Hills of Silver Ruins (1/17)

In this chapter, we learn why GPS is such a big deal. As Dava Sobel explains in Longitude, locating a ship's position at sea was literally a matter of life and death. Finally in the early 18th century, the British Parliament offered the equivalent of four million dollars for a practical solution. Even in the first half of the 20th century, it was common practice for aviators flying over land to follow the train tracks.

The magnetic compass was adopted for navigation by the Song Dynasty during the 11th century.

Hien (飛燕) is Risai's kijuu.