Chapter 1: Imaginary Lines Summary and Analysis

Chapter 1 begins by explaining the history of the longitude problems. It turns out that assigning latitude - or the east to west running lines on maps - is not terribly complicated. Ptolemy was one of the first latitude mapmakers. But the author notes that longitude is not fixed by the laws of nature, as latitude is. Instead it must be stipulated in a form that is practical for the use of sailors. Longitude can typically be calculated as a function of speed and distance. But at sea, there are no landmarks to distinguish these two variables. A ship may travel far and fast or slowly and only a short-distance. Without landmarks it is difficult to tell. And if a ship is thrown off course perhaps during a storm, then the captain cannot find the ship's location without...