In the beginning, there was Dava Sobel and Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time (1998). Others followed, in a veritable flood which D. P. Miller recently dubbed the ‘Sobel Effect’. Academic historians of science have been concerned by this flood, partly because people other than them are (presumably) making money out of ‘their’ subject, but also because of the ways it might affect the public perception of the history of science. Like the scientists they study, historians fear that popularizers will distort in the process of simplifying. But, knowing how difficult it has been for scientists to control the popularization of their subject, historians may not expect a great deal more success.