Graunt's Observations on the Bills of Mortality

When a Londoner died, the parish searchers, elderly women sworn to the office, went to view the body and decide what the person had died of. They reported to the parish clerk, who handed in a count of burials and christenings every Tuesday night. The Worshipful Company of Parish Clerks printed these weekly Bills of Mortality on and off until 1595 and without a break from 1603.

John Graunt, a London haberdasher and councilman, treated the bills as data. His Natural and Political Observations, signed from Birchen Lane in January 1662, gathered them into tables. Of 229,250 deaths over twenty years, he reckoned that about a third were young children, and that of every 100 live conceptions about 36 died before the age of six. He put London's population at about 384,000, with 14 males for every 13 females, while admitting the estimate was rough.

The bills also showed diseases rising and falling. Rickets, which Graunt called new in both name and thing, went from 14 deaths in 1634 to more than 500 in 1660. Fewer than one death in 1,500 was put down to lunacy, and he suspected that many deaths from the French pox were recorded as consumption. He also drew up a table of how many of 100 conceptions would still be alive at each decade of life: 64 at six, 40 at 16, 25 at 26 and 16 at 36.

Graunt addressed the book to the president and fellows of the Royal Society, then meeting at Gresham College. The Science Museum credits him and his friend William Petty with early statistical and census methods such as life tables. The raw material had limits he could not repair. Because Church of England parishes kept the bills, they left out members of other churches and people who went to no church at all.