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 elevations. The north reservoir, containing 153,465 hogsheads of water, is 91 feet 10 inches above high water mark of the Thames. The south has a like relative altitude of 85 feet 10 inches, and will hold 139,921 hogsheads, while the 15 53 PRELIMINARY ESSAY. engine reservoir is only elevated 70 feet 10 inches, and holds 65,063 hogsheads. The water from the higher, can be let into the lower reservoirs. The water settles in these reservoirs, ' and, having deposited its sediment, passes off into the mains. 3,000,000 gallons are daily supplied to about 8000 houses by this company, of which two-thirds are delivered at heights varying from 90 to 110 feet, and the remaining third at from 110 to 150 feet above high water in the Thames. Of course, to effect this, resort is had to a steam engine, which elevates the water 61 feet 2 inches above that in the south reservoir. The East London Company, incorporated in 1807, succeeded to the old Shadwell Works, which used to supply the district north of the Thames, and east of the city. The capital at first deemed necessary was £100,000. Yet, within four years, nearly four times that amount was expended — a fact more or less true of each of the other companies — an'd upon which Matthews, in his Hydraulia, thus remarks : " whether it be an insurmount- able difficulty to form a statement, which in the first instance shall approximate to the real cost of a great undertaking, is a problem that yet remains to be solved." The water for this company was drawn from the river Lea. Four reservoirs were constructed on its banks, two on the east side, about 10 feet deep, so that their bottoms were on a level with the bed of the river, two on the west side sunk 5£ feet below the bed, and therefore 15 feet below the surface of the water at medium tide. The water flows into these reservoirs from the Lea, through eight channels, averaging 7 feet in width, but differing in depth, two being 4.6 feet deep, three 4 feet, and three 3.6 feet. An aque- duct under the river connects the reservoirs. In 1829, desiring to increase their supply of water, the company obtained an act of Parliament, granting them authority to draw water from Lea Bridge Mills, and to add £120,000 to their capital. The water supplied by these various works, is conveyed to the height of seventy feet by steam engines. About 45,000 houses are supplied with 170,000 barrels daily by this company, which has laid down between 2 and 300 miles of iron pipes, some of which cost 7 guineas per yard, or 21 guineas, equal to $105, for a length of 9 feet. The pipes vary from 36 inches to 6 inches, but are mostly of large calibre. The greatest distance to which the works extend, is three miles, and although the pressure at the engines is estimated at 120 feet, yet the resistance from friction usually pre- vents the water from ascending higher than 60 or 70 feet. The expenditures of this com- pany have been about half a million pounds. The south side of the Thames is supplied by two companies, the Southwark and the Lambeth, both deriving their supply of water from the river, pumping it up by steam power, and distributing it through iron pipes. PRELIMINARY ESSAY. The Southwark Company supplies about 7,000 houses daily with 1,500,000 gallons of water, on a capital invested of £66,400. The Lambeth Company, whose works are situated in the Belvidere Road, a short distance from Waterloo Bridge, supplies some 16,000 houses with 1,500,000 gallons. This company has incurred considerable expense, by constructing reservoirs on Brixton Hill, one at an elevation of 150 feet above tide — and two others at different and lower ele- vations, one of which was & filter er, and transmitted the water to the other much purified. One other enterprise only remains to be noticed — The South London Water Works, for which a charter was obtained in 1805. The principal establishment is on Kenning- ton Common, near Vauxhall, and, like the other works, it derives its