In the essay On Mode of Communication Cholera what is primary technique that author John Snow uses to support his claim cholera spreads from person person?

The primary technique John Snow uses to support his claim that cholera spreads from person to person in his essay "On the Mode of Communication of Cholera" is the meticulous collection and analysis of epidemiological data.

He uses the following methods:

* Mapping and Geographic Analysis: Snow meticulously mapped the locations of cholera cases in London, particularly focusing on the Broad Street pump area. This helped him identify the source of the outbreak and demonstrate the clustering of cases around the infected water pump.

* Statistical Analysis: Snow collected data on the number of deaths, the demographics of those affected, and their water sources. He compared these statistics to identify patterns and correlations that supported his hypothesis of person-to-person transmission.

* Observation and Interviews: He went door-to-door interviewing residents, collecting information about their symptoms, water consumption habits, and potential exposures. This allowed him to gather qualitative evidence further supporting his claim.

* Controlled Experiment: He famously removed the handle from the Broad Street pump, essentially conducting a controlled experiment. This action dramatically reduced the spread of the disease, proving the pump was a primary source of contamination and supporting his theory of person-to-person transmission.

By combining these techniques, Snow built a strong case for his claim, effectively challenging the prevailing miasma theory of disease and laying the groundwork for the germ theory of disease. His work remains a landmark example of the power of epidemiology in identifying and controlling infectious diseases.