400 miles laid down of wooden tubes, of which about twenty miles, on an average, required to be renewed every year, thus causing the whole to be renewed every 20 years. This was a monstrous annual drain, besides the public incon- venience of constantly breaking up the great thoroughfares to replace these tubes. The smallness of the bores, moreover, of the tubes, seldom exceeding eight inches, required a great multiplication of trains to transmit the needful supply of water. In 1810, nine trains were laid side by side in one street. In the course of the next ten years, all the wooden tubes were replaced by iron, at a cost of one and a half million dollars. In addition to the supply from the New River, this company, in fulfilment of their contract with the London Bridge Water Works Company, have a steam engine of 100 horse power on the banks of the Thames, between Blackfriars and Southwark iron bridge, which, through a main 33 inches in diameter, extending into the river, can pump up 5000 hogsheads per hour ; so as in any contingency to ensure a supply to those families deriving water from the Bridge Company. This engine, however, though always ready for use, is not used. The present capital of the New River Company, in amount actually expended, is about £1,250,000, or six and a quarter millions of dollars. The Chelsea Water Works were next established, an4 by act of Parliament in 1723, the Company was incorporated. The works are situated at the' north-east part of Chelsea reach, on the banks of the Thames, whence all the water is derived. It is now pumped up by two steam engines into the reservoir, whence, after passing through a filtering bed, occupying nearly an acre, and filled with gravel and sand, and capable of clarifying daily, 2,240,000 gallons, it is dispensed to the consumers. PRELIMINARY ESSAY. 57 This company distributes daily over 2,000,000 gallons, to about 13,000 houses, and can raise it 128 feet above the level of the Thames. The cost of this work, with its improved filtering system, was about £70,000, or $350,000. The West Middlesex Works, after the lapse of nearly a century since the erection of the Chelsea Works, were completed in 1811. They are situated on the north bank of the Thames, near Hammersmith, and about nine and a half miles from London Bridge. The whole water is procured from the river by conduit pipes of 36 inches diameter, extending into the channel of the river. It is pumped up by three steam engines, one of 105 horse, the other two of 70 horse power each, into two capacious reservoirs — one at Kensington, 122 feet above the low water of the Thames, the other at Barrow Hill, 188 feet above the same level. The Kensington reservoir is 309 feet long, 123 wide, and 20 feet deep. The Barrow Hill reservoir will contain 88,000 hogsheads. This lofty receptacle, with its mains and appendages, cost $300,000, and supplies the houses around Regent's Park. The utmost distance to which the water is conveyed from Hammersmith is about 10 miles ; the number of houses supplied exceeds 15,000, with an average daily quantity of 150 gallons of water. The cost of these works exceeds two and a half million of dollars. The Grand Junction Water Company was authorised by act of Parliament, in 1798, but was not undertaken until 1811, when a subsidiary act having been passed, in- corporating separately from the Grand Junction Canal Company, the persons who were to construct the water works, the scheme, amid many difficulties, of which the chief was want of money, was carried out, and a sum of £312,000 was expended therein. At first the supply of water was derived from the Grand Junction Canal, which was fed from the rivers Colne and Brent, and from a large reservoir of nearly 100 acres, filled by the various streams of the vale of Ruislip, in the north-western part of Middlesex. The quality of this supply was complained of, and, moreover, as the sphere of operations of the company was extended, the quantity abstracted from the canal became a source of inconvenience to its trade. An effort was made to substitute the waters of the Regent's Canal for those of the Grand Junction, but the quantity was quite insufficient, and there- fore the unfailing Thames was resorted to, and from its exuberant bosom has been drawn ever since 1820, the whole supply of these works. Their steam engines, two of 100 horse power each, are erected at Chelsea, between the Royal Hospital and the Chelsea Water Works. From mains laid into the channel- way of the river, they pump up water into three spacious basins, at Paddington, each of different dimensions and