the Old Ford Reservoir in East London. Farr's work was then considered conclusive. Later life In 1858, he performed a study on the correlation of health and marriage condition, and found that health decreases from the married to the unmarried to the widowed. In the period 1857–9 the Office ordered a difference engine, a model designed by Swedish followers of Charles Babbage. The intended application was the "British Life Table". Farr served as a commissioner in the 1871 census, retiring from the General Register Office in 1879 after he was not given the post of Registrar General, the position going to Sir Brydges Henniker. The same year, Farr received as honours a Companionship of the Bath and the Gold Medal of the British Medical Association for his work in the field of biostatistics. In his last years, Farr's approach had become obsolescent. Bacteriology had changed the face of the medical issues, and statistics became an increasingly mathematic tool. Medical reformers, too, changed approach, expecting less from legislation and central government. Farr died aged 75 at his home in Maida Vale, London, and was buried at Bromley Common. Works In 1837 Farr wrote the chapter "Vital Statistics" for John Ramsey McCulloch's Statistical Account of the British Empire. In January 1837 he established the British Annals of Medicine, Pharmacy, Vital Statistics, and General Science, discontinued in August of that year. He revised a book of James Fernandez Clarke on tuberculosis. Farr exploited his GRO post compiling abstracts in a way that went beyond the original job description. In so doing he applied the techniques of the English actuary Benjamin Gompertz (the Gompertz curve), and the closely allied statistical "law of mortality" of his fellow actuary Thomas Rowe Edmonds. Farr, by relying on the existing mathematical model of mortality, could use data sampling to cut back the required computation. From the GRO data he constructed a series of national life tables. The theory of zymotic disease was Farr's contribution to the debate on aetiology. He identified urbanisation and population density as public health issues. In terms of nosology he classed epidemic, endemic and contagious diseases as "zymotic", seen as diseases of filth and overcrowding. A selection of his statistical writings was published in 1885, edited by Noël Humphreys. In drama In "The Sewer King", an episode in the 2003 British television documentary series Seven Wonders of the Industrial World, Farr was played by