550

HISTORY OF ENGINEERING.

Rook T.

The mode of filtration is by the descent of the water, which, in its way, is made topass through fine and coarse river sand, broken shells and pebbles, and small and largegravel. These several materials are laid in a reservoir, disposed in ridges, which show anundulated surface ; and the whole depth of the beds is about 5 feet. The upper layeris fine sand, the second coarse sand, the third pebbles and shells, the fourth fine gravel,and the fifth large gravel; built within these with cement blocks are eleven brick tunnelsfor collecting the filtered water, partially open-jointed, with spaces of 1^ inch on the bed,with the heading joint of each brick also open.

The bed of the filtering works consists of loam, sand, and gravel, which overlie theLondon clay to the depth of 30 feet; the two latter strata contained powerful land springs,so that it was necessary to form a bottom with clay and cement walling. The bed coversan area of an acre, and there is an elevated reservoir of nearly the same size.

* 'The water is let in by nine brick tunnels, and the ends of the pipes are fitted withcurved boards to diffuse the currents of water, and prevent the surface of sand from being dis-turbed ; this is scraped every fortnight, and from a careful examination, it appears that thesediment penetrates to the depth of from 6 to 9 inches, to which depth the sand is frequentlyremoved, and fresh supplied by carefully lifting portions in succession. The quantity ofwater filtered is from 300,000 to 400,000 cubic feet daily, or 2,300,000 gallons. The costof the filter, exclusive of the land, was 11,700/., and the annual expenditure for raising thewater on the filtering bed is 800/., for cleansing and renewal a similar sum. A steam-engine of 120 horse power raised, in the year 1834, 4,G40,000 gallons of water per day, aportion of which was carried to the height of 135 feet : 13,892 houses were supplied inthe year with 15,750 hogsheads of water.

The West Middlesex Water-works were established in the year 180C, and arc situated onthe banks of the Thames at Hammersmith ; they obtain their supply by means of steam-engines, the power of which is equal to raising 6,000,000 gallons per day to the height of122 feet; the water is pumped into a reservoir at Notting Ilill, and another at PrimroseHilL

The number of houses and buildings supplied are 16,000, and the total quantity ofwater annually is 20,000,000 hogsheads ; the average daily consumption 2,250,000 gallons,or about 360,000 cubic feet. This company supplies that part of the metropolis whichlies west of Tottenham Court and Hampstead Roads and the north of Oxford Street, theEdgeware Road, the Regent’s Canal, Bayswater, Kensington, Hammersmith , Fulham, andChiswick .

The Grand Junction Water-works, established in the year 1810, arc situated at Chelsea,and at first derived their waters from the Thames , with which they filled three reservoirsat Paddington ; at present they are empowered to draw their supply from the same river,at a little above Kew Bridge, on the Surrey side. A steam-engine, of 500 horse-power,drives the water through a main, 30 inches in diameter, for a distance of 6 miles, toPaddington, where it is subjected to filtration. The total quantity supplied annuallywas 21,702,567 hogsheads to 7,700 houses; the daily consumption being estimated at2,800,000 gallons, or upwards of 450,000 feet. The highest elevation is 151 feet 9 inches,and the average quantity raised per day 3,744,213 gallons. This company supplies the dis-trict included within Oxford Street, Princes Street, St. James’s Park, Hyde Park, theEdgeware and Uxbridge Roads and the Regent's Canal. After making due allowancefor watering the streets and waste, the average consumption of each house, when Mr.Telford made his report, was estimated at 180 gallons per day, or 25 gaUons per day foreach person.

Southwark, and the south side of the Thames is supplied by the Lambeth, the SouthwarkCompanies, and the Yauxhall or South London .

The Lambeth Water-works are upon the Thames , between Westminster and Waterloobridges ; they have no reservoirs, the water being forced immediately from the river intothe mains, and thence distributed to about 16,000 tenants, who consume about 1,244,000gallons daily, or nearly 200,000 cube feet.

The Southwark Water-works are upon the banks of the Thames between Southwark andLondon bridges, and take their supply from the middle of the river opposite theirengines; 7000 tenants receive about 720,000 gallons of water, or 115,000 cubic feet,daily.

The Vauxhall or South London Water-works are in Kennington Lane, and have an engineon the river at the foot of Yauxhall Bridge ; they obtain the water from the Thames , andhave reservoirs for the service of their upper engine. They supply about 10,000 tenantswith about 1,000,000 gallons daily, or about 160,000 cubic feet.

Each of these establishments has two engines; the aggregate power of the six maybe estimated at about 235 horses ; the whole of the water furnished amounts to nearly3,000,000 gallons, or 485,000 cubic feet daily, which is distributed among 33,000 tenants.

East London Company , established in the year 1807, and situated at Old Ford, on the