William Smith’s geological map of England is much better known than Farey’s, and was recently called, somewhat over-enthusiastically, "the map that changed the world". It is nevertheless a monumental cartographical achievement. It was issued in fifteen sections, and in our copy, the sections are bound as an atlas. Section 8 shows the area that includes Derbyshire. There is a formation that is colored bright blue, and looks a bit like a amoeba. This blue region contains the Derbyshire toadstone, and corresponds to Farey’s formations 8 and 9. In the bottom right corner of the blue area you can see the word "Matlock Bath." This is where Whitehurst made the section that we have on display (see exhibit item 42).