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 channelway 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

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 " whether it be an upon which Matthews, in his Hydraulia, thus remarks : insurmountable 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."