Under each ridge of the thick stratum of coarse gravel is laid a brick tunnel, built with cement blocks, and having some of the joints left open. The twofold object of this undulating structure is, that the filtered water may find its way through the open joints into the brick tunnels; and that the collection of the sediment in the intervening hollows of the undulating surface may facilitate the cleansing of the filters. The water flows from the reservoirs into the filters, where, by having to find its way through so many feet of shells, pebbles, gravel, and sand, it is separated from most of its mechanical impurities, and flows through the brick tunnels into other reservoirs.

The official statements of the number of houses supplied with water by the several London Companies, have not been given in detail in Parliamentary papers within the last few years; but we have compared the returns given at three periods somewhat wide apart. They are as follows:

of

The Hampstead Company's returns do not appear in any these documents. It has been estimated during the present year, that the number of houses now standing within the extreme limits of the metropolis, reaches nearly 300,000; of which between 70,000 and 80,000 are without any provision of water laid on within them. It is the condition of these 70,000 or 80,000 houses (as ascertained by "house to house" visits during the cholera period) which has mainly given rise to the present movement in respect to water supply; and it is unquestionably lamentable that those who have the most need of water are precisely those who are worst supplied with this necessary element. In respect to the total quantity supplied, the water-companies and the water-reformers always have differed, and still do differ, in their estimates. Dr. Roget, Mr. Brande, and Mr. Telford, who made investigations on the subject of the water supply in 1828, estimated the quantity at that time as follows:

Supposing this estimate to have been pretty nearly correct, the quantity must since have been largely increased-not only by the building of new houses, but by the greater attention paid to the subject generally. Mr. Wicksteed estimated the supply and consumption in 1845 at 45,000,000 gallons daily. As to the price at which this water is supplied, it varies so exceedingly under different circumstances, that hardly any trustworthy conclusions can be drawn. Where a district contains a good proportion of large houses, such as those that are supplied by the West Middlesex and Grand Junction Companies, the average charge per house is much larger than in poor districts, such as the East London or the Lambeth. But if we take the entries for 1833 we find that 277,5871. was received by the companies for supplying 191,000 houses, or about 29s. per house per annum. If we take the commissioners' estimate for 1828, and Mr. Wicksteed's estimate for 1845, to be correct, we may perhaps put down 34,000,000 gallons per day for 1833, which gave about 180 gallons per house, and for which was paid a fraction less than one penny per house per day. It is a convenient thing, for matters of comparison and memory, to bear in mind that the number of houses supplied, the total quantity of water furnished by all the companies, and the various rentals charged by them-all conduced in 1833 to give an average charge of about one penny a day per house, for all the houses supplied. In proportion as the average charge may have become during the last sixteen years, or may yet become in future years, a smaller fraction of a penny per house per day, so may we conclude that an advance is being made in the right direction; but the great variation in the sizes of, and charges for, different houses, renders such comparisons only approximately correct.

Before noticing any of the proposed changes in the water supply of London, it may be well to point out two recent legislative enactments, which have an important bearing on all new works of this nature throughout the country.

Under the provisions of the Act 9 and 10 Vict. c. 106, the Commissioners of Woods and Forests are empowered to make preliminary inquiries, in cases of application for Acts of Parliament for local improvements. Where such an application relates to the supply of water to a town, a surveying officer is sent by the commissioners to the locality, with powers to make a very minute examination of the whole question. He is first to investigate the existing supply of water, and prepare a plan of the town, the water works and aqueducts, and the geological structure of the district; then to give the number of inhabitants and of houses to describe the existing water works, and ascertain the number of wells and pumps; to determine the prospective capabilities of the existing works; the sunk capital; the annual expenditure, and the net income of the water works company (if any); the number of houses and buildings supplied and the rates charged; the extent to which there is any gratuitous supply by public fountains or pumps; and the chemical quality of the water so supplied. Having thus determined the nature of the existing supply, the surveyor

directs his attention to the proposed improved supply. He is required to ascertain the plans and sections of the new works; the mode of conduit from the same to the town; the quantity of water estimated to be supplied; the quantity which the exigencies of the town require; the chemical quality of the water; the necessity or not for filtration; the financial arrangements of the company by whom the new works are to be undertaken; and the rates proposed to be charged for the supply. The surveying officer reports on all these matters to the Commissioners of Woods and Forests; and the Commissioners report to the Parliamentary Committees, by whom the proposed Bill is investigated. The large body of trustworthy information thus obtained by disinterested parties, is calculated greatly to assist the committee in their decisions.

Until 1847, all Acts relating to water works were filled with numerous minute details which required to be repeated in each Act; but in that year a statute was passed (10 Vic. c. 17), for consolidating in one group certain provisions common to all the Acts, and for introducing certain improvements insisted on in respect to all supplies of water for towns.

In the discussions which have been carried on more or less continuously for the last quarter of a century, respecting the supply of water to the metropolis, the points which have been in agitation are, the amount of the supply, the quality of the water, the charge made for it, and the facilities for adapting the supply to a steadily increasing demand. Some of these points, it is supposed, might be settled by competition between various companies; but there are peculiarities in respect to the supply of water to large towns, which render it difficult to decide how far competition therein is advantageous. The experience of the south of London will illustrate this. The district south of the Thames has been mainly supplied (as we have before explained) by three water companies the Lambeth, the Southwark, and the Vauxhall. These companies all had occasion to apply to Parliament in 1834, for Acts which should give them increased financial powers; and in those Acts were clauses which seemed to throw out inducements for the companies to compete with each other in their respective districts. During the seven subsequent years the struggle became a fierce one. Double or treble sets of pipes were laid down in streets where one well-managed set would have sufficed; canvassers and commission agents were employed and paid for by all three companies to obtain tenants; plumbers were continually employed in changing the service pipes from one set of mains to another; paviours had quite a harvest in taking up and laying down roadways; treble sets of turncocks and pipe-layers were employed; and parochial and district rates were paid (in every parish where the competition went on) on all the pipes of all the companies, in proportion to the capital expended on them. By the year 1842 the consequences of the struggle became apparent. So great was the outlay compared with the income, that one company ceased to realize any dividend at all; while that of the other two was reduced to a very low rate, The competition ceased; and

each company was allowed by the other two to retain a district to itself. The rates were instantly raised to a point quite as high as they would have attained if there had been no competition; while the companies were unable to recover for many years the severe effects of the struggle.

There is unfortunately a great diversity of opinion among engineers and scientific men, as to which is the best quality of water, and which the most abundant, for the supply of the metropolis. Whoever has taken the trouble to wade through the Parliamentary Papers relating to this subject, will find sufficient evidence of this. The probable sources of supply are three-the river Thames; the small springs and rivers which flow into the Thames; and Artesian Wells. Dr. Bostock, Dr. Roget, Mr. Brande, Mr. Telford, Mr. Mylne, and a multitude of other persons whose names are well known in the scientific world, have expressed opinions so conflicting, that one side or other must be wrong; perhaps the truth lies midway between them all.

One class of new projects relates to the obtaining of water from a point so high up the Thames, as to avoid the pollutions of the London drainage. Dr. Arnott, many years ago, gave it as his opinion, that the water of the Thames, above the tideway, is excellently adapted for domestic purposes; and this idea has been the basis of many projects. Mr. Philip Taylor proposed a plan in 1824, for bringing water from a point between Brentford and Richmond, to a reservoir at Hampstead. Some of the later schemes have proposed to obtain water from the Thames at or above Teddington Lock; or to remove the lock now situated at Teddington to Richmond, and to take the supply from the portion of the river which would thus be cut off from the influence of the tide. Other projects have been planned from Staines and from Maidenhead; and in the spring of 1849, a Committee of the House of Commons was employed in investigating a project for a water supply from so distant a point as Henley-on-Thames. Vast as the scheme appears for an aqueduct of 34 miles (the amended plan), we may cease to deride it when we remember what Rome did with smaller mechanical means.

Those who prefer to look for a supply to the minor streams which flow into the Thames, rather than to the Thames itself, have directed their attention principally to the north-west parts of Middlesex. When Telford made his examination into this subject in 1834, he was guided by the fact, "that the water of the river Thames is strongly objected to by the inhabitants of this great city; and also condemned in the Report of the Commissioners of Water Inquiry (1828), in consequence of the impurities with which it is contaminated." Thus forearmed, it is no wonder that he sought for a water supply from other sources. He perambulated the district on each side of the valley of the Thames, and examined the streams which fall into that river in the vicinity of London. He proposed, that all the north-western part of London, then (and now) served by the Grand Junction, the West Middlesex, and the Chelsea Companies, should be supplied by the

River Verulam, near Watford; the water being brought to a reservoir near Primrose Hill. The south side of the river, served by the Lambeth, Southwark, and Vauxhall Companies, he proposed to supply from the river Wandle, near Beddington; having an elevated reservoir on Clapham Common. It was not proposed to supersede the six companies just named; but to compel those on the north side of the Thames to receive their supply from the Primrose Hill reservoir of Verulam water, and those on the south side from the Clapham Common reservoir of Wandle water. A government expenditure in connexion with the works, and an increased water-rate on the inhabitants served, were parts of the plan. With respect to the very large districts supplied by the New River and East London Companies, Telford recommended no other changes than such as could easily be carried out by the companies themselves; he considered the supply from the Chadwell, the Amwell, and the Lea, to be both salubrious and plentiful.

Many projectors abandon both the Thames and its tributaries, and advocate the sinking of Artesian Wells to the watery sandy strata which lie beneath the dense London clay. Mr. Paten, an engineer who was examined before the House of Lords' Committee in 1840, was one of many advocates of the Artesian Well system. He stated, that at that time there were 176 Artesian Wells in London, and that he had no apprehension of any failure in such supply; but that, yielding to an impression which had gone abroad, that new wells on such a scale as would supply water works would diminish the supply at the private wells, he had planned to sink his wells at some distance from London, and bring the water thence by means of aqueducts. He proposed to sink the wells at Bushey, near the river Colne; to use the Colne water as well as the well water; and to bring both to a reservoir near Saint John's Wood. Many plans, more or less similar, have been brought forward. Geologists, however, for the most part, discountenance this system, on the ground that the supply so obtained would be wholly inadequate. The Dean of Westminster (Dr. Buckland), at a meeting held at the Hanover Square Rooms on October 22, 1849, in relation to the Water Supply Question, expressed himself in the strongest possible manner against the Artesian Well plans. He said, that every additional well bored, has the effect of lowering the level of the water in neighbouring wells. It has indeed been long known, that Calvert's well at the Thames Street Brewery, and Barclay's well at the Southwark Brewery, affect each other so much—even though the Thames lies between them -that the two firms have made a mutual arrangement so that they shall not be pumping at the same time. Dr. Buckland asserted, that it is utterly impossible to supply the whole of London by Artesian wells.

A measure has been recently brought forward, for combining the various metropolitan parishes into a union, in order to enable them to work out the details of a better supply of water. The chief features of the project are the following:-A local committee to be