Question: What is the name of the physician who studied the cause of the 1854 Broad Street cholera outbreak in London, England?

<P0-S0> The Ghost Map: The Story of London's Most Terrifying Epidemic – and How it Changed Science, Cities and the Modern World is a book by Steven Berlin Johnson in which he describes the most intense outbreak of cholera in Victorian London (See 1854 Broad Street cholera outbreak) The book incorporated the idea of gemeinschaft, dealing with the effects of an epidemic in a city of common values, language, and traditions. <P0-S1>  The two central protagonists are Dr. John Snow, who created a map of the cholera cases, and the Reverend Henry Whitehead, whose extensive knowledge of the local community helped determine the initial cause of the outbreak. <P0-S2>  Dr. John Snow was a revered anesthetist who carried out epidemiological work in Soho, London. <P0-S3>  Around the mid-1850s Snow figured out the source of cholera contamination to be the drinking water from the Broad Street pump. <SEP> <P1-S0> John Snow (15 March 1813 – 16 June 1858) was an English physician and a leader in the adoption of anaesthesia and medical hygiene. <P1-S1>  He is considered one of the fathers of modern epidemiology, in part because of his work in tracing the source of a cholera outbreak in Soho, London, in 1854. <P1-S2>  His findings inspired fundamental changes in the water and waste systems of London, which led to similar changes in other cities, and a significant improvement in general public health around the world. <SEP> <P2-S0> The Broad Street cholera outbreak (or Golden Square outbreak) was a severe outbreak of cholera that occurred in 1854 near Broad Street (now Broadwick Street) in the Soho district of London, England. <P2-S1>  This outbreak, which killed 616 people, is best known for the physician John Snow's study of its causes and his hypothesis that contaminated water, not air, was the source of cholera. <P2-S2>  This discovery came to influence public health and the construction of improved sanitation facilities beginning in the mid-19th century. <P2-S3>  Later, the term "focus of infection" would be used to describe sites, such as the Broad Street pump, in which conditions are good for transmission of an infection. <P2-S4>  John Snow's endeavor to find the cause of the transmission of cholera caused him to unknowingly create a double-blind experiment. <SEP> <P3-S0> Cholera Hospital was established on June 24, 1854, at Franklin Street in New York City. <P3-S1>  The institution was built to treat cholera patients who were denied admittance to City Hospital in Manhattan during an onset of the disease in the summer of 1854. <P3-S2>  The Mayor of New York, Jacob Westervelt, and the New York City Commissioners, took control of the building at 105 Franklin Street in anticipation of an eminent cholera epidemic. <P3-S3>  A few weeks afterward a second hospital for cholera sufferers was opened at a schoolhouse on Mott Street (Manhattan). <P3-S4>  A book published by a New York physician in 1835 shows that a hospital called the Duane-Street Cholera Hospital existed in New York as early as 1835, but the relationship between the Duane-Street hospital and the Cholera Hospital at Franklin Street is unclear.