground

would consist of uninhabited granite rocks, without any covering of soil or vegetation.

Assuming the quality of the water to be satisfactory (and as evidence of this I attach more importance to the physical characteristics of the watershed than to a chemical analysis), the question then arises, whether the quantity of water available is sufficient for the needs of the district to be supplied; not only for immediate and immediately prospective requirements, but capable of expansion to meet any demands which can reasonably be anticipated in the future. It is also desirable that the rainfall should be heavy, so that the volume of water available may be large in proportion to the area of the land to be drained. Having found a satisfactory watershed of sufficient area and with an adequate rainfall, it then becomes necessary to ascertain if there is a suitable site upon which to construct an impounding reservoir of the required capacity. The valley or basin which is to be the site of the future reservoir must be absolutely water-tight in every direction, and, above all, there must be a solid, impervious, foundation upon which to build the wall or embankment by which the waters are to be held back.

Assuming all these conditions to be met with, there are yet other conditions to be fulfilled. One is that the elevation of the watershed shall be such as to permit of the water flowing by gravitation into the houses of the persons to be supplied. Another is that there shall be a practicable route along which an aqueduct can be constructed without involving engineering works of a very costly character. A final condition, which governs all, is that the total amount of expenditure required to carry out and complete the undertaking shall be reasonable, and not altogether disproportionate to the benefits to be conferred.

Now, in the Llanwddyn Valley, all the conditions