The Ghost Map: The Story of London’s Most Terrifying Epidemic—and How It Changed Science, Cities, and the Modern World

What does Johnson mean when he states that Snow’s and Whitehead’s friendship and collaboration was a “triumph of urbanism” (203)?

Johnson states approvingly of Snow and Whitehead that they were both “amateurs” in the work that they did together on cholera transmission. What do you think that he means by this, and how do you think that amateurism, in this context, might be a positive quality? How might it be preferable, in some ways, to being an expert?

The epilogue chapter in the book focuses on many of the threats that urban populations face today, such as global warming and chemical and nuclear warfare. What do you think that society has learned from John Snow and his response to the cholera epidemic in the modern-day attitude towards these threats?

What about the attitude of Victorian-era Londoners towards the cholera epidemic—and towards death and disasters in general—seems strange and old-fashioned to you? What about it seems familiar and relatable?

In Chapter 1, Johnson discusses coral reefs and their efficient natural recycling system. What do you think is the purpose of this digression? How does it relate to the topic of the book as a whole? 

The “miasma” theory of cholera transmission was obviously false and misguided, yet it was persuasive to many. What are some reasons why it remained so popular for so long?

Johnson speaks frequently of Snow’s “methodology.” What are some things that you think he means by this? How did this methodology distinguish him from other scientists, doctors, and public officials of his day?

What is modern about Henry Whitehead as a figure? What is old-fashioned about him? What important role did he play in his collaboration with Snow?