Echoes in the Valley Book

Great book on how the Mason-Dixon line was actually surveyed, which is actually a pretty exciting story. Unfortunately, Danson has to explain the technical details behind the achievement, which many other readers found difficult to follow. (If you're not good at math, especially geometry, I can see that happening. The calculations and explanations aren't particularly daunting within the text because the appendices provide most of the detail, but just hearing about triangulation and taking a tangent is enough to scare off some readers.) So, if you're looking for more of a social history or an adventure, this isn't the book for you. (Frequent mention of the grueling cold nights lying on the ground just to calibrate the astronomical equipment reminds you just how hard the life of a scientist used to be.) But if you're curious about how Mason and Dixon determined the Pennsylvania-Maryland border (the actual nitty-gritty of surveying) and measured 1 degree of latitude with a high confidence interval for their era, than this is the book for you.