[BITList] Trickle-down effect

[John Feltham]

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Simpson,  James  (1799-1869), waterworks engineer, was born in London on 25 July 1799, the fourth son of Thomas Simpson, engineer of the Chelsea, and later Lambeth, water companies. Born in the engineer's residence at the waterworks on the north bank of the Thames, James Simpson learned engineering at his father's hand, worked under his father's direction, and inherited the position of chief engineer to both companies upon his father's death in 1823.

A few years after Simpson assumed his father's place the Chelsea company requested that the young engineer investigate the possibilities of filtering drinking water on a large scale. The company was responding to mounting complaints about the quality of their, and other companies', Thames-drawn water supply. Some feared, even in the absence of an established theory of waterborne disease, that the Chelsea water was 'destructive of health'  (J. Wright, The Dolphin, 1827, 61).

There were existing methods of small-scale filtration from which Simpson could work. First, there were well-known examples of Renaissance filter cisterns in which water passed through sand before collecting in a well. Then, there were small charcoal and sand filters for domestic use or for use at sea. Towards the end of the eighteenth century textile enterprises in Lancashire began filtering water in small beds, about 6 feet deep, lined with clay and layered with large stones, small stones, and gravelly sand. Water seeped from the sand to the stone layer, in the centre of which sat a perforated iron cylinder; the water trickling into this well was clear and ready to be used in dyeworks.

Paisley in Scotland enjoyed what some characterize as the first filtered municipal water supply. Distributed by carts bearing huge casks, however, it was provided on a limited, commercial basis. In 1804 a bleachworks owner, frustrated with the muddy, polluted local water sources available to the textile centre, constructed filter beds that worked on the same basic principle as the Lancashire filters. He took the added step of drawing off some of the purified water, casking it, and selling it door to door. Only a few years later Thomas Telford executed a filtration system, not particularly effective, for the Glasgow Water Works Company. There, water pumped from the Clyde passed down a series of small ponds and sand-filled cells before being piped to consumers. In mid-1827 Simpson toured the water filtration operations at Glasgow and at industrial sites near Manchester and elsewhere in Lancashire.

After undertaking over a year of experiments with prototype filter beds Simpson finally completed in January 1829 the filter beds for which he is renowned. Located at the site of the Chelsea works, the filter bed was 1 acre in area. Like some of the filters he had seen in the north, it was layered with a number of straining media. Water pumped into the bed first passed downward through a layer of fine sand, then coarse sand, then pebbles and shells, then fine gravel, then loose gravel. The water then entered perforated earthenware drainpipes that delivered it to a well from which it was finally pumped into the company's network of pipes. The filtered water was clear and free of odour. The occasional scraping of an inch or so from the top layer of sand kept the filter from clogging.

The water was mechanically strained, but the biological processes taking place in the uppermost strata truly accounted for the system's success. At the very surface of the sand a layer of bacteria, protozoa, and other organisms metabolized the organic matter before passing downward. Simpson did not understand the biological process going on, but knew that more than mere straining accounted for the clarity of the filtered water. 'Something more is evidently effected,' Simpson wrote, 'an appearance of fermentation being discernible when water is in contact with the sand'  (Baker, 111).

Working independently from Simpson, the Scottish engineer Robert Thom constructed a series of three smaller filter beds at Greenock over a year earlier that worked on the same principle as Simpson's large bed. Thom's featured the ability of cleaning the sand layer by reversing the flow of water and backwashing the filter media. The essence of Simpson's and Thom's scheme remains the basis of municipal water supply systems dependent on surface water throughout the world. Today waterworks often first chemically precipitate impurities from the water before it enters the separate sand filter bed. Chlorine and fluoride are regularly added after filtration.

In the ensuing decades Simpson maintained an extremely active career, his authority established by his early success and respect for him heightened by his renowned tact and courtesy. He provided a water supply for Windsor Castle and other royal palaces early in his career. He was at the forefront of a national movement for replacing inadequate and polluted town water supplies with purer sources drawn from long distances. Simpson completed a gravitation water scheme-a scheme for delivering water from an elevated source under pressure-for Bristol in 1851, piping water over 10 miles through great iron tubes. As the section of the Thames, near Hungerford Bridge, from where the Lambeth Water Company drew its water became heavily polluted by sewage, he was responsible for moving its operations to a site above Teddington Lock, at Seething Wells, Kingston upon Thames. Completed in March 1852, the Seething Wells waterworks used four 600 horse-power steam engines to pump ten million gallons from its filter beds to London consumers. He described his projects and methods in evidence to select committees on the London water supply in 1851 and 1852.

Simpson also designed or contributed to gravitation schemes at Aberdeen, Liverpool, Newport, and Stockport. He executed or was consulted on waterworks for Cambridge, Cardiff, Carlisle, Exeter, London, York, and elsewhere from the 1840s through the 1860s. Amsterdam and Copenhagen sought out his expertise and he was consulted on waterworks there in 1851 and 1856. He introduced innovations to steam pumping engines that, among other things, increased their efficiency of coal consumption. He trained his younger brother William (1809-1864) in engineering and aided him in the operation of a steam engine company in Pimlico, London.

Elected in 1825, Simpson was among the earliest members of the Institution of Civil Engineers, and was a vice-president from 1844 to 1853 and president in 1854 and 1855. With his wife, Sarah (b. 1799/1800), he had three sons, James, John, and Arthur, each of whom was connected with engineering or engine manufacturing. At least four of his grandsons were engineers involved with waterworks. He died at his home, Westfield Lodge, Portsmouth Road, Kingston upon Thames, Surrey, on 4 March 1869. A large gathering of members of the Institution of Civil Engineers, employees of his family's engine manufactory, associates from the waterworks companies with which he was connected, and other colleagues, along with his family, attended his funeral at Brompton cemetery.

Simpson heralded a new age of public health technology through his adaptation, refinement, and expansion of the sand filter in 1829. His accomplishment sustained the urbanization of Britain and was readily exported to colonial towns and throughout the world.

John Broich 

Sources  J. Simpson, memoir, PICE, 30 (1869-70), 457 + J. Simpson, presidential address, PICE, 13 (1853-4), 190, 204 + G. M. Binnie, Early Victorian water engineers (1981) + M. N. Baker, The quest for pure water (1948) + M. Melosi, The sanitary city (2000) + census returns, 1851, 1861 + 'Select committee on the metropolis water bill', Parl. papers, 15 (1851) + 'Select committee on the water supply of London and the Chelsea waterworks', Parl. papers, 12 (1852)
Likenesses  W. Boxall, oils, 1856, repro. in Baker, Pure water · S. Bellin, engraving (after W. Boxall, 1856), Inst. CE [see illus.]
Wealth at death  under £90,000: resworn administration, CGPLA Eng. & Wales