'Appendix to the Weekly Return for the Week Ending 9th September' from The Registrar General's Weekly and Quarterly Returns of Births and Deaths in London for the Year 1853. London: Her Majesty's Stationery Office. LSHTM Library & Archives.
Although Snow and Farr were at odds over the communication of cholera, Snow borrowed from Farr's comprehensive statistics to aid his own investigation. In 1854 Farr published this appendix, listing 'all the deaths from cholera and diarrhoea that have been registered in the three weeks, extending from August the 19th to September 9th […] to assist in the investigation of the epidemic'. It was collaboration and access to information that led to the eventual validation of Snow's hypothesis.