With the terrible disease cholera at its heart, this is anything but a pleasant book to read – but that doesn’t stop it being horribly fascinating. Sandra Hempel has a gift for taking the reader into the heart of period medicine. Primarily a biography of John Snow, the man who cracked the mechanism for cholera’s spread, The Medical Detective also gives us a good deal of (sometimes graphic) description of the impact of cholera, an in-depth consideration of the UK political reaction to the cholera outbreaks, and a good feeling for the working environment that Snow would be familiar with. Although the US title, The Strange Case of the Broad Street Pump , is more effective in bringing out the medical Sherlock Holmes mystery aspect of the story, the Broad Street incident, of which more later, is very much the climax of the book, not cropping up until over half way through. Perhaps the most shattering aspect of Hempel’s story is the description of the Tooting child farm...