"Longitude" by Dava Sobel. Sailors knew for a while how to get your latitude (by using the position of the north star) but didn't have a way of getting their l

"Longitude" by Dava Sobel. Sailors knew for a while how to get your latitude (by using the position of the north star) but didn't have a way of getting their longitude pre-18th century. This was a serious problem in navigation and this is the story of how a solution came about.