via West County Explorers Club: We've been reading Finding Your Way Without a Map or Compass by Harold Gatty, first published in 1958. It's a fascinating collection of navigation skills gleaned from the world of pre-Western and native explorers, in which one's own five senses (and memory) are the guides, instead of compasses, maps, or GPS.
In the book, Gatty furthers the theory that early Polynesians first found their way across the Pacific by following the routes of migratory birds. Once the islands were known, they followed the stars. For example, if you hold a forked stick at arm's length, and position the North Star in the crook of the fork, then note it's height by marking the horizon along its length, you will travel along a constant latitude. If the North Star rises against the horizon, you're heading north. If it falls, you're heading south.
It's quite an interesting read. Hat's off to my girlfriend, Natalie, for finding this one.