Modern Spiritualism, published in two volumes in 1902, is Podmore's major work and is still cited by historians of the movement, which is unusual for a book written as a debunking. He traced the movement from the Fox sisters in New York State in 1848 through its spread across Britain and America, and worked through the major mediums case by case, setting out what had been claimed, what had been observed, and what ordinary explanation fitted. He was also the author of a substantial and unfriendly biography of Robert Owen and of a history of mesmerism, and the same method runs through all of them: establish the documentary record first, then ask what it will bear. His value to a reference work is that his scepticism was applied from inside, with full access to the society's files and to the investigators who had produced them, so his negative verdicts cannot be dismissed as the judgements of someone who had not looked. He drowned in a pond near Malvern in August 1910.
The inquest did not determine how he came to be in the water, and the circumstances have never been explained. What the book cannot do, and does not claim to do, is prove a negative. Showing that a given effect could have been produced by a given trick is not the same as showing that it was, and Podmore was more careful about that distinction than many who have cited him since.