William Farr (1807-1883)

William Farr.

William Farr.

Credits:Wellcome Library, London.

William Farr was a leading British epidemiologist who was a pioneer in the field of medical statistics. A qualified doctor, he was able to develop his interest in the generation and use of medical statistics following his appointment in 1838 to the General Register Office (GRO) - the government department responsible for recording births, deaths and marriages. Here his most important contribution to public health was in setting up a system that routinely recorded the cause of death. Such detailed statistics provided the raw data which allowed a far more detailed analysis of death within the general population. For example, the mortality rates of different professions or of those living in different locations could be compared.

Like most of his medical contemporaries, he subscribed to the miasma theory of disease. As such he took particular interest in environmental conditions. For example, he suggested that in low-lying ground along the banks of the River Thames the concentrations of deadly miasmas would be greater than on higher land situated further away from the river. This seemed to be confirmed in his report on the 1849 cholera epidemic, published in 1852, where Farr’s statistical calculations suggested a link between deaths and land elevation. This was promoted as further evidence of miasma theory.

Although they disagreed over the cause of cholera transmission, John Snow used the detailed statistics produced by Farr when developing his own alternative theory. However, William Farr remained unconvinced by Snow’s work, and when Farr’s committee reported on the next cholera outbreak - centred on the Broad Street pump - they made a point of dismissing Snow’s proposal of a waterborne mode of transmission.

Farr was finally converted to Snow’s theory in the wake of the final London cholera epidemic of 1866. Snow’s report showed a clear linkage between victims of the epidemic and one particular water source, which in his opinion suggested that water, rather than air, was the likely cause of disease transmission.